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Synonyms: 1,25-dihydroxycholecalciferol
German: calcitriol

1 Definition

Calcitriol is defined as the double hydroxylated vitamin D3 which animal organisms can synthesize from cholesterol. The vitamin-like hormone belongs to the group of calciferols and is generated from calcidiol by attaching a second hydroxyl group to the C1-atom in the kidney.

2 Biochemistry

Calcitriol is the most effective form of vitamin D. It ensures the resorption of calcium from the intestines and kidney and for the incorporation of calcium rich hydroxylapatite into the bone matrix. Within the cell, calcitriol is bound to a particular receptor protein, the vitamin-D-receptor (VDR). The resulting vitamin-receptor-complex is transported into the nucleus. There, it changes the transcription of various hormone sensitive genes, and with it, the protein biosynthesis controlled by these.

3 Pathophysiology

Calcitriol deficiency can lead to osteoporosis. Elevated calcitriol levels lead to symptoms of hypercalcemia.


This page was last edited on 23 May 2016, at 10:23.

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