Calcitriol (1,25-dihydroxylcholecaldiferol) is a steroid hormone with three hydroxyl groups, which is an active metabolite and the most effective form of vitamin D. It is produced primarily in the kidney when the blood calcium level and parathyroid hormone are low.
Calcitriol promotes the calcium and phosphorus absorption in the intestine, reabsorption in the kidneys. Along with parathyroid hormone, it regulates bone growth for building and keeping strong bones.
Calcitriol is used to treat and prevent low levels of calcium and bone disease in patients whose kidneys or parathyroid glands are not working normally, to treat secondary hyperparathyroidism and metabolic bone disease in people with kidney disease.
Calcitriol may also be chemopreventive for colon and prostate cancers as it induces cell cycle arrest, cell differentiation, and apoptosis.
