Ionized Calcium Unit Converter

Ionized calcium (also called free calcium) is the portion of calcium in your blood that is not bound to proteins or other molecules. It represents about 50% of the total calcium circulating in your blood.

The remaining calcium is bound to proteins (mainly albumin, about 40%) or complexed with anions like phosphate and citrate (about 10%). Only the ionized fraction is biologically active and available for immediate use by your cells.

While total calcium is often measured as a screening test, ionized calcium provides a more accurate picture of your true calcium status, especially in patients with abnormal protein levels or acid-base imbalances.

Calcium enters the body through intestinal absorption from food and supplements. Blood calcium levels are tightly regulated by the parathyroid glands, kidneys, and bones working together under the control of parathyroid hormone (PTH) and vitamin D.