Vitamin D promotes calcium absorption in the gut and maintains adequate serum calcium and phosphate concentrations to enable normal mineralization of bone. Without sufficient vitamin D, bones can become thin, brittle or misshapen. Vitamin D sufficiency prevents rickets in children and osteomalacia in adults.
Vitamin D is a fat-soluble vitamin that is naturally present in very few foods, added to others and is available as a dietary supplement. It is also produced endogenously when ultraviolet rays from sunlight strike the skin and trigger vitamin D synthesis. Vitamin D obtained from sun exposure, food and supplements is biologically inert and must undergo two hydroxylations in the body for activation. The first occurs in the liver and converts vitamin D to 25-hydroxyvitamin D [25(OH)D], also known as calcidiol. The second occurs primarily in the kidney and forms the physiologically active 1,25-dihydroxyvitamin D [1,25(OH)2D], also known as calcitriol
The question that you really want to know is, “What are optimal vitamin D levels?” Every laboratory has a “reference range” that is unique and depends upon many different factors. Often they take a range of “healthy” individuals and create an average range after excluding a certain percentage from the low range and the high range. Typically for vitamin D, that range is 30-100 ng/mL.
Having a lower than normal level of 25 hydroxy vitamin D indicates a vitamin D deficiency. This condition can result from lack of exposure to sunlight; lack of adequate vitamin D in the diet; liver and kidney diseases; malabsorption; or the use of certain medicines, including phenytoin, phenobarbital, and rifampin. Additional conditions include lactose-intolerant individuals that limit the consumption of milk products, babies solely breastfed (human breast mild does not contain a sufficient amount of vitamin D) and individuals who follow a vegetarian diet.
Low vitamin D levels have also been associated with an increased risk of developing cancer. Higher than normal levels suggest excess vitamin D, a condition called hypervitaminosis D.
If low vitamin D results in rickets you can recognize the disease by these symptoms:
• Bone pain or tenderness in the arms, legs, pelvis or spine
• Dental deformities
• Decreased muscle tone
• Impaired growth
• Skeletal deformities.
Treatment can eliminate most symptoms of rickets by replacing calcium, phosphorus or vitamin D. Dietary sources of vitamin D include fish, liver and processed milk. Exposure to moderate amounts of sunlight is encouraged. If a metabolic problem has caused rickets, a prescription for vitamin D supplements may be needed.
Treatment for vitamin D deficiency involves getting more vitamin D -- through diet, supplements and/or through spending more time in the sun. Although there is no consensus on vitamin D levels required for optimal health -- and it likely differs depending on age and health conditions -- a concentration of less than 20 nanograms per milliliter is generally considered inadequate, requiring treatment.
The 25 hydroxy vitamin D test for vitamin D deficiency is available for $45 at the Northern Nevada Medical Center health fair from 7:30 to 11 a.m. May 3. Visit the first floor of NNMC at 2375 E. Prater Way in Sparks.
Northern Nevada Medical Center holds these health fairs on the first Thursday of every month. You can receive complimentary blood pressure and body fat screenings; a lipid profile including cholesterol, triglycerides and HDL/LDL ratio; PSA prostate cancer testing; and other screenings. A physician or a nurse or both will be available to answer your questions.
For more information, visit www.nnmc.com and click on the link for Community Events.
John Miceli is the director of Ancillary Service at Northern Nevada Medical Center. Miceli has extensive experience in the area of cardiac catheterization and oversees the Accredited Chest Pain Center at NNMC. Miceli holds advanced licensure in cardiovascular technology as well as radiological health.