Markers › Ionized Calcium

Ionized Calcium

ElectrolytesBone & MuscleBlood

Ionized calcium is calcium in the blood that is not attached to proteins. It makes up about half of all the calcium in the blood. It is also called free calcium, because it is active and available for use. The rest of the calcium in the blood attaches to proteins, mostly albumin, and providers call that bound calcium because it is not active or available for use while it stays bound.

Why it matters: An ionized calcium test differs from a standard calcium blood test, which checks the total amount of calcium in the blood, both bound and free; an ionized calcium test measures only the free calcium. A provider might order one where there are abnormal levels of blood proteins such as albumin, a serious illness needing IV fluids, major surgery, blood transfusions, a pregnancy needing neonatal monitoring, symptoms of acute pancreatitis, or symptoms of a parathyroid disorder. Low ionized calcium might indicate hypoparathyroidism, pancreatitis, malabsorption, rickets, kidney failure or vitamin D deficiency. High ionized calcium could point to hyperthyroidism, hyperparathyroidism, Paget's disease of the bone, thrombocytosis, sarcoidosis or multiple myeloma.

Source · Cleveland Clinic — what it is, why it matters, related conditions

Reference Range
1.12 – 1.32mmol/L
1.12
1.32LowNormalHigh
Associated Conditions
Hypoparathyroidism, which a low level might indicatePancreatitis, which a low level might indicateMalabsorption, which a low level might indicateRickets, or soft bones in children, which a low level might indicateKidney failure, which a low level might indicateVitamin D deficiency, which a low level might indicateHyperthyroidism, which a high level could point toHyperparathyroidism, which a high level could point toPaget's disease of the bone, which a high level could point toThrombocytosis, which a high level could point toSarcoidosis, which a high level could point toMultiple myeloma, which a high level could point to
Related Markers
CalciumPTHVitamin DMagnesiumAlbumin
Common questions

What is Ionized Calcium?

Ionized calcium is calcium in the blood that is not attached to proteins. It makes up about half of all the calcium in the blood. It is also called free calcium, because it is active and available for use. The rest of the calcium in the blood attaches to proteins, mostly albumin, and providers call that bound calcium because it is not active or available for use while it stays bound.

What might a high or low Ionized Calcium mean?

An ionized calcium test differs from a standard calcium blood test, which checks the total amount of calcium in the blood, both bound and free; an ionized calcium test measures only the free calcium. A provider might order one where there are abnormal levels of blood proteins such as albumin, a serious illness needing IV fluids, major surgery, blood transfusions, a pregnancy needing neonatal monitoring, symptoms of acute pancreatitis, or symptoms of a parathyroid disorder. Low ionized calcium might indicate hypoparathyroidism, pancreatitis, malabsorption, rickets, kidney failure or vitamin D deficiency. High ionized calcium could point to hyperthyroidism, hyperparathyroidism, Paget's disease of the bone, thrombocytosis, sarcoidosis or multiple myeloma.

What is the typical reference range for Ionized Calcium?

The general-population reference range shown here is 1.12 – 1.32 mmol/L. Reference ranges describe the general population and are not a personal target — discuss your results with your physician.

More in Electrolytes
CalciumCalcium/Albumin RatioCalcium/Phosphorous RatioChlorideMagnesiumPhosphorusPotassiumPTHSodiumSodium/Potassium Ratio

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