Hematocrit (Hct)
CBCNormal range
M 42–52% · F 37–47%
SI: M 0.42–0.52 · F 0.37–0.47
Critical low: < 21% · Critical high: > 60%
☎ When to call
Same triggers as hemoglobin — the two travel together. Escalate the pair, not one alone.
What you do
- Rule of thumb: Hct ≈ 3 × Hgb — a mismatch suggests lab error or acute change
- Interpret with volume status: a dehydrated bleeder can look 'normal'
Causes of HIGH hematocrit
Causes of LOW hematocrit
Source: Pagana, Mosby's Manual of Diagnostic and Laboratory Tests, 7th ed.Reference only — verify against your facility's policy.
