Exam aid · Lab and clinical values

Normal Lab Values

Adult reference ranges for interpreting cases. Laboratories differ slightly, so exams usually test whether a value is high or low.

Tables to memorise

Cover the right-hand column and test yourself before checking.

Test	Approximate range / target
Fasting glucose	3.9–5.5 mmol/L (70–100 mg/dL)
Diabetes (fasting)	≥ 7.0 mmol/L (126 mg/dL)
HbA1c (diabetes)	≥ 6.5% (48 mmol/mol)
ALT	< 40 U/L
ALP	40–130 U/L
Total bilirubin	< 21 µmol/L (1.2 mg/dL)
Albumin	35–50 g/L
Total cholesterol (desirable)	< 5.2 mmol/L (200 mg/dL)
LDL (very high risk target)	< 1.4 mmol/L (55 mg/dL)
Uric acid	Men < 0.42 mmol/L (7 mg/dL)

Test	Approximate adult range
Haemoglobin (men)	13–17 g/dL
Haemoglobin (women)	12–15 g/dL
White cell count	4–11 × 10⁹/L
Platelets	150–400 × 10⁹/L
MCV	80–100 fL
Ferritin	Low < 15–30 µg/L suggests iron deficiency
INR (no anticoagulant)	0.8–1.2
INR target (AF, VTE)	2.0–3.0
INR target (mechanical mitral valve)	Commonly 2.5–3.5

Correct calcium for albumin: add 0.02 mmol/L for every g/L albumin below 40.
Hyperkalaemia above 6.5 mmol/L or with ECG changes is an emergency.
High TSH with low free T4 = primary hypothyroidism.
Low ferritin is diagnostic of iron deficiency; normal ferritin does not exclude it in inflammation.
pH < 7.35 with low HCO3⁻ = metabolic acidosis; with high PaCO2 = respiratory acidosis.
Haemolysed samples falsely raise potassium.

Potassium: 3.5 to 5 keeps the heart alive: Both hypo- and hyperkalaemia cause dangerous arrhythmias.
ROME: Respiratory Opposite (pH and PaCO2 move oppositely), Metabolic Equal (pH and HCO3⁻ move together).

Attempt MCQs on these topics while the sheet is fresh. Anything you get wrong goes to your incorrect list for the next round.