Active Vitamin D 1,25-dihydroxy active vitamin D - Finger prick
This blood test measures 1,25-dihydroxyvitamin D [1,25-(OH)â‚‚D]. This is the biologically active form of vitamin D and is also known as calcitriol.
This test is primarily intended for specific medical conditions, such as abnormalities in calcium metabolism, certain kidney diseases, or conditions in which the production of active vitamin D may be impaired.
What is active vitamin D?
Vitamin D is metabolized in the body in several steps. First, 25-hydroxyvitamin D (25-OH-vitamin D) is produced in the liver. This is the primary storage and circulating form of vitamin D.
25-OH-vitamin D is then converted, primarily in the kidneys, into 1,25-dihydroxyvitamin D, the active form. This conversion is regulated by, among other factors, parathyroid hormone (PTH), calcium, and phosphate.
Active vitamin D plays an important role in calcium and phosphate metabolism and, consequently, in bone metabolism, among other things.
When is active vitamin D tested?
A measurement of 1,25-dihydroxyvitamin D can, for example, be used in research on:
abnormal calcium levels;
disorders of calcium and phosphate metabolism;
certain kidney diseases;
abnormalities in parathyroid hormone (PTH) levels;
Sarcoidosis and other granulomatous disorders;
certain types of lymphoma;
Rare disorders of vitamin D metabolism.
The results are usually interpreted in conjunction with other values, such as calcium, phosphate, PTH, creatinine/eGFR, and 25-OH vitamin D.
Please note: Not suitable for diagnosing a standard vitamin D deficiency
Would you like to know if you have a vitamin D deficiency or check whether vitamin D supplementation is effective? In that case, the 25-OH-vitamin D test is usually the right blood test.
A normal or even elevated level of active vitamin D does not rule out a deficiency in 25-OH-vitamin D. This is because, in the event of a deficiency, the body may try to maintain its production of active vitamin D.
See the 25-OH-vitamin D test for more information.
