Guides

A step-by-step path through acid–base interpretation: start with the serum anion gap, correct it for albumin, check the delta ratio, verify the expected respiratory compensation, and turn to urine indexes for normal anion gap acidosis.

How the four kidney function calculators differ: CKD-EPI 2021 and MDRD estimate GFR for classifying chronic kidney disease, Cockcroft–Gault estimates creatinine clearance for drug dosing, and a 24-hour urine collection provides a direct timed clearance.

The weight-based rules behind maintenance fluids, sodium correction in hyponatremia and hypernatremia, and daily calorie requirements — how the estimates differ from one another and how to use them as planning numbers rather than prescriptions.

Which risk score answers which question: CHA₂DS₂-VASc and HAS-BLED balance stroke against bleeding in atrial fibrillation, GRACE and TIMI prognosticate acute coronary syndromes, HEART stratifies emergency chest pain, RCRI estimates perioperative cardiac risk, and DAPT weighs antiplatelet duration.

How qSOFA, SOFA, SIRS criteria, NEWS2, and the shock index fit into detecting sepsis and clinical deterioration — including the shift in sepsis definitions from SIRS to the Sepsis-3 qSOFA/SOFA framework.

The relationships among BMI, waist-to-hip ratio, body surface area, and the ideal, adjusted, and lean body weight equations — what each measures, the formula behind it (WHO, Mosteller, Devine, Boer), and how to choose a weight basis for a task.

How the CURB-65, CRB-65, and PSI/PORT scores stratify community-acquired pneumonia severity and support site-of-care decisions — what variables each uses and where its evidence comes from.

How the liver calculators divide the work: MELD and MELD-Na for transplant prognosis, Child-Pugh and ALBI for liver function, APRI, FIB-4, and the NAFLD Fibrosis Score for non-invasive fibrosis estimation, the Maddrey Discriminant Function for alcoholic hepatitis, and the SAAG for ascites.

How the Wells score for pulmonary embolism, the Wells score for deep vein thrombosis, and the PERC rule estimate pre-test probability of venous thromboembolism and guide D-dimer and imaging decisions.

The relationships among the laboratory lipid calculators — calculated LDL, non-HDL cholesterol, TC/HDL, ApoB/ApoA1, and the atherogenic index of plasma — and the metabolic markers TG/HDL, the TyG index, and metabolic syndrome criteria.

A tour of the paediatric scoring tools: Apgar for newborns, the Pediatric Glasgow Coma Scale and Pediatric Trauma Score, PECARN for head trauma, the Westley croup score, the Rochester criteria and Gorelick scale, PEWS, PALS hypotension thresholds, and BMI-for-age.

Pregnancy dating and fetal assessment tools: EDD and gestational age, Hadlock estimated fetal weight, the Bishop score, the biophysical profile, ACOG preeclampsia and HELLP criteria, magnesium sulfate dosing, obstetric blood loss, gestational weight gain, and the Edinburgh Postnatal Depression Scale.

How the PHQ-9, GAD-7, Epworth Sleepiness Scale, and STOP-BANG questionnaire screen for depression, anxiety, daytime sleepiness, and obstructive sleep apnoea risk — and why a screening result is not a diagnosis.

The respiratory physiology calculators: the A–a oxygen gradient, PaO₂/FiO₂ ratio, oxygen index, ROX index, and BODE index — what each measures about gas exchange, lung injury, or COPD prognosis.