Paediatric laboratory reference ranges
44 reference ranges across 9 groups. Values vary by laboratory, assay and age — always check the range printed on your own report.
Electrolytes & renal
| Test | Specimen | Reference range |
|---|
| Sodium | Plasma | 135–145 mmol/L |
|---|
| Potassium | Plasma | 3.5–5.0 mmol/L (neonate up to 6.0) |
|---|
| Chloride | Plasma | 98–106 mmol/L |
|---|
| Bicarbonate | Plasma | 22–26 mmol/L |
|---|
| Urea | Plasma | 2.5–6.5 mmol/L |
|---|
| Creatinine | Plasma | Infant 18–35; child 27–62 µmol/L (age-dependent) |
|---|
| Glucose (fasting) | Plasma | 3.5–5.5 mmol/L |
|---|
| Calcium (total) | Plasma | 2.2–2.7 mmol/L |
|---|
| Ionised calcium | Plasma | 1.1–1.3 mmol/L |
|---|
| Magnesium | Plasma | 0.7–1.0 mmol/L |
|---|
| Phosphate | Plasma | 1.3–2.3 mmol/L (higher in infants) |
|---|
More on electrolytes & renal →
Acid–base / gases
| Test | Specimen | Reference range |
|---|
| pH (arterial) | Blood gas | 7.35–7.45 |
|---|
| PaCO₂ | Blood gas | 35–45 mmHg (4.7–6.0 kPa) |
|---|
| PaO₂ | Blood gas | 80–100 mmHg (10.6–13.3 kPa) |
|---|
| Base excess | Blood gas | −2 to +2 mmol/L |
|---|
| Lactate | Blood | <2.0 mmol/L |
|---|
More on acid–base / gases →
Haematology
| Test | Specimen | Reference range |
|---|
| Haemoglobin | Blood | Newborn 14–22; 6 mo–6 yr 11–14; older 12–16 g/dL |
|---|
| White cell count | Blood | Neonate 9–30; infant 6–17; child 5–15 ×10⁹/L |
|---|
| Platelets | Blood | 150–400 ×10⁹/L |
|---|
| Neutrophils | Blood | 1.5–8.0 ×10⁹/L (age-dependent) |
|---|
| Reticulocytes | Blood | 0.5–1.5% (higher in newborn) |
|---|
More on haematology →
Coagulation
| Test | Specimen | Reference range |
|---|
| PT | Plasma | 11–14 s |
|---|
| aPTT | Plasma | 25–35 s |
|---|
| INR | Plasma | 0.9–1.2 |
|---|
| Fibrinogen | Plasma | 1.5–4.0 g/L |
|---|
| D-dimer | Plasma | <0.5 mg/L (assay-dependent) |
|---|
More on coagulation →
Liver
| Test | Specimen | Reference range |
|---|
| Bilirubin (total) | Plasma | <17 µmol/L (neonatal ranges differ) |
|---|
| ALT | Plasma | <40 U/L |
|---|
| AST | Plasma | <45 U/L (higher in infants) |
|---|
| ALP | Plasma | High in growth: up to ~400 U/L in children |
|---|
| GGT | Plasma | <55 U/L (high in neonates) |
|---|
| Albumin | Plasma | 35–50 g/L |
|---|
| Ammonia | Plasma | Neonate <110; child <50 µmol/L |
|---|
More on liver →
Inflammatory
| Test | Specimen | Reference range |
|---|
| CRP | Plasma | <10 mg/L |
|---|
| Procalcitonin | Plasma | <0.5 ng/mL |
|---|
| Ferritin | Plasma | Age/sex dependent; markedly ↑ in HLH |
|---|
| ESR | Blood | <15 mm/hr (varies) |
|---|
Endocrine
| Test | Specimen | Reference range |
|---|
| TSH | Plasma | 0.5–5.0 mU/L (higher in neonate) |
|---|
| Free T4 | Plasma | 12–22 pmol/L |
|---|
| Cortisol (0800h) | Plasma | 170–500 nmol/L |
|---|
CSF
| Test | Specimen | Reference range |
|---|
| CSF WCC | CSF | Child <5 ×10⁶/L; neonate up to ~20 |
|---|
| CSF protein | CSF | Child 0.15–0.4 g/L; neonate up to ~1.0 |
|---|
| CSF glucose | CSF | ≥2/3 of plasma glucose |
|---|
Cardiac
| Test | Specimen | Reference range |
|---|
| Troponin | Plasma | Assay-dependent; low in health |
|---|
About this page
Compiled from standard paediatric references. Interpret against the child's clinical state and the ranges used by your own institution or laboratory.
Spotted something wrong?
Report an error on this page —
corrections from clinicians are welcome and are reviewed before any change is published.
Last reviewed 2026-08-12.