Data presented this week at the American Association for Clinical Chemistry (AACC) meeting shows that many people have low vitamin D levels and that testing individuals at risk may be beneficial.
According to published data from the Third National Health and Nutrition Survey, reported in the Archives of Internal Medicine, only 23 percent of Americans have vitamin D levels greater than 30 nanogram/millilitre (ng/mL), a level that many experts agree is needed for optimal health. [Editor’s Note: Other experts recommend even higher levels.] Low vitamin D can cause skeletal disorders, such as rickets in children and bone loss in adults, and has been linked to an increased risk of hip fractures. Although research is still being conducted in this area, some studies have shown that people with a low level of vitamin D may have elevated risk for cardiovascular problems, autoimmune disorders and some infectious diseases.
"There are many factors that contribute to people having low vitamin D status," says Neil Binkley, M.D., associate professor of Endocrinology and Geriatrics at University of Wisconsin School of Medicine and Public Health. "Low dietary intake, sun avoidance, age and geographic location all play a part. It is important to measure vitamin D in some individuals who may be at risk because of all of variables that may cause low vitamin D." Binkley presented data at an AACC workshop.
Laboratories measure vitamin D levels through detection of 25-hydroxy vitamin D. In the kidney, 25-hydroxy vitamin D converts into the active form of the vitamin that helps regulate calcium and phosphate levels and can be measured in blood. 25-hydroxy vitamin D is established as the appropriate measurable indicator of vitamin D status because it is stable and easily measured.
Several published studies have shown low vitamin D levels are widespread, but the potential health consequences are largely unrecognized. It has been reported in healthy children, young adults, especially African-Americans and middle-aged and elderly adults. Low vitamin D is often present in adults above the age of 50. One study in an outpatient setting showed that 41 percent of otherwise healthy adults 49–83 years were found to have low vitamin D throughout the year.
Additional data presented in a poster session at AACC suggests the automated ARCHITECT® 25-OH Vitamin D assay, when compared with mass spectrometry on 107 patient samples, was highly sensitive and showed good correlation with LC-MS/MS (liquid chromatography tandem mass spectrometry), a laboratory technique used in analytical chemistry.
Abbott (NYSE: ABT) recently filed a submission for clearance to the U.S. Food and Drug Administration (FDA) for a fully-automated vitamin D assay performed on its widely used ARCHITECT testing system. It is currently under FDA review. The ARCHITECT 25-OH Vitamin D assay is approved for use outside of the United States.
About Vitamin D
The general term vitamin D refers to different forms of the vitamin. Vitamin D2 is synthesized by plants and Vitamin D3 is formed when skin is exposed to and absorbs sunlight. Vitamin D promotes calcium and phosphorus absorption to maintain healthy bones. In addition to UV exposure, common sources include fish, beef liver, eggs, cheese and milk.
