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Vitamin D, 25-Hydroxy

Item Value
Approval req'd? No
Available Stat? No
Test code 25HD
Performed by Parnassus Chemistry
In House Availability Test performed daily 0800-2400
Method Beckman Coulter DxI600 Chemiluminescent Immunoassay
Container type Gold top
Amount to Collect 3 mL blood
Sample type Serum
Preferred volume 1.5 mL serum
Min. Volume 0.5 mL serum
Processing notes Refrigerate serum aliquot
Units ng/mL
Normal range 20 - 50 ng/mL

25-OHD values < 20 are considered to be insufficient and values < 10 - 12 are associated with vitamin D deficiency and risk for osteomalacia. Although values of 20 or more are generally considered to be sufficient, values in the range of 20 - 30 may be insufficient in certain high risk patient subgroups. There is no known benefit of values > 50, and values > 100 should be avoided because of possible risk of vitamin D toxicity.
Synonyms 25-Hydroxycalciferol; 25-OH-D; Cholecalciferol Metabolite
Stability After separation from cells serum is stable at room temperature for 3 days, refrigerated 1 week and frozen at -20C 6 months.
Additional information To convert µg/L to nmol/L (SI units) multiply by 2.496.

Normal range cutoffs for screening are based on the Institute of Medicine (IOM) Committee's 2011 Report on Dietary Reference Intakes for Calcium and Vitamin D. For a discussion of the controversy regarding normal range cutoffs and the IOM recommendations, see Rosen C, et al. J Clin Endocrinol Metab 97: 1146–1152, 2012.
LOINC code 49054-0
Last Updated 9/4/2015 10:01:12 AM
Entry Number 1002
Lab Procedure Link Click here for Procedure
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