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1,25-dihydroxyvitamin D3 in serum (serum calcitriol)

Indications: 1) differentiating primary hyperparathyroidism from hypercalcemia of malignancy 2) distinguishing vitamin D-dependent & vitamin D-resistant rickets 3) monitoring vitamin D status in patients with chronic renal failure 4) assessing compliance with calcitriol therapy Normal range: - 16-65 pg/mL (42-169 pmol/mL) Specimen: 1) serum or plasma (heparin) 2) stable at room temp for 72 hours 3) store frozen; stable indefinitely at -20 degrees C Increases: 1) calcinosis secondary to tumor 2) primary hyperparathyroidism 3) idiopathic hypercalciuria 4) sarcoidosis 5) tuberculosis 6) lymphoma (some cases) 7) normal growing children 8) pregnant & lactating women Decreases: 1) azotemic chronic renal failure* 2) hypoparathyroidism 3) pseudohypoparathyroidism 4) vitamin D-dependent rickets 5) vitamin D-resistant rickets (familial hypophosphatemia) 6) postmenopausal osteoporosis 7) tumor-induced osteomalacia 8) adolescents with insulin-requiring diabetes 9) suboptimal 1,25-dihydroxyvitamin D levels associated with increased mortality * 1,25-dihydroxyvitamin D3 is NOT detectable in serum of anephric patients. Method: - column chromatography with RIA Notes: - 1,25-dihydroxyvitamin D3 is NOT a good measure of overall vitamin D status

Related

calcitriol; 1,25-dihydroxycholcalciferol; 1,25-dihydroxyvitamin D3

General

1,25-dihydroxyvitamin D in serum

References

  1. Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
  2. Clinical Guide to Laboratory Tests, 3rd ed. Teitz ed., W.B. Saunders, 1995
  3. Prescriber's Letter 15(3): 2008 Prevention and treatment of vitamin D deficiency Detail-Document#: 240311 (subscription needed) http://www.prescribersletter.com
  4. Dobnig H et al, Independent association of low serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels with all-cause and cardiovascular mortality. Arch Intern Med 2008 Jun 23; 168:1340. PMID: 18574092
  5. Vitamin D, 1,25-Dihydroxy Laboratory Test Directory ARUP: 80385