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Calcifediol, also known as calcidiol, 25-hydroxycholecalciferol, or 25-hydroxyvitamin D3 (abbreviated 25 (OH)D3), [1] is a form of vitamin D produced in the liver by hydroxylation of vitamin D 3 (cholecalciferol) by the enzyme vitamin D 25-hydroxylase. [3][4][5] Calcifediol can be further hydroxylated by the enzyme 25 (OH)D-1α-hydroxylase ...
Vitamin D deficiency is typically diagnosed by measuring the concentration of the 25-hydroxyvitamin D in the blood, which is the most accurate measure of stores of vitamin D in the body. [1][7][2] One nanogram per millilitre (1 ng/mL) is equivalent to 2.5 nanomoles per litre (2.5 nmol/L). Severe deficiency: <12 ng/mL = <30 nmol/L[2] Deficiency ...
A diet insufficient in vitamin D, combined with inadequate sunlight exposure, can lead to vitamin D deficiency, which is defined as a blood 25-hydroxyvitamin D or 25(OH)D level below 12 ng/mL (30 nmol/liter). Vitamin D insufficiency, on the other hand, is characterized by a blood 25(OH)D level between 12–20 ng/mL (30–50 nmol/liter).
Vitamin D toxicity. Cholecalciferol (shown above) and ergocalciferol are the two major forms of vitamin D. Specialty. Endocrinology, toxicology. Vitamin D toxicity, or hypervitaminosis D, is the toxic state of an excess of vitamin D. The normal range for blood concentration in adults is 20 to 50 nanograms per milliliter (ng/mL).
Cholecalciferol is a form of vitamin D which is naturally synthesized in skin and functions as a pro-hormone, being converted to calcitriol. This is important for maintaining calcium levels and promoting bone health and development. [4] As a medication, cholecalciferol may be taken as a dietary supplement to prevent or to treat vitamin D ...
CYP2R1 is cytochrome P450 2R1, an enzyme which is the principal vitamin D 25-hydroxylase. [5] [6] In humans it is encoded by the CYP2R1 gene located on chromosome 11p15.2. [7]It is expressed in the endoplasmic reticulum in liver, where it performs the first step in the activation of vitamin D by catalyzing the formation of 25-hydroxyvitamin D. [8]
These two forms of vitamin D are metabolized in the liver and stored as 25-hydroxyvitamin D. [4] Before biological use, the storage form must be converted into an active form. One common active form is 1,25-dihydroxyvitamin D. [ 4 ] The term vitamin D in this article means cholecalciferol, ergocalciferol, 25-hydroxyvitamin D, and the active forms.
Hyperparathyroidism is an increase in parathyroid hormone (PTH) levels in the blood. [1][4] This occurs from a disorder either within the parathyroid glands (primary hyperparathyroidism) or as response to external stimuli (secondary hyperparathyroidism). [1] Symptoms of hyperparathyroidism are caused by inappropriately normal or elevated blood ...