Lab values
Normal Coagulation Lab Values
Adult reference ranges in US units with the SI equivalent. Ranges differ a little between labs; use your lab’s printed range.
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Heparin vs Warfarin: aPTT vs INR, HIT, Bridging, Antidotes and DOAC Reversal
| Test | US units | SI units | Notes |
|---|---|---|---|
| PT | 11–13.5 seconds | 11–13.5 seconds | |
| INR | 0.8–1.1 | 0.8–1.1 | Therapeutic on warfarin usually 2–3 |
| aPTT | 25–35 seconds | 25–35 seconds | Therapeutic on heparin 1.5–2 times control (label; many texts 1.5–2.5), or anti-Xa per protocol |
| Fibrinogen | 200–400 mg/dL | 2.0–4.0 g/L | |
| D-dimer | Below 0.5 mcg/mL (FEU) | Below 0.5 mg/L (FEU) |
Study the labs
- ABG Interpretation in 6 StepspH, PaCO₂, HCO₃⁻, compensation, anion gap and oxygenation, with worked examples
- Electrolyte ImbalancesNa, K, Ca, Mg and phos: normals, ECG clues, safe replacement, hyperkalemia steps
- Pediatric Assessment and EmergenciesPAT, vital signs, airway infections, febrile seizures, dehydration, arrest, choking and abuse
Other lab values
- Chemistry
- Hematology
- Arterial blood gas
- Liver and pancreas
- Cardiac
- Therapeutic drug levels
- Urine
- Pregnancy and postpartum
- Newborn
- Pediatric vital signs by age
- Pediatric labs that differ from adults
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Sources
- MedlinePlus Medical Encyclopedia ranges (National Library of Medicine, reviewed 2024–2026); ABIM laboratory reference ranges (January 2026) for hemoglobin, hematocrit and potassium; Merck Manual for ionized calcium; the heparin label for the aPTT target; ASHP/IDSA 2020 vancomycin guideline
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow your local protocols and medical direction.