Toxicology

Vitamin D 25 Hydroxy Levels Methodology Update

Effective September 12, 2016, Spectrum Health Regional Laboratory (SHRL) will update the methodology for Vitamin D 25 Hydroxy Level (25-OH Vitamin D) from LCMS (Liquid Chromatography-Mass Spectrometry) to automated immunoassay.

SHRL performs approximately 5000 Vitamin D 25 Hydroxy Levels (25-OH Vitamin D) per month. This high volume, along with resources and cost, is driving the need to update our methodology to an automated assay. Notably, 40% of currently reported test results are Vitamin D sufficient (>29 ng/mL) suggesting that a large number of requests might be unnecessary in nature.

Both methods are clinically comparable based on literature and internal comparison studies. However, as part of this change, the interpretive range will be updated to reflect The Endocrine Society recommendations:

The Endocrine Society does not recommend population screening for Vitamin D deficiency in individuals who are not at risk.

  • “At risk” includes, but is not limited to, the following situations:
    • Older adults
    • Rickets
    • Osteoporosis
    • Chronic kidney disease
    • Malabsorption syndromes
    • Cystic Fibrosis

Endocrine Society recommended interpretive ranges

  • <20 ng/mL Vitamin D Deficient
  • 21-29 ng/mL Vitamin D Insufficient
  • >29 ng/mL Vitamin D Sufficient

Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, Murad MH, Weaver CM. Guidelines for preventing and treating vitamin D deficiency and insufficiency revisited. J Clin Endocrinol Metab. 2011.96:1911-1930

Results greater than 60 ng/mL will be reported as >60ng/mL (only 4% of currently reported results are in this range). Additionally, D2/D3 distinctions will no longer be reported. Requests for specific results >60 ng/mL or D2/D3 discrimination will be reviewed by our Associate Medical Directors and Pathologists, Dr. David Alter or Dr. Deborah Blue on a case by case basis.

For specimen collection instructions please review the laboratory catalog.

Questions and further inquiries may be directed to Dr. David Alter or Dr. Deborah Blue via the “Contact Us” link above.

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