999-Vitamin D

Course # DL-999: Vitamin D

by Les Revier BS, MBA, CLS, C(ASCP) - Senior Manager, UCSD Medical Center Laboratory, Retired - Program Director, San Diego Miramar College MLT Program

Approved for 2.0 CE
Level of Difficulty: Intermediate


Over the last decade, interest in vitamin D has exploded. This vitamin, previously known primarily for its importance in preventing the bone conditions of rickets in children and osteomalacia, the softening of the bones, in adults, has recently been recognized as having a substantially greater role in health. Vitamin D is now known to affect a variety of physiologic systems and increased intake has been linked to a number of favorable health outcomes and even to a reduction in overall mortality.

25-hydroxyvitamin D (25-OHD), vitamin D, determination is of diagnostic importance for the investigation of vitamin D deficiency and much more rarely, intoxication. Despite the name, vitamin D is a pre-hormone, being endogenously synthesized provided there is adequate sunlight. Its biological function, exerted through the active form 1,25 dihydroxyvitamin D3 (1,25-(OH)2D) is to maintain calcium and phosphate levels in the blood. In addition, vitamin D has important roles in immune regulation. This presentation will examine the role of vitamin D in calcium homeostasis, discuss recently proposed effects on other diseases and conditions, provide insight into current dosing, discuss vitamin D insufficiency, and describe the measuring of vitamin D.


Upon completion of this course the participant will be able to:

  1. Outline the role of vitamin D in calcium homeostasis and its effects in the body.
  2. Discuss the finding that the role of vitamin D insufficiency is much more widespread than previously thought.
  3. Discuss the factors that affect activation of vitamin D in the skin by sunlight.
  4. Outline the diseases vitamin D has been found to ameliorate
  5. List the current dosing recommendation for vitamin D
  6. Discuss the status of measuring vitamin D level
  7. List several dietary sources of vitamin D

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