Knowra Calcitriol Calcitriol Calcitriol is the hormonally active form of vitamin D₃, produced mainly in the kidneys. It regulates calcium and phosphate balance by acting on the intestine, bone, and kidneys.
Cholecalciferol : Cholecalciferol, or vitamin D₃, is a fat-soluble vitamin made in skin after ultraviolet B exposure and obtained from some foods. Calcitriol is the active hormone produced through successive transformations of this precursor.
Calcium homeostasis : Calcium homeostasis is the regulation of calcium concentrations in blood and tissues. Calcitriol is one of the hormones that helps keep blood calcium within a narrow range.
Chronic kidney disease–mineral and bone disorder : Chronic kidney disease–mineral and bone disorder is a set of abnormalities in mineral metabolism and bone health caused by impaired kidney function. Damaged kidneys may produce less calcitriol, contributing to disturbed calcium, phosphate, and bone regulation.
Hypercalcemia : Hypercalcemia is an abnormally high concentration of calcium in the blood. Excess calcitriol can increase calcium absorption and contribute to this dangerous complication.
Calcidiol : Calcidiol, or 25-hydroxyvitamin D, is the main circulating form of vitamin D and the usual measure of vitamin D status. The liver converts cholecalciferol into this circulating intermediate before kidney activation.
Phosphate homeostasis : Phosphate homeostasis is the regulation of phosphate levels in blood and tissues. Calcitriol affects phosphate absorption and works within systems that balance phosphate with calcium.
Hypoparathyroidism : Hypoparathyroidism is inadequate production of parathyroid hormone, often causing low blood calcium and high phosphate. Calcitriol can help manage low calcium when absent parathyroid signaling reduces its production.
Hyperphosphatemia : Hyperphosphatemia is an abnormally high concentration of phosphate in the blood. Calcitriol can raise intestinal phosphate absorption, especially when kidney excretion is impaired.
CYP27B1 : CYP27B1 is an enzyme that converts 25-hydroxyvitamin D into 1,25-dihydroxyvitamin D, or calcitriol. This kidney enzyme performs the final activation step that produces calcitriol.
Kidney : The kidneys filter blood, remove waste, and regulate water, electrolytes, and acid–base balance. Kidney cells produce most circulating calcitriol by activating its precursor.
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