Serum Ionic Calcium

Serum Ionic Calcium, also known as ionized calcium, is a blood test that measures the amount of free, unbound calcium in the bloodstream—the form that is physiologically active. Unlike total calcium, which includes calcium bound to proteins like albumin, ionic calcium reflects the calcium that is readily available for vital body functions, such as muscle contraction, nerve signaling, blood clotting, and heart rhythm regulation. It is especially important in critically ill patients or those with abnormal protein levels. Abnormal ionized calcium levels can indicate conditions such as parathyroid disorders, kidney dysfunction, or calcium metabolism issues.