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Pharmacology Flashcards
Medical Calculators
Universal / Vital Signs
BMIBody Mass Index
NEWS2Early Warning Score
GCSGlasgow Coma Scale
IBW / ABWIdeal Body Weight
BSABody Surface Area
MAPMean Arterial Pressure
Cardiology
CHA₂DS₂-VAScAF Stroke Risk
JonesRheumatic Fever
HAS-BLEDBleeding Risk
ORBITBleeding Risk (NICE)
GRACEACS Mortality
QTcCorrected QT
HEARTChest Pain MACE
QRISK®310-yr CVD Risk
Respiratory
PaduaVTE Risk
GenevaPE Probability
CURB-65CAP Severity
Wells DVTDVT Probability
Wells PEPE Probability
sPESIPE Severity
PERCPE Rule-out
Light'sPleural Exudate
Sepsis / Acute / Surgical
ParklandBurns Fluids
Ottawa RulesAnkle/Knee X-ray
qSOFASepsis Screening
SOFAOrgan Failure
AlvaradoAppendicitis
Glasgow-BlatchfordUpper GI Bleed
RockallGI Bleed Risk
Renal / Chemistry
Corrected NaHyperglycaemia
eGFRCKD-EPI 2021
Cockcroft-GaultCrCl Estimation
FENaFractional Excretion Na
Anion GapMetabolic Acidosis
Corrected Ca²⁺Albumin-adjusted
OsmolalitySerum Osmolality
Free Water DeficitHypernatraemia
A-a GradientAlveolar-arterial O₂
Liver / GI
Child-PughCirrhosis Severity
MELDLiver Disease Mortality
Maddrey DFAlcoholic Hepatitis
Glasgow-ImriePancreatitis Severity
SAAGAscites Gradient
Endocrine / Metabolic
Maintenance FluidsHolliday-Segar / Parkland
Obstetrics
Bishop ScoreCervical Ripening
EDD / GAGestational Age
APGARNewborn Score
Neuro / Elderly
CT HeadHead Injury Imaging
PHQ-9Depression
AMT-10Abbreviated Mental Test
ROSIERStroke Recognition
CIWA-ArAlcohol Withdrawal
NIHSSStroke Severity
4ATDelirium Screen
ABCD²TIA Stroke Risk
Frailty (CFS)Rockwood Scale
AUDIT-CAlcohol Screen
Infection / ID
FeverPAINSore Throat
Centor / McIsaacStrep Throat
Duke CriteriaEndocarditis
Parkland Formula — Burns Fluid Resuscitation
4 mL × weight (kg) × %TBSA over 24 h; half in the first 8 hours (from the time of the burn).
📖 Notes
💡 Why we use it
- Estimates the crystalloid needed in the first 24 h of a significant burn (≥15% TBSA in adults, ≥10% in children) to prevent burn shock and acute kidney injury.
- Under-resuscitation causes shock and AKI; over-resuscitation causes oedema, compartment syndrome and pulmonary oedema — so it is a starting estimate, then titrate.
📊 What the result means
- Total = 4 mL × kg × %TBSA of Hartmann’s over 24 h.
- Half in the first 8 hours (from the time of injury, not arrival), the rest over the next 16 h.
- Titrate to urine output 0.5 mL/kg/h (adult) or 1 mL/kg/h (child).
Estimate %TBSA with the Wallace rule of 9s / Lund–Browder chart and EXCLUDE simple erythema. Children also need maintenance fluids (with glucose) on top. Refer major burns to a specialist unit.
🩺 Case Practice 5 scenarios · calculate & decide
Work through each patient: why you’re resuscitating, the volume itself, what it means, and what you’d do next.
Ottawa Ankle, Foot & Knee Rules
Decide who needs an X-ray after ankle, foot or knee injury.
Ankle / foot X-ray — indicated if ANY:
Knee X-ray — indicated if ANY:
📝 Notes & interpretation▾
💡 Why we use it
- Highly sensitive (≈100%) rules to safely EXCLUDE fracture and avoid unnecessary X-rays after ankle, foot or knee injury.
- Reduce imaging, radiation and waiting times without missing clinically important fractures.
📊 What the result means
- Any criterion positive → X-ray the relevant joint.
- All negative → no X-ray needed (fracture very unlikely).
Apply within 10 days of injury. Less reliable if intoxicated, uncooperative, distracting injuries, reduced limb sensation, or in young children.
🧩 Case practice5 scenarios
CT Head Rule (NICE Head Injury)
Who needs a CT head after injury, and how urgently.
CT within 1 hour if ANY:
CT within 8 hours if ANY (with LOC or amnesia):
📝 Notes & interpretation▾
💡 Why we use it
- Identifies the head-injured patients who need CT to detect clinically important brain injury, and stratifies urgency (1 h vs 8 h).
- Avoids scanning everyone while catching intracranial bleeds early — including in anticoagulated patients.
📊 What the result means
- Any 1-hour criterion → CT within 1 hour.
- Otherwise any 8-hour criterion → CT within 8 hours.
- None → observe or discharge with written head-injury advice.
Anticoagulation with any head injury warrants CT within 8 hours even without other features. Safety-net all discharges.
🧩 Case practice5 scenarios
Corrected Sodium (Hyperglycaemia)
Corrects measured sodium for the dilutional effect of a high glucose.
📝 Notes & interpretation▾
💡 Why we use it
- Hyperglycaemia draws water into the vascular space and dilutes sodium, causing a spurious (dilutional) hyponatraemia.
- Correcting reveals the true sodium so you don’t over-treat a "low" sodium that will normalise as glucose falls (e.g. in DKA/HHS).
📊 What the result means
- Corrected Na = measured Na + 2.4 × (glucose − 5.5)/5.5 (Hillier; the older Katz factor is 1.6).
- Interpret the corrected value, then recheck as glucose is treated.
Related acid–base rule — Winters’ formula: expected pCO₂ = 1.5 × HCO₃⁻ + 8 (±2), used to check the respiratory compensation in a metabolic acidosis (e.g. DKA) is appropriate.
🧩 Case practice5 scenarios
Padua Prediction Score — VTE Risk
VTE risk in hospitalised MEDICAL patients. ≥4 = high risk → thromboprophylaxis.
Risk factors
📝 Notes & interpretation▾
💡 Why we use it
- Standardises the VTE risk assessment every hospitalised medical patient should get, to decide on pharmacological thromboprophylaxis.
- Balances a real VTE risk against bleeding risk — prophylaxis prevents avoidable, sometimes fatal, hospital-acquired PE.
📊 What the result means
- ≥4 → high VTE risk: offer pharmacological thromboprophylaxis (e.g. LMWH) unless contraindicated.
- <4 → low risk: generally mechanical measures / early mobilisation.
Always weigh against bleeding risk and check for contraindications; this applies to medical inpatients (surgical patients use surgical VTE tools).
🧩 Case practice5 scenarios
PHQ-9 — Depression Severity
Over the last 2 weeks, how often bothered by each problem? (0–3 each, total 0–27.)
📝 Notes & interpretation▾
💡 Why we use it
- A validated, self-report tool to screen for and grade the severity of depression, and to track response to treatment.
- Item 9 specifically screens for thoughts of self-harm — always review and act on a positive response.
📊 What the result means
0–4 None/minimal
5–9 Mild
10–14 Moderate
15–19 Moderately severe
20–27 Severe
Pair with GAD-7 (anxiety) in practice. A raised score supports — but does not replace — a clinical diagnosis; always assess risk (item 9) and function.
🧩 Case practice5 scenarios
Revised Geneva Score — PE
Pre-test probability of PE (objective — no gestalt item, unlike Wells).
Criteria
📝 Notes & interpretation▾
💡 Why we use it
- An entirely objective PE pre-test probability score (no subjective "PE is most likely" item), useful when clinical gestalt is uncertain or for standardised pathways.
- Directs the same logic as Wells: low/unlikely → D-dimer; high/likely → imaging (CTPA).
📊 What the result means
0–3 Low probability
4–10 Intermediate
≥11 High probability
A two-level version splits at unlikely (≤5) vs likely (≥6). Related severity/prognosis tools for confirmed PE: PESI / sPESI. (For pancreatitis prognosis, the Glasgow–Imrie score is elsewhere in this list; Ranson is the US equivalent.)
🧩 Case practice5 scenarios
Jones Criteria — Acute Rheumatic Fever
Evidence of preceding group A strep PLUS 2 major, or 1 major + 2 minor (or 3 minor if recurrent).
Preceding infection
Major criteria
Minor criteria
📖 Notes
💡 Why we use it
- Standardises the diagnosis of acute rheumatic fever — the cause of rheumatic heart disease, still a leading cause of acquired heart disease in children worldwide.
- No single test is diagnostic: it combines clinical features with evidence of a preceding group A streptococcal infection.
- Making the diagnosis triggers secondary prophylaxis (long-term penicillin) to prevent recurrences and cumulative valve damage.
📊 What the result means
- Diagnosis = evidence of preceding strep PLUS 2 major, or 1 major + 2 minor (initial); a recurrence may also be diagnosed with 3 minor.
- Major (JONES): Joints (arthritis), ♥ carditis, Nodules (subcutaneous), Erythema marginatum, Sydenham chorea.
- Minor: fever, arthralgia, raised ESR/CRP, prolonged PR interval.
- 2015 revision: risk-stratified thresholds (lower cut-offs in moderate/high-risk populations) and subclinical carditis on echo counts as a major criterion.
Exceptions: Sydenham chorea and indolent carditis can each diagnose ARF on their own, even without other criteria or documented strep. A joint finding counts once (arthritis OR arthralgia), and prolonged PR is not a minor criterion when carditis is already a major.
🩺 Case Practice 5 scenarios · assess & decide
Work through each patient: why you’re applying the criteria, count them, decide if ARF is diagnosed, and what to do next.
QRISK®3 — 10-year Cardiovascular Risk
Estimates 10-year risk of heart attack or stroke (QRISK3-2017). For ages 25–84 without prior CVD.
Clinical history
📖 Notes
💡 Why we use it
- Estimates 10-year risk of heart attack or stroke to guide primary prevention — the UK/NICE standard.
- Uses far more than cholesterol: age, sex, ethnicity, deprivation, BMI, blood pressure (and its variability), smoking, diabetes and a range of comorbidities.
- Identifies who benefits from a statin and supports shared decision-making.
📊 What the result means
<10% — Lifestyle advice; reassess periodically.
≥10% — Offer atorvastatin 20 mg for primary prevention (NICE).
≥20% — High risk — atorvastatin 20 mg is already high-intensity; focus on aggressive risk-factor modification.
For primary prevention only — not for established CVD, type 1 diabetes, CKD or familial hypercholesterolaemia, who are treated regardless of score. Validated for ages 25–84; confirm against the official qrisk.org before acting.
QRISK®3 licence & disclaimer (ClinRisk Ltd, LGPL v3)
The initial implementation, to be found at http://svn.clinrisk.co.uk/opensource/qrisk2, faithfully implements QRISK3-2017. ClinRisk Ltd. have released this code under the GNU Lesser General Public License to enable others to implement the algorithm faithfully. However, the nature of the GNU Lesser General Public License is such that we cannot prevent, for example, someone accidentally altering the coefficients, getting the inputs wrong, or just poor programming. ClinRisk Ltd. stress, therefore, that it is the responsibility of the end user to check that the source that they receive produces the same results as the original code found at https://qrisk.org. Inaccurate implementations of risk scores can lead to wrong patients being given the wrong treatment.
🩺 Case Practice 5 scenarios · calculate & decide
Work through each patient: why you’re calculating, the value itself, what it means, and what you’d do next.
QTc — Corrected QT Interval
Rate-corrects the measured QT. Bazett (primary) with Fridericia shown.
📖 Notes
💡 Why we use it
- Corrects the measured QT interval for heart rate so it can be compared across patients and over time.
- A prolonged QTc predisposes to torsades de pointes and sudden cardiac death — check it before and during QT-prolonging drugs (many antipsychotics, antiemetics, macrolides, methadone).
- Bazett is the classic correction; Fridericia is more reliable at extremes of heart rate.
📊 What the result means
Normal — ≤450 ms (men) / ≤470 ms (women).
Prolonged — >450 (men) / >470 (women) — review/stop offending drugs, correct K⁺/Mg²⁺/Ca²⁺.
>500 ms — Markedly prolonged — high torsades risk; stop QT-prolonging drugs, monitor.
Also flag a short QTc (<350 ms). Bazett over-corrects at fast heart rates and under-corrects at slow ones — cross-check with Fridericia when the rate is extreme.
🩺 Case Practice 5 scenarios · calculate & decide
Work through each patient: why you’re calculating, the value itself, what it means, and what you’d do next.
HEART Score — Chest Pain
MACE risk in undifferentiated chest pain (ED).
📖 Notes
💡 Why we use it
- Risk-stratifies undifferentiated chest pain in the emergency department for major adverse cardiac events (MACE) at 6 weeks.
- Helps decide safe discharge vs admission — outperforms gestalt (and TIMI/GRACE) for this specific ED triage question.
- Combines History, ECG, Age, Risk factors and Troponin, each scored 0–2.
📊 What the result means
0–3 — Low risk (~1–2% MACE) — consider discharge with safety-netting.
4–6 — Moderate (~12–17%) — admit/observe with serial troponin.
7–10 — High (~50–65%) — early invasive strategy.
Designed for undifferentiated ED chest pain, not confirmed ACS (use GRACE there). A high-sensitivity troponin pathway can refine the troponin component.
🩺 Case Practice 5 scenarios · calculate & decide
Work through each patient: why you’re calculating, the value itself, what it means, and what you’d do next.
Glasgow-Imrie — Pancreatitis
Predicts severe acute pancreatitis (assess within 48 h). PANCREAS.
Criteria
📝 Notes & interpretation▾
💡 Why we use it
- Predicts severe acute pancreatitis (and the need for HDU/ITU) within 48 hours of admission.
- Early identification of severe disease drives escalation, aggressive fluids and monitoring for complications.
- Eight criteria (PANCREAS), scored within the first 48 h.
📊 What the result means
0–2 — Predicted mild — ward-level supportive care.
≥3 — Predicted severe — consider HDU/ITU, closer monitoring, watch for necrosis/organ failure.
Assessed within 48 h (not on admission). Severity is also judged by CRP (>150 at 48 h), the revised Atlanta criteria and organ failure — the score is one input, not the whole picture.
🧩 Case practice5 scenarios
NIHSS — Stroke Severity
15-item stroke scale (0–42). Guides thrombolysis/thrombectomy.
📝 Notes & interpretation▾
💡 Why we use it
- Standardised 15-item scale that quantifies the neurological deficit from an acute stroke.
- Guides treatment decisions (thrombolysis/thrombectomy), predicts outcome and tracks change over time.
- A common language for stroke severity across the team and between hospitals.
📊 What the result means
0–4 — No / minor stroke.
5–15 — Moderate stroke.
16–42 — Moderate–severe (16–20) to severe (21–42) stroke.
Higher scores favour intervention but carry higher haemorrhage risk — decisions weigh score against time, imaging and comorbidity. It under-weights posterior-circulation strokes (a small NIHSS can still be disabling). Score what you observe.
🧩 Case practice5 scenarios
4AT — Delirium Screen
Rapid bedside delirium/cognitive screen (NICE-endorsed).
📝 Notes & interpretation▾
💡 Why we use it
- Rapid (<2 min) bedside tool to detect delirium and cognitive impairment — no special training needed.
- Endorsed for routine delirium screening in acute and older-adult settings (NICE/SIGN).
- Assesses alertness, AMT-4 orientation, attention (months backwards) and acute change/fluctuation.
📊 What the result means
0 — Delirium or cognitive impairment unlikely.
1–3 — Possible cognitive impairment (not acute) → further assessment.
≥4 — Possible delirium ± cognitive impairment → find the cause.
A positive 4AT is a prompt to find and treat the cause (infection, drugs, metabolic, urinary retention/constipation), not a diagnosis in itself. It works even in drowsy or agitated patients — and delirium fluctuates, so reassess.
🧩 Case practice5 scenarios
FeverPAIN — Sore Throat
Guides antibiotic decisions for acute sore throat (NICE).
Criteria
📝 Notes & interpretation▾
💡 Why we use it
- Estimates the likelihood that a sore throat is streptococcal, to target antibiotics (NICE).
- Reduces unnecessary prescribing for self-limiting viral sore throats.
- Points for Fever (24 h), Purulence, Attend rapidly (≤3 days), Inflamed tonsils, No cough/coryza.
📊 What the result means
0–1 — ~13–18% strep — no antibiotic; self-care.
2–3 — ~34–40% — no or delayed (back-up) antibiotic.
4–5 — ~62–65% — immediate or delayed antibiotic by severity.
First-line is phenoxymethylpenicillin (clarithromycin/erythromycin if penicillin-allergic). FeverPAIN or Centor may be used — FeverPAIN is NICE-preferred. Beware red flags: stridor, drooling, trismus or unilateral swelling → quinsy/epiglottitis.
🧩 Case practice5 scenarios
Centor / McIsaac — Strep Throat
Likelihood of group A streptococcal pharyngitis (age-adjusted).
Criteria
📝 Notes & interpretation▾
💡 Why we use it
- Estimates the probability of group A streptococcal pharyngitis to guide testing/antibiotics.
- The McIsaac modification adds an age adjustment (children higher risk, older adults lower).
- Points for tonsillar exudate, tender anterior cervical nodes, fever >38 °C, absence of cough.
📊 What the result means
≤1 — Low (~5–10%) — no antibiotic or testing.
2–3 — Intermediate (~11–35%) — consider rapid antigen test / delayed antibiotic.
≥4 — High (~50%) — consider antibiotic (or test first).
Interchangeable with FeverPAIN for the same decision (NICE prefers FeverPAIN). It predicts streptococcal likelihood, not the need to treat — most sore throats are viral and self-limiting whatever the score. Note: NICE NG84 advises against routinely offering a throat swab or rapid antigen test in primary care — the score itself guides the antibiotic decision.
🧩 Case practice5 scenarios
ABCD² — TIA Stroke Risk
Early stroke risk after TIA.
Criteria
📝 Notes & interpretation▾
💡 Why we use it
- Estimates the short-term (2- and 7-day) risk of stroke after a TIA.
- Historically used to triage who needed same-day specialist review.
- Points for Age ≥60, BP ≥140/90, Clinical features (weakness/speech), Duration and Diabetes.
📊 What the result means
0–3 — Low 2-day stroke risk (~1%).
4–5 — Moderate (~4%).
6–7 — High (~8%).
NICE no longer uses ABCD² to decide urgency — ALL suspected TIAs should be seen by a specialist within 24 hours and started on aspirin (unless contraindicated). The score illustrates risk; it is not a gatekeeper.
🧩 Case practice5 scenarios
AUDIT-C — Alcohol Screen
3-item alcohol-use screen.
📝 Notes & interpretation▾
💡 Why we use it
- Three-question screen (from the full 10-item AUDIT) for hazardous or harmful drinking.
- Quick case-finding in primary care, EDs and clinics to trigger brief intervention.
- Scores frequency, typical quantity and frequency of heavy-drinking episodes.
📊 What the result means
0–4 (men) / 0–3 (women) — Lower risk.
≥5 (men) / ≥4 (women) — Increasing-risk drinking → brief advice.
≥8 — Higher-risk / possible dependence → fuller assessment (full AUDIT).
A positive screen warrants a brief intervention, not a label. If dependence is likely, do not advise abrupt cessation without support — assess withdrawal risk and cover with thiamine ± benzodiazepines as needed. UK CMO low-risk guidance is ≤14 units/week for both men and women, spread over 3 or more days.
🧩 Case practice5 scenarios
Light's Criteria — Pleural Effusion
Classifies a pleural effusion as exudate or transudate.
📖 Notes
💡 Why we use it
- Classifies a pleural effusion as exudate or transudate — the first fork in the diagnostic pathway.
- Decides whether to hunt for a local pleural cause (exudate) or a systemic one (transudate).
- Very sensitive for picking up exudates.
📊 What the result means
- An effusion is an exudate if ANY one holds: pleural/serum protein >0.5; pleural/serum LDH >0.6; pleural LDH > ⅔ of the upper limit of normal serum LDH.
- If none are met it is a transudate.
- Exudate → infection (empyema/parapneumonic), malignancy, PE, TB.
- Transudate → heart failure, cirrhosis, hypoalbuminaemia, nephrotic syndrome.
On diuretics (e.g. heart failure), Light’s can mislabel a transudate as an exudate — if it looks clinically like a transudate, check the serum–pleural albumin gradient (>12 g/L favours a transudate).
🩺 Case Practice 5 scenarios · calculate & decide
Work through each patient: why you’re classifying the fluid, calculate the ratio, decide exudate vs transudate, and what you’d do next.
SAAG — Serum-Ascites Albumin Gradient
Serum albumin − ascitic albumin. Distinguishes portal hypertension.
📝 Notes & interpretation▾
💡 Why we use it
- Determines whether ascites is due to portal hypertension or not — the key branch point in the ascites work-up.
- More reliable for ascites than the old exudate/transudate split.
- Serum albumin minus ascitic-fluid albumin (both g/L).
📊 What the result means
≥11 g/L (high gradient) — Portal hypertension — cirrhosis, heart failure, Budd-Chiari, portal vein thrombosis.
<11 g/L (low gradient) — Non-portal — malignancy, TB peritonitis, pancreatitis, nephrotic syndrome.
A gradient ≥11 g/L (1.1 g/dL) predicts portal hypertension with ~97% accuracy. Always also send fluid for cell count (neutrophils ≥250/mm³ = spontaneous bacterial peritonitis), protein, culture and cytology.
🧩 Case practice5 scenarios
APGAR — Newborn Assessment
Scored at 1 and 5 minutes (0–10).
📝 Notes & interpretation▾
💡 Why we use it
- Rapid standardised assessment of a newborn’s condition at 1 and 5 minutes, to guide support and communicate status.
- The 1-minute score reflects the intra-partum period; the 5-minute score reflects response to resuscitation and correlates better with outcome.
- Scores Appearance, Pulse, Grimace, Activity and Respiration (0–2 each).
📊 What the result means
7–10 — Reassuring — routine care.
4–6 — Moderately depressed — stimulate; may need airway/oxygen support.
0–3 — Severely depressed — active resuscitation required.
Not a measure of asphyxia or long-term outcome, and it does not decide when to START resuscitation (that begins immediately if needed, before the 1-minute score). If <7, repeat every 5 minutes up to 20 minutes.
🧩 Case practice5 scenarios
Clinical Frailty Scale
Rockwood 9-point frailty scale — informs escalation decisions.
📝 Notes & interpretation▾
💡 Why we use it
- A 9-point judgement-based scale summarising overall fitness/frailty, from "very fit" to "terminally ill."
- Informs escalation and treatment ceilings (e.g. ICU admission), prognosis and comprehensive geriatric assessment.
- Widely used in acute medicine, surgery and critical care.
📊 What the result means
1–3 — Fit / managing well.
4–6 — Vulnerable to moderately frail.
7–9 — Severe / very severe frailty / terminally ill.
Score the patient’s BASELINE (2 weeks before the acute illness), not their current acute state. Validated for ages ≥65 and not designed for stable lifelong disability. It complements — never replaces — holistic assessment and the patient’s wishes.
🧩 Case practice5 scenarios
PERC — PE Rule-out
Valid only when clinical gestalt is low risk (<15%). Any positive = not ruled out.
Criteria
📖 Notes
💡 Why we use it
- Lets you rule OUT pulmonary embolism with no testing at all (not even a D-dimer) in patients already judged low-risk by clinical gestalt.
- Cuts unnecessary D-dimers and CTPAs — and their false positives, radiation and contrast — in the lowest-risk group.
- Eight criteria; all must be absent to be PERC-negative.
📊 What the result means
0 criteria (PERC-negative) — PE effectively excluded (<2%) in a low-probability patient — no further testing.
≥1 criterion (PERC-positive) — Cannot rule out PE → proceed to D-dimer (± CTPA).
Valid ONLY when your clinical gestalt is already low risk (<15%). It does not apply to moderate/high pre-test probability — there you go straight to D-dimer or imaging. PERC is a US-derived rule and is not part of NICE NG158 (which uses the two-level Wells score plus D-dimer) — treat it as an adjunct to clinical gestalt, not a UK-guideline pathway.
🩺 Case Practice 5 scenarios · assess & decide
Work through each patient: why you’re applying PERC, count the criteria, decide what it means, and what you’d do next.
Duke Criteria — Endocarditis
Modified Duke criteria for infective endocarditis.
Major criteria
Minor criteria
📝 Notes & interpretation▾
💡 Why we use it
- The diagnostic framework for infective endocarditis, combining microbiological, echo and clinical findings.
- Classifies cases as definite, possible or rejected to guide investigation and treatment.
- Anchored on two pillars: positive blood cultures (typical organisms) and endocardial involvement on echo.
📊 What the result means
Definite IE — 2 major, or 1 major + 3 minor, or 5 minor → treat (prolonged IV antibiotics ± surgery).
Possible IE — 1 major + 1 minor, or 3 minor → keep investigating (repeat cultures, TOE).
Rejected — Criteria not met / firm alternative / resolves within ≤4 days of antibiotics.
Take THREE sets of blood cultures from different sites before antibiotics. TOE is far more sensitive than TTE (especially prosthetic valves / small vegetations) — a negative TTE does not exclude IE. Culture-negative endocarditis (prior antibiotics, Coxiella, Bartonella) needs special work-up.
🧩 Case practice5 scenarios
BMI — Body Mass Index
Weight (kg) ÷ Height (m)². WHO classification.
📖 Notes
💡 Why we use it
- Screens weight-related health risk from just height and weight — quick, cheap and non-invasive.
- Stratifies risk of type 2 diabetes, cardiovascular disease and obstructive sleep apnoea, and flags under-nutrition.
- Standardised, so you can track change over time and compare across populations.
📊 What the result means
<18.5 — Underweight
18.5–24.9 — Healthy weight
25–29.9 — Overweight
30–34.9 — Obese class I
35–39.9 — Obese class II
≥40 — Obese class III
Doesn’t distinguish muscle from fat — misleading in athletes, pregnancy and the elderly. Select the high-risk ethnicity option to apply the lower NICE thresholds (overweight ≥23, obese ≥27.5) for South Asian, Chinese and other groups. NICE (2023) also advises using waist-to-height ratio (waist ÷ height, kept below 0.5) alongside BMI in adults with a BMI under 35 to assess central adiposity.
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NEWS2 — National Early Warning Score 2
Six physiological parameters + a supplemental-O₂ weighting. Triggers an escalation response.
📖 Notes
💡 Why we use it
- The single early-warning score used across the NHS — aggregates six bedside observations into one number to catch deterioration early.
- Drives a graded escalation response, so unwell patients are reviewed faster and sepsis isn’t missed.
- Objective and standardised — the same trigger thresholds on every ward.
📊 What the result means
0 — Routine — minimum 12-hourly observations.
1–4 (low) — Ward-nurse assessment; decide monitoring frequency.
3 in any one parameter — Urgent review even if the total is low.
5–6 (medium) — Urgent review by a clinician who can escalate; consider critical care.
≥7 (high) — Emergency assessment, continuous monitoring, usually critical-care input.
Add 2 points for any supplemental oxygen. Use SpO₂ Scale 2 only in confirmed chronic type 2 respiratory failure (e.g. COPD with a target 88–92%).
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GCS — Glasgow Coma Scale
Eye (4) + Verbal (5) + Motor (6). Min 3, Max 15.
📖 Notes
💡 Why we use it
- Objective, reproducible measure of conscious level after head injury, overdose, stroke or sepsis.
- Its real power is the trend — a falling GCS signals deterioration and prompts re-imaging or escalation.
- Gives a shared language (E, V, M) for handover and referral.
📊 What the result means
13–15 — Mild (15 = fully conscious).
9–12 — Moderate impairment.
≤8 — Severe — unable to protect the airway → consider intubation.
Always report the breakdown (e.g. E3 V4 M5 = 12), not just the total — the motor score is the strongest predictor of outcome. If a component can’t be tested, record it (intubated → VT; eyes swollen shut → EC) rather than guessing.
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IBW / ABW — Ideal & Adjusted Body Weight
Devine formula. ABW = IBW + 0.4×(actual − IBW) when obese.
📖 Notes
💡 Why we use it
- Estimates a height- and sex-based “physiological” weight (Devine formula) for tasks where actual weight over- or under-doses.
- Drives lung-protective ventilation — tidal volumes are set at 6–8 mL/kg of ideal body weight, not actual weight.
- Adjusted Body Weight (ABW) corrects IBW upward in obesity for drugs that partly distribute into fat.
📊 What the result means
- Use IBW for ventilator tidal volumes and many hydrophilic / renally-cleared drugs.
- Use ABW when BMI >30 for selected drugs (e.g. aminoglycosides).
- Some drugs use actual or total body weight (e.g. treatment-dose LMWH); others use body surface area (most chemotherapy) — always check the specific agent.
This is a dosing weight, not a measure of health or body fat — for that, use BMI.
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BSA — Body Surface Area (Mosteller)
BSA = √(H×W/3600). Used for chemotherapy dosing.
📖 Notes
💡 Why we use it
- Scales dose and physiology to overall body size better than weight alone (Mosteller: √(height×weight/3600)).
- Used to dose chemotherapy (mg/m²), index cardiac output (cardiac index = CO/BSA), and calculate paediatric maintenance fluids (burns use % TBSA).
📊 What the result means
- Normal adult ≈ 1.7 m² (≈1.9 m² male, ≈1.6 m² female).
- Higher BSA → higher absolute drug dose; indexing (per m²) compares people of different sizes fairly.
- It’s a formula-based estimate — clinical judgement and drug-specific dose caps still apply.
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MAP — Mean Arterial Pressure
MAP = DBP + ⅓(SBP − DBP). Minimum 65 mmHg for organ perfusion.
📖 Notes
💡 Why we use it
- Represents the average pressure driving blood into the organs across the whole cardiac cycle — a better perfusion marker than systolic pressure alone.
- MAP ≥65 mmHg is the usual resuscitation target to keep the brain and kidneys perfused in shock and sepsis.
- Guides vasopressor titration in critical care.
📊 What the result means
≥70 — Adequate organ perfusion pressure.
65–69 — Low — monitor closely.
<65 — Below the usual shock threshold; organs at risk → fluids / vasopressors.
MAP ≈ DBP + ⅓(SBP−DBP) — diastole dominates because the heart spends ~⅔ of the cycle in diastole. Targets are individualised: higher (≥80–85) in chronic hypertension or acute brain/cord injury. The ⅓ estimate underestimates MAP at fast heart rates — prefer an arterial-line MAP when available.
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CHA₂DS₂-VASc — AF Stroke Risk
Stroke risk in non-valvular AF. Guides anticoagulation.
Criteria
📖 Notes
💡 Why we use it
- Estimates annual ischaemic-stroke risk in non-valvular atrial fibrillation to decide who benefits from anticoagulation.
- The NICE/ESC gatekeeper for starting a DOAC (or warfarin).
- Simple, validated and points-based (CHF, Hypertension, Age, Diabetes, Stroke, Vascular disease, Sex).
📊 What the result means
0 (men) / 1 (women, sex point only) — Low — anticoagulation not recommended.
1 (men) — Consider anticoagulation, weighing bleeding risk.
≥2 (men) / ≥3 (women) — Anticoagulation recommended — offer a DOAC. The female sex point is discounted: a woman scoring 2 from one real risk factor sits in the “consider” zone.
Pair with a bleeding-risk score (HAS-BLED / ORBIT) — a high bleeding score prompts you to correct modifiable factors, not to withhold anticoagulation. A female sex point alone (score 1) does not warrant treatment.
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HAS-BLED — Bleeding Risk in AF
1-year major bleeding risk. Score ≥3 = high risk.
Risk Factors
📖 Notes
💡 Why we use it
- Estimates 1-year major-bleeding risk in AF patients on anticoagulation.
- Used alongside CHA₂DS₂-VASc — to flag and correct modifiable bleeding risks and set review frequency, not to deny anticoagulation.
- Points for Hypertension, Abnormal renal/liver function, Stroke, Bleeding history, Labile INR, Elderly, Drugs/alcohol.
📊 What the result means
0–1 — Low bleeding risk.
2 — Moderate bleeding risk.
≥3 — High risk — address reversible factors and review more often.
A high score is NOT a contraindication to anticoagulation — most patients still benefit. Modifiable factors: uncontrolled BP, labile INR, concurrent NSAIDs/antiplatelets, and alcohol excess. NICE NG196 now recommends the ORBIT score to assess bleeding risk, though HAS-BLED remains widely used.
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ORBIT — Bleeding Risk in AF
Major-bleeding risk on anticoagulation. NICE NG196’s preferred bleeding score.
Risk Factors
📖 Notes
💡 Why we use it
- Estimates major-bleeding risk in AF patients on, or being considered for, anticoagulation.
- NICE NG196 recommends ORBIT to assess bleeding risk — used alongside CHA₂DS₂-VASc to flag and correct modifiable risks, not to withhold anticoagulation.
- Five factors: older age, reduced haemoglobin/anaemia, bleeding history, insufficient renal function, and antiplatelet use.
📊 What the result means
0–2 — Low risk (≈2.4 major bleeds / 100 patient-years).
3 — Medium risk (≈4.7 / 100 patient-years).
4–7 — High risk (≈8.1 / 100 patient-years).
A high score is NOT a contraindication to anticoagulation — correct modifiable factors (treat anaemia, review the need for an antiplatelet, control BP) and review more often. Reduced haemoglobin/anaemia and bleeding history each score 2.
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GRACE — ACS In-Hospital Mortality
Estimates in-hospital death risk after ACS.
Additional
📖 Notes
💡 Why we use it
- Risk-stratifies NSTEMI / ACS by estimating in-hospital and 6-month mortality.
- Drives the timing of invasive coronary angiography — higher risk means earlier intervention (NICE).
- More discriminating than clinical judgement for the intermediate-risk patient.
📊 What the result means
<109 — Low risk (<1% in-hospital mortality).
109–139 — Intermediate risk (1–3%) → angiography within 72 h (NICE).
≥140 — High risk (>3%) → invasive angiography within 72 h (NICE NG185); ESC suggests within 24 h.
Uses age, heart rate, BP, creatinine, Killip class, cardiac arrest at presentation, ST deviation and enzyme rise. It guides timing — the decision to treat ACS still stands on its own. This tool uses the classic integer nomogram (an approximation); for high-stakes decisions confirm with the official GRACE 2.0 calculator (gracescore.org), which uses the continuous model.
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CURB-65 — CAP Severity
Severity scoring for community-acquired pneumonia.
Criteria
📖 Notes
💡 Why we use it
- Grades the severity of community-acquired pneumonia to guide the site of care (home vs ward vs ICU).
- Predicts 30-day mortality from five simple variables — Confusion, Urea >7, RR ≥30, BP low, age ≥65.
- Quick, objective triage that reduces unnecessary admissions and flags severe cases early.
📊 What the result means
0–1 — Low (<3% mortality) — consider home treatment.
2 — Intermediate (~9%) — consider hospital / short-stay.
3–5 — High (15–40%) — admit; 4–5 consider ICU.
A guide, not a substitute for clinical judgement or social factors. CRB-65 (drops urea) can be used in the community. Higher scores also steer broader-spectrum antibiotics.
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Wells Score — DVT
Pre-test probability of deep vein thrombosis.
Criteria
📖 Notes
💡 Why we use it
- Estimates the pre-test probability of deep vein thrombosis to choose the right pathway (D-dimer vs ultrasound).
- Prevents unnecessary scanning in low-probability patients and avoids missing high-probability ones.
📊 What the result means
≤1 — DVT unlikely (~6%) — D-dimer; if negative, DVT excluded.
≥2 — DVT likely (~28%) — proximal leg vein ultrasound within 4 h (or D-dimer + interim anticoagulation if the scan is delayed).
This is the NICE two-level Wells score (NG158), using the modified criteria that include previously documented DVT. Subtract 2 if an alternative diagnosis is at least as likely as DVT.
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Wells PE — Pulmonary Embolism
Score >4 = PE likely; ≤4 = PE unlikely.
Criteria
📖 Notes
💡 Why we use it
- Estimates the pre-test probability of pulmonary embolism to guide D-dimer vs CT pulmonary angiogram.
- Standardises the "is this PE?" decision and supports safe rule-out (with D-dimer) in unlikely patients.
📊 What the result means
≤4 — PE unlikely — D-dimer; if negative, PE excluded (consider age-adjusted D-dimer).
>4 — PE likely — proceed to CTPA (or V/Q if contrast contraindicated).
This is the 2-level Wells. In the 3-level model: <2 low, 2–6 intermediate, >6 high. Give interim anticoagulation if imaging is delayed and PE is likely.
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sPESI — PE Severity Index
30-day mortality in confirmed PE. Score 0 = low risk (~1%).
Risk Factors (1 point each)
📖 Notes
💡 Why we use it
- Risk-stratifies confirmed PE for 30-day mortality to decide inpatient vs outpatient/ambulatory management.
- Identifies low-risk PE suitable for early discharge.
- Six equally-weighted criteria: age >80, cancer, chronic cardiopulmonary disease, HR ≥110, SBP <100, SpO₂ <90%.
📊 What the result means
0 — Low risk (~1% 30-day mortality) — consider outpatient/ambulatory management.
≥1 — High risk (~10.9%) — admit; assess RV strain and monitor.
Only apply once PE is confirmed and the patient is haemodynamically stable — massive/high-risk PE with shock bypasses this and needs immediate reperfusion. Add RV assessment (echo, troponin) for the intermediate group. Low risk supports outpatient/ambulatory management only alongside wider suitability — acceptable bleeding risk, good social support and adequate follow-up (e.g. Hestia criteria).
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qSOFA — Sepsis Screening
Score ≥2 suggests high risk for poor outcome.
Criteria (1 point each)
📖 Notes
💡 Why we use it
- Rapid bedside screen flagging patients with suspected infection at higher risk of a poor outcome (death, prolonged ICU stay).
- Prompts escalation, senior review and a full sepsis work-up — needs no lab tests.
- Three criteria: RR ≥22, altered mentation (GCS <15), SBP ≤100.
📊 What the result means
0–1 — Lower risk — keep monitoring; don’t override clinical concern.
≥2 — High risk of poor outcome → investigate for organ dysfunction, escalate, consider Sepsis-6.
A prognostic prompt, not a diagnosis of sepsis and not a rule-out — a low score does not exclude sepsis. Many systems now prefer NEWS2 for screening; sepsis itself is defined by a rise in the full SOFA score.
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SOFA — Sequential Organ Failure Assessment
Organ dysfunction scoring in ICU. Score 0–24.
📖 Notes
💡 Why we use it
- Quantifies organ dysfunction across six systems — respiratory, coagulation, liver, cardiovascular, CNS and renal.
- An acute rise of ≥2 points in a patient with suspected infection defines sepsis (Sepsis-3).
- Tracks severity and trajectory in critical illness and correlates with mortality.
📊 What the result means
<6 — Lower predicted mortality (<10%).
6–9 — Moderate (~15–20%).
≥10 — High (40–50%+), rising with the score.
Sepsis = suspected infection + acute SOFA rise ≥2 from baseline (assume 0 if no known organ dysfunction). It grades severity — use qSOFA or NEWS2 to screen, not this.
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Alvarado Score — Appendicitis
Probability of acute appendicitis. Score ≥7 = high.
MANTRELS Criteria
📖 Notes
💡 Why we use it
- Scores the likelihood of acute appendicitis from history, examination and bloods to guide imaging and surgical referral.
- Helps triage right iliac fossa pain — who can be safely observed vs who needs urgent imaging/surgery.
- Mnemonic MANTRELS: Migration, Anorexia, Nausea, Tenderness RIF, Rebound, Elevated temperature, Leukocytosis, Shift of WBCs.
📊 What the result means
1–4 — Low probability — consider discharge / alternative diagnosis.
5–6 — Equivocal — observe, reassess, consider imaging.
7–10 — High probability — surgical review ± imaging.
Less reliable in women (gynae mimics) and children; imaging (US/CT) is increasingly used. A low score does not fully exclude appendicitis — safety-net and reassess.
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Glasgow-Blatchford — Upper GI Bleed
Predicts need for intervention. Score 0 = low risk.
Additional
📖 Notes
💡 Why we use it
- Pre-endoscopy score predicting the need for intervention (transfusion, endoscopic therapy, surgery) in upper GI bleeding.
- Its key use is identifying very-low-risk patients safe for outpatient management.
- Uses urea, haemoglobin, systolic BP, pulse, melaena, syncope and liver/cardiac disease — no endoscopy required.
📊 What the result means
0 — Very low risk — consider discharge with outpatient endoscopy.
1–5 — Intermediate — admit for inpatient endoscopy.
≥6 — High risk of needing intervention — resuscitate and scope urgently.
A score of 0 is the validated threshold for safe non-admission (some units use ≤1). It predicts need for intervention, not mortality — for rebleed/death risk use the Rockall score.
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Rockall Score — GI Bleed Rebleed Risk
Post-endoscopy rebleed and mortality risk. ≥5 = high.
📖 Notes
💡 Why we use it
- Predicts rebleeding and mortality after an upper GI bleed.
- The full (post-endoscopy) score adds the endoscopic findings; a pre-endoscopy version uses age, shock and comorbidity.
- Guides level of care and follow-up after the bleed.
📊 What the result means
≤2 — Low risk — good prognosis, consider early discharge.
3–4 — Intermediate — inpatient management.
≥5 — High risk of rebleeding/death — intensive monitoring.
Complements Glasgow-Blatchford: Blatchford triages BEFORE endoscopy (who needs intervention), Rockall estimates rebleed/mortality (mainly AFTER endoscopy).
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eGFR — CKD-EPI (2021)
Race-free 2021 equation. Used for CKD staging.
📖 Notes
💡 Why we use it
- Estimates glomerular filtration rate from serum creatinine to stage chronic kidney disease and guide management.
- The 2021 CKD-EPI equation is race-free (the Black-race coefficient was removed).
- Standardised staging (G1–G5) drives referral, monitoring frequency and nephrotoxin avoidance.
📊 What the result means
≥90 (G1) / 60–89 (G2) — Normal or mildly reduced — CKD only if other markers of kidney damage.
45–59 (G3a) / 30–44 (G3b) — Mild–moderate to moderate–severe reduction.
15–29 (G4) / <15 (G5) — Severe reduction / kidney failure — plan for renal replacement.
Not valid in AKI, extremes of muscle mass, pregnancy or rapidly changing creatinine. Stage CKD with eGFR AND albuminuria (ACR). Some drugs still dose on Cockcroft-Gault, not eGFR.
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Cockcroft-Gault — Creatinine Clearance
CrCl for drug dosing. Not for CKD staging.
📖 Notes
💡 Why we use it
- Estimates creatinine clearance for drug dosing — many drug licences and renal dose adjustments are still based on this equation, not eGFR.
- Incorporates actual weight and age, so it matters at extremes of body size.
- The reference method for dosing DOACs, aminoglycosides and many renally-cleared drugs.
📊 What the result means
≥60 mL/min — Adequate clearance — standard dosing for most drugs.
30–59 — Moderately reduced — check drug-specific dose adjustments.
<30 — Severely reduced — major dose reductions / avoid certain drugs (<15 approaches failure).
Use for DRUG DOSING, not CKD staging (use eGFR for that). Based on actual body weight — consider ideal/adjusted weight in obesity; it overestimates in low muscle mass.
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FENa — Fractional Excretion of Sodium
Distinguishes pre-renal (<1%) from intrinsic AKI (>2%).
📖 Notes
💡 Why we use it
- Distinguishes pre-renal AKI (kidneys avidly retaining sodium) from intrinsic renal injury (acute tubular necrosis, where damaged tubules leak sodium).
- Helps decide whether the kidney is under-perfused (give fluids) or intrinsically injured.
- Uses paired serum and urine sodium and creatinine.
📊 What the result means
<1% — Pre-renal AKI (or hepatorenal) — sodium avidly retained; treat the cause / fluids.
1–2% — Indeterminate.
>2% — Intrinsic renal failure (ATN) — tubules leaking sodium.
NOT valid on diuretics (falsely raises FENa) — use FEUrea instead (<35% suggests pre-renal). Also unreliable in CKD, contrast nephropathy and glomerulonephritis.
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Anion Gap — Metabolic Acidosis
AG = Na − (Cl + HCO₃). Normal 8–12 mEq/L.
📖 Notes
💡 Why we use it
- Identifies unmeasured anions in a metabolic acidosis, splitting it into high- vs normal-anion-gap causes.
- Narrows the differential fast: high gap (lactate, ketones, renal failure, toxins) vs normal gap (GI/renal bicarbonate loss).
- Albumin correction is essential — a low albumin masks a true gap.
📊 What the result means
8–12 mmol/L — Normal anion gap.
>12 (corrected) — High-anion-gap acidosis — MUDPILES (methanol, uraemia, DKA, propylene glycol, iron/INH, lactate, ethylene glycol, salicylates).
A normal-gap acidosis (with low bicarbonate) points to GI or renal bicarbonate loss (diarrhoea, renal tubular acidosis). Always correct for albumin: add ~2.5 mmol/L per 10 g/L that albumin is below 40. Check the osmolar gap if a toxic alcohol is suspected.
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Corrected Ca²⁺ — Albumin-adjusted
Corrected Ca = Measured + 0.02×(40 − Albumin).
📖 Notes
💡 Why we use it
- Nearly half of serum calcium is bound to albumin, so a low albumin reads calcium falsely low (and a high albumin falsely high).
- Correcting for albumin gives a truer estimate when an ionised calcium isn’t available.
- Prevents missed hypo-/hypercalcaemia in hypoalbuminaemic patients (sick, malnourished, nephrotic).
📊 What the result means
<2.20 mmol/L — Hypocalcaemia — paraesthesia, tetany, long QT.
2.20–2.60 — Normal.
2.60–3.00 — Mild hypercalcaemia.
3.00–3.40 — Moderate hypercalcaemia.
>3.40 — Severe hypercalcaemia — emergency (IV fluids ± bisphosphonate).
Correction: add 0.02 mmol/L per 1 g/L that albumin is below 40. Ionised (free) calcium is the gold standard — use it directly when available (critically ill, acid–base disturbance); correction is only an approximation.
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Serum Osmolality
Calc = 2×Na + Urea + Glucose. Normal 275–295 mOsm/kg.
📝 Notes & interpretation▾
💡 Why we use it
- Calculates expected serum osmolality (2×Na + urea + glucose); compared with a measured value it reveals the OSMOLAR GAP.
- A raised osmolar gap flags unmeasured osmoles — classically toxic alcohols (methanol, ethylene glycol) — a can’t-miss poisoning.
- Also helps work up hyponatraemia (true vs pseudo / hyperosmolar).
📊 What the result means
275–295 mOsm/kg — Normal calculated osmolality.
<275 or >295 — Hypo-/hyperosmolar — guides the Na⁺ workup.
Osmolar gap >10 — Unmeasured osmoles → toxic alcohol until proven otherwise.
The osmolar gap needs a lab-measured osmolality (gap = measured − calculated). A normal gap does not fully exclude early toxic-alcohol ingestion — correlate with the anion gap and clinical picture.
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A-a Gradient — Alveolar-Arterial O₂
Normal < age/4 + 4 mmHg. Elevated suggests V/Q mismatch.
📝 Notes & interpretation▾
💡 Why we use it
- Quantifies the difference between alveolar and arterial oxygen — separating hypoxaemia caused by the lungs from a non-lung cause.
- Localises the problem: a normal gradient points to hypoventilation or low inspired O₂; a raised gradient to a gas-exchange defect.
- Derived from the alveolar gas equation.
📊 What the result means
Normal (< age/4 + 4 mmHg) — Hypoxia from hypoventilation or low FiO₂ — the lungs are exchanging normally.
Elevated — Gas-exchange problem — V/Q mismatch (PE, pneumonia), shunt or diffusion impairment.
Enter PaO₂ and PaCO₂ in mmHg, NOT kPa — UK ABGs report in kPa, so convert first (kPa × 7.5 ≈ mmHg). The normal gradient rises with age (≈ age/4 + 4 mmHg on room air) and with higher FiO₂. Distinguish shunt from V/Q mismatch by the response to 100% O₂ — a shunt barely improves.
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Child-Pugh Score — Cirrhosis Severity
Class A: ~100%, B: ~80%, C: ~45% 1-yr survival.
📝 Notes & interpretation▾
💡 Why we use it
- Grades the severity of chronic liver disease / cirrhosis and predicts survival.
- Guides prognosis, surgical and anaesthetic risk, and eligibility for procedures (TIPS, resection).
- Uses bilirubin, albumin, INR, ascites and encephalopathy.
📊 What the result means
Class A (5–6) — Well-compensated — ~1-year survival ~100%.
Class B (7–9) — Significant compromise — ~1-year survival ~80%.
Class C (10–15) — Decompensated — ~1-year survival ~45%.
Two variables (ascites, encephalopathy) are subjective. MELD is now preferred for transplant prioritisation and acute prognosis, but Child-Pugh remains widely used for surgical risk.
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MELD — End-Stage Liver Disease
90-day mortality; transplant waitlist prioritisation.
📝 Notes & interpretation▾
💡 Why we use it
- Predicts 90-day mortality in end-stage liver disease from objective lab values (bilirubin, INR, creatinine ± sodium).
- Predicts waiting-list mortality and prioritises transplant candidates internationally — but note the UK (NHS Blood & Transplant) uses UKELD for liver transplant listing, not MELD.
- More objective than Child-Pugh — all numbers, no clinical judgement.
📊 What the result means
<10 — Low (~2% 3-month mortality).
10–19 — Intermediate.
≥20 — High and rising steeply (≥40 ≈ 70–100%).
MELD-Na adds sodium (hyponatraemia worsens prognosis). Also used for peri-operative risk in cirrhosis and transplant-referral timing. Not validated in acute liver failure.
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Maddrey’s DF — Alcoholic Hepatitis
DF ≥32 = severe (consider prednisolone 40mg/day).
📝 Notes & interpretation▾
💡 Why we use it
- A discriminant function that grades the severity of alcoholic hepatitis and the likely benefit of corticosteroids.
- Identifies severe disease with high short-term mortality who may benefit from steroids.
- Uses prothrombin time (vs control) and bilirubin.
📊 What the result means
<32 — Mild–moderate — good short-term prognosis; steroids not indicated.
≥32 — Severe alcoholic hepatitis — high 30-day mortality (~30–50%); consider corticosteroids if no contraindication.
Exclude/treat sepsis and GI bleeding before steroids. Reassess with the Lille score at day 7 — poor responders should stop steroids. GAHS and MELD are alternative severity scores.
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Maintenance Fluids & Parkland Formula
Holliday-Segar maintenance + Parkland burns.
📝 Notes & interpretation▾
💡 Why we use it
- Calculates daily maintenance fluid needs (Holliday-Segar 4-2-1 rule) and burns resuscitation (Parkland).
- Prevents both under- and over-hydration — critical in children, where dosing is weight-based.
- Standardises routine IV-fluid prescribing.
📊 What the result means
- Holliday-Segar (maintenance): 4 mL/kg/h for the first 10 kg + 2 mL/kg/h for the next 10 kg + 1 mL/kg/h for each kg above 20.
- Parkland (burns): 4 mL × weight (kg) × %TBSA over 24 h — half in the first 8 h (from the time of the burn), half over the next 16 h.
- Titrate to response (urine output, clinical status), not to the formula alone.
Adult routine maintenance (NICE): ~25–30 mL/kg/day water, ~1 mmol/kg/day Na⁺/K⁺/Cl⁻ and ~50–100 g/day glucose. Parkland is a starting estimate — target urine output 0.5–1 mL/kg/h (more in children/electrical burns) and reassess.
🧩 Case practice5 scenarios
Free Water Deficit
Estimates the volume of free water needed to correct hypernatraemia (Na > 145 mmol/L). Correct slowly: no faster than 10 mmol/L per 24 h to avoid cerebral oedema.
📝 Notes & interpretation▾
💡 Why we use it
- Estimates the volume of free water needed to correct hypernatraemia (Na >145) back to target.
- Guides the replacement plan — how much water (oral or IV) to give.
- Total body water × (current Na ÷ target Na − 1).
📊 What the result means
- The result is the litres of free water to replace, on top of ongoing maintenance and losses.
- Correct slowly: lower Na by no more than ~10 mmol/L per 24 h to avoid cerebral oedema.
- Choose fluid by volume status: hypovolaemic → resuscitate with saline first, then free water; euvolaemic/hypervolaemic → 5% dextrose or water.
An estimate only — recheck sodium every 4–6 h and adjust. Chronic hypernatraemia (>48 h) needs the slowest correction, and ongoing insensible/urinary losses must be added to the deficit.
🧩 Case practice5 scenarios
Bishop Score — Cervical Ripening
Score ≥8 = favourable; induction likely to succeed.
📝 Notes & interpretation▾
💡 Why we use it
- Assesses cervical favourability before induction of labour — predicts the chance of a successful vaginal delivery.
- Guides whether to ripen the cervix first (prostaglandin/balloon) or go straight to amniotomy ± oxytocin.
- Scores dilatation, effacement, station, consistency and position.
📊 What the result means
≤5 (unfavourable) — Cervix not ready → cervical ripening recommended.
6–7 (intermediate) — Induction may succeed.
≥8 (favourable) — As likely to deliver vaginally as spontaneous labour → proceed with induction.
Thresholds vary slightly by guideline; ≥8 is broadly "favourable." A very low score predicts a longer induction and higher caesarean risk.
🧩 Case practice5 scenarios
EDD / Gestational Age
Naegele’s rule: LMP + 9 months + 7 days.
📝 Notes & interpretation▾
💡 Why we use it
- Calculates the estimated due date and current gestational age from the last menstrual period (Naegele’s rule) or a dating scan.
- Gestational age underpins nearly every obstetric decision — screening timing, viability, growth, and managing prematurity or post-dates.
📊 What the result means
- EDD (Naegele): LMP + 1 year − 3 months + 7 days (≈280 days / 40 weeks from LMP).
- Term = 37–42 weeks; <37 preterm; >42 post-term.
- A first-trimester ultrasound (crown-rump length) is more accurate than LMP and sets the EDD if they differ by more than ~5–7 days.
Assumes a regular 28-day cycle — adjust for cycle length, and prefer scan/IVF dating where LMP is uncertain. These dates set the whole antenatal timeline, so accuracy matters.
🧩 Case practice5 scenarios
AMT-10 — Abbreviated Mental Test Score
Quick cognitive screen. Score ≤6/10 suggests impairment.
Score 1 point for each correct answer
📝 Notes & interpretation▾
💡 Why we use it
- Quick 10-point cognitive screen to detect possible cognitive impairment or delirium in older adults.
- Rapid bedside triage — a low score prompts a fuller assessment.
- Ten simple items: age, time, address recall, year, place, recognition, DOB, a historical date, the monarch, and counting backwards.
📊 What the result means
8–10 — Normal cognition.
7 — Borderline — consider repeat / further assessment.
≤6 — Suggests cognitive impairment or delirium → investigate.
A screen, not a diagnosis — it doesn’t separate delirium from dementia, and is confounded by deafness, dysphasia, low education and language barriers. For delirium specifically the 4AT is preferred. (AMT-4 is a validated short version; CURB-65 defines confusion as AMT ≤8 or new disorientation.)
🧩 Case practice5 scenarios
ROSIER — Stroke Recognition
Score >0 = stroke likely. Sensitivity ~93%.
Subtract (−1 each)
Add (+1 each)
📝 Notes & interpretation▾
💡 Why we use it
- Recognition Of Stroke In the Emergency Room — separates acute stroke from mimics (hypoglycaemia, seizure, migraine).
- Speeds the pathway to imaging and thrombolysis/thrombectomy by flagging likely strokes.
- Points for face/arm/leg weakness, speech and visual-field defects; minus points for loss of consciousness/syncope and seizure.
📊 What the result means
>0 (1–5) — Stroke likely → urgent CT and stroke-team activation.
≤0 — Stroke unlikely — but does NOT exclude it; reassess and consider mimics.
Check a glucose FIRST — hypoglycaemia is a classic mimic. A negative ROSIER does not rule out stroke or TIA; clinical suspicion overrides the score. Used with FAST pre-hospital.
🧩 Case practice5 scenarios
CIWA-Ar — Alcohol Withdrawal
Score <10 mild; 10–15 moderate; >15 severe.
📝 Notes & interpretation▾
💡 Why we use it
- Quantifies the severity of alcohol withdrawal to guide symptom-triggered benzodiazepine dosing.
- Symptom-triggered therapy (dosing to the score) uses less benzodiazepine and shortens treatment vs fixed schedules.
- Rates 10 domains — nausea, tremor, sweats, anxiety, agitation, tactile/auditory/visual disturbance, headache and orientation.
📊 What the result means
<10 — Mild — monitor, usually no medication.
10–15 — Moderate — benzodiazepines indicated.
>15 — Severe — treat promptly; high risk of seizures and delirium tremens.
Needs a communicative, cooperative patient — unreliable if intubated, confused from another cause, or non-English-speaking. Give thiamine (Pabrinex) to prevent Wernicke’s. Rising scores despite treatment or autonomic instability suggest impending DTs.
🧩 Case practice5 scenarios