Calcium Ion Homeostasis

Calcium ion homeostasis refers to the tightly regulated process that maintains a steady state level of calcium ions (Ca²⁺) within cells and in the blood plasma. This regulation is essential for numerous physiological functions, including bone mineralization, muscle contraction, nerve impulse conduction, blood coagulation, cell division, and intracellular signaling. It involves the coordinated actions of the skeletal, endocrine, digestive, and urinary systems, primarily through the hormones parathyroid hormone (PTH), vitamin D₃ (calcitriol), and calcitonin. Dysregulation can lead to hypocalcemia or hypercalcemia, resulting in various clinical manifestations.

Drugs affect calcium homeostasis by modulating intestinal absorption, renal reabsorption, and bone resorption of calcium. Some drugs directly target PTH secretion or action, while others influence vitamin D metabolism or calcitonin release.