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Vitamin D Assay - Serum

Vitamin D: The Sunshine Vitamin

Total Vitamin D (measured as 25-OH-D) generally refers to both its natural and synthetic forms. Vitamin D2 is synthetic, while D3 is naturally found in food and activated by sun exposure. To provide you with more complete information about your patients' intake, we measure both forms, 25-hydroxyvitamin D3 (cholecalciferol), and 25-hydroxyvitamin D2 (ergocalciferol).

Researchers have found that 41% of U.S. outpatients, ages 49-83, had low circulating 25-hydroxyvitamin D (25-OH-D) levels. Serum 25-OH-D rises by about 1 ng/mL (2.5 nmol/L) for every 100 IU of additional vitamin D each day.

Why should you measure Vitamin D?

  • Detect Toxicity: Too much vitamin D can lead to vascular calcification from hypervitaminosis D.
  • Detect Deficiency: Vitamin D regulates calcium and phosphorus absorption/resorption to maintain bone health. Insufficiency is linked to depression and Seasonal Affective Disorder. Recent studies have also linked low vitamin D levels with higher risk of heart attack, various cancers, and autoimmune diseases.
    Vitamin D deficiency and insufficiency were found quite prevalent in a recent study of subjects with osteopenia or osteoporosis.**
    • Vitamin D deficiency was found among:
      • 33% of subjects below 50 years of age
      • 31.1% of subjects over 50 years of age
    • Vitamin D insufficiency was found among 35.9% of all subjects.
  • Improve Impaired Function: Vitamin D is important in neurological autoimmune processes such as Multiple Sclerosis.
  • Prevent/Reduce Inflammation: Vitamin D upregulates apoptotic mechanisms in pro-inflammatory cells to arrest appropriately and prevent on-going inflammation that damages tissue.

What forms of Vitamin D do we measure?

We measure Total 25-hydroxyvitamin D, as well as 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3. While both forms of vitamin D can raise total vitamin D with daily dosing, synthetic vitamin D2 does not maintain vitamin D levels over time as well as natural sources of vitamin D. The measurement of both D3 and D2 provides the opportunity to evaluate vitamin D therapy against the backdrop of each person's exposure to various vitamin D sources.

Vitamin D is also included in our Fat-Soluble and ION Profiles!

** ”Vitamin D status in patients with osteopenia or osteoporosis - an audit of an
endocrine clinic," Kocjan T, Tan TM, et al, Int J Vitam Nutr Res, 2006; 76(5): 307-13