Calcium ion (Ca2+) (Ca2+)

Calcium ions in the blood and plasma are essential divalent cations that serve as critical messengers and structural components within the human body. They are vital for physiological processes such as myocardial and skeletal muscle contraction, blood coagulation (acting as Factor IV), and the release of neurotransmitters at synaptic junctions (StatPearls: Physiology, Calcium). The concentration of ionized calcium is maintained within a narrow range through a complex homeostatic system involving the parathyroid hormone (PTH), vitamin D, and the calcium-sensing receptor (CaSR) (NIH: Calcium Fact Sheet). Clinical disorders arise when these levels deviate, with hypercalcemia potentially leading to renal failure and arrhythmias, while hypocalcemia can cause tetany and seizures (Merck Manual: Hypocalcemia). Therapeutic strategies include direct intravenous or oral supplementation to treat deficiencies, or the use of chelating agents like EDTA to manage toxicity or prevent clotting in vitro (PubChem: Calcium Gluconate). Additionally, drugs like cinacalcet and bisphosphonates are used to indirectly manage blood calcium levels by influencing bone turnover and hormonal signaling (FDA: Sensipar Label). Maintaining calcium homeostasis is vital for cardiovascular stability and skeletal integrity.

Other names

Serum calciumPlasma calciumIonized calciumCa++Calcium(2+)

Direct supplementation of elemental calcium to restore physiological levels, chelation of ionized calcium to reduce bioavailability or prevent coagulation, and indirect modulation of serum levels via the calcium-sensing receptor (CaSR) or inhibition of osteoclast-mediated bone resorption.