Vitamin D Assay - Serum

Most Vitamin D is stored in the body tissues as the 25-hydroxyvitamin D derivative (25-OH-D). The biologically active vitamin (1-alpha, 25-dihydroxyvitamin) D3 is produced locally in various tissues where it modulates calcium absorption and inflammatory responses. Total vitamin D nutritional status is indicated by serum (25-OH-D) measurement.

Why should you measure Vitamin D?

• Detect toxicity: You can take too much, leading to vascular calcification from hyperviatminosis D.
• Detect deficiency: Vitamin D regulates calcium and phosphorus absorption/resorption to maintain bone health.
  • Vitamin D deficiency and insufficiency were found quite prevalent in a recent study of subjects with osteopenia or osterporosis. Vitamin D deficiency was found among 33% of subjects below 50 years of age and 31.1% of subjects over 50 years of age. Vitamin D insufficiency was found among 35.9% of all subjects.**
  • Vitamin D insufficiency is linked to depression and Seasonal Affective Disorder.
• Vitamin D is important in neurological autoimmune processes like Multiple Sclerosis.
• Vitamin D upregulates apoptotic mechanisms in pro-inflammatory cells to arrest appropriately and preventing on-going inflammation that damages tissue.
• Recent studies have also linked low vitamin D levels with higher risk of heart attack, various cancers, and autoimmune diseases.

What form of Vitamin D are you measuring?

• Within hours, vitamin D from sunlight and diet is removed from circulation and recirculates again a few hours later as (25-OH-D). This form has the longest half life, about three weeks.
• (1, 25-OH)2D3)* is the more biologically active metabolite, but plasma concentrations are mainly dependent on renal function, appropriate parathyroid hormone levels, and the supply of calcium and phosphate. The levels of this metabolic decline only after vitamin depletion is virtually complete.

Vitamin D is also included in our ION Profiles!

*In various publications the term, "vitamin D3" has been used to identify the active form of vitamin D or its precursors.

**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