25-Hydroxy Vitamin D
Alternate Names : 25-OH Vitamin D
Definition A test that measures the amount of 25-hydroxy vitamin D in blood serum.
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Why is the Test Performed?
This test is used to determine if a patient has a deficiency or excess of vitamin D. 25 hydroxy vitamin D is the most accurate measure of vitamin D stores in the body.
25 hydroxy vitamin D is stored in the liver where it is converted from other forms of vitamin D either obtained from the diet or made in the skin by sunlight. 25 hydroxy vitamin D is then changed to its active form, 1,25 dihydroxy vitamin D in the kidney. This active form of vitamin D causes increases in calcium and phosphate by activity primarily on the intestines, kidney and bone.
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