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Ionized Calcium

Abbreviation: iCa

Panel: Metabolic, Kidney & Electrolytes · All metabolic & kidney tests

Typical adult reference range

Conventional units4.5–5.3 mg/dL
SI units1.12–1.32 mmol/L

Ranges vary between laboratories and methods — compare your result with the range printed on your own report.

What a high or low result can mean

High ionized calcium: high values can be seen in hyperparathyroidism and some cancers.

Low ionized calcium: low values may occur with vitamin D deficiency, hypoparathyroidism, or critical illness.

These are associations, not a diagnosis: the same result can have several causes, and your clinician interprets it with the rest of your results and history.

Good to know

Measures the physiologically active, unbound fraction of calcium.

◆ Kidney note

This test is closely tied to kidney health, and it is one a kidney specialist (nephrologist) watches closely. On this site, kidney-related results are a special focus: see the kidney and dialysis medicines in our Drug Guide and the kidney condition hubs for the wider picture.

Related tests — Metabolic, Kidney & Electrolytes

AlbuminAmylaseAnion GapBeta-HydroxybutyrateBicarbonateBlood Urea NitrogenBUN-to-Creatinine RatioCalcium, Total
Please note: Reference ranges vary between laboratories, and between the methods and instruments they use — the range printed on your own report is the one your result should be compared with. A result outside the range is not by itself a diagnosis, and a result inside it does not rule out illness. These pages are an educational summary, not medical advice: always discuss your results with the clinician who ordered them, who can interpret them in the context of your health and history.