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Electrolytes & Minerals

Calcium, Ionized

Normal range 4.6-5.3 mg/dL (1.15-1.33 mmol/L SI). Specimen: Serum or whole blood.

Also known as: free calcium, iCal.

4.6-5.3 mg/dLCritical value: read below

Reference range

Conventionalmg/dL
4.65.3
SImmol/L
1.151.33

Combined adult band. LabVals does not publish separate men's, women's, or pediatric ranges for Calcium, Ionized; those can be narrower than the band shown.

Calcium, Ionized reference range, specimen, and conversion details
SpecimenSerum or whole blood
Conventional range4.6-5.3 mg/dL
SI range1.15-1.33 mmol/L
Conversion factor×0.25 (conventional → SI)
Critical value< 3.2 or > 6.2 mg/dL
PanelElectrolytes & Minerals

Convert any Calcium, Ionized result between units on the unit converter.

What is the normal range for Calcium, Ionized?

The standard teaching reference range for Calcium, Ionized is 4.6-5.3 mg/dL in conventional units, or 1.15-1.33 mmol/L in SI units. This value is measured in serum or whole blood.

What is a critical Calcium, Ionized value?

For Calcium, Ionized, the commonly taught critical (panic) value is: < 3.2 or > 6.2 mg/dL. Critical results are reported to the provider immediately under your facility's policy.

Source: Adult reference values compiled from Pagana & Pagana, Mosby's Diagnostic and Laboratory Test Reference, and Fischbach & Dunning, A Manual of Laboratory and Diagnostic Tests. Reference ranges vary by laboratory, method, age, sex, and population - always use the range printed on the actual result.

At the bedside

Nursing considerations

  • The physiologically active fraction; unaffected by albumin, so preferred in critical illness.
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