Plasma free ionized calcium

Plasma free ionized calcium refers to the fraction of total blood calcium that is not bound to proteins or anions—this "free" form is biologically active and essential for many physiological processes. It constitutes about half of the total circulating blood calcium. The body tightly regulates this parameter through hormones such as parathyroid hormone and vitamin D. Abnormalities in plasma free ionized calcium are associated with a range of clinical conditions including kidney disease, parathyroid disorders (such as hyperparathyroidism or hypoparathyroidism), certain cancers with paraneoplastic syndromes causing hypercalcemia or hypocalcemia, and critical illness. Measurement of this parameter is used diagnostically rather than therapeutically; it does not represent a molecular target like a receptor or enzyme but rather serves as an important clinical biomarker for underlying pathophysiology[1][2][3][4].\n\n**Note:** "Plasma free ionized calcium level" describes a laboratory measurement/physiological state—not a discrete molecular entity such as an enzyme or receptor. It should not be classified as a therapeutic target; thus **is_target** should be set to false and **is_incorrect** set to true if you are seeking canonical drug targets like receptors or enzymes[1].

Other names

Ionized calciumFree calciumUnbound calciumiCa²⁺

*For drugs affecting plasma free ionized calcium levels*:\n - Increase or decrease absorption of dietary calcium (e.g., vitamin D analogs increase absorption)\n - Inhibit bone resorption to lower plasma levels (e.g., bisphosphonates, calcitonin)[1][2]