Davis's Lab & Diagnostic Tests

Calcium, Blood, Total and Ionized

Calcium, Blood, Total and Ionized is a topic covered in the Davis's Lab & Diagnostic Tests.

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Total and free calcium, Ca (total), unbound calcium (ionized), Ca++ (ionized), Ca2+ (ionized).

Common Use:
To investigate various conditions, such as hypercalcemia and hypocalcemia, related to abnormally increased or decreased calcium levels.

Serum collected in a red- or red/gray-top tube. Plasma collected in a green-top (heparin) tube is also acceptable.

Normal Findings:
(Method: Spectrophotometry for total calcium; ion-selective electrode for ionized calcium)

Calcium, total
AgeConventional UnitsSI Units (Conventional Units × 0.25)
Cord8.2–11.2 mg/dL2.1–2.8 mmol/L
0–10 d7.6–10.4 mg/dL1.9–2.6 mmol/L
11 d–2 yr9–11 mg/dL2.2–2.8 mmol/L
3–12 yr8.8–10.8 mg/dL2.2–2.7 mmol/L
13–18 yr8.4–10.2 mg/dL2.1–2.6 mmol/L
Adult8.2–10.2 mg/dL2.1–2.6 mmol/L
Adult older than 90 yr8.2–9.6 mg/dL2.1–2.4 mmol/L

Calcium, ionized
AgeConventional UnitsSI Units (Conventional Units × 0.25)
Whole blood
 0–11 mo4.2–5.84 mg/dL1.05–1.46 mmol/L
 1 yr–adult4.6–5.08 mg/dL1.15–1.27 mmol/L
 Adult4.12–4.92 mg/dL1.03–1.23 mmol/L
 1–18 yr4.8–5.52 mg/dL1.2–1.38 mmol/L
 Adult and older adult4.64–5.28 mg/dL1.16–1.32 mmol/L

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