4th July 2024

Calcium

Diet is the predominant source of this predominantly extracellular cation. It is highly regulated owing to its role in skeletal mineralisation, muscle contraction and neurological transmission, as well as vascular haemostasis. Absorption in the intestine is primarily controlled by 1,23-dihydroxy vitamin D3 (the active form of vitamin D). Parathyroid hormone regulates its secretion in the distal tubule of the kidney and calcitonin reduces plasma levels through its action on bones.