June 26, 2012

Inaccurate Vitamin D Tests Could Cause Misdiagnosis

(Ivanhoe Newswire) —Blood tests that measure Vitamin D deficiency are among the most frequently ordered tests in medicine. A new study found that some test kits are inaccurate.

Researchers at Loyola University Chicago Stritch School of Medicine found that two new tests, Abbot Architect and Siemans Centaur2, may not be accurate. This study was performed on 163 randomly selected blood samples. In 40% of the Abbott Architect specimens and 48% of the Siemans Centaur2 specimens, results were at least 25% too high or 25% too low. The maximum recommended total allowable error is plus-or-minus 25%.

“There has been an exponential increase in the number of vitamin D tests ordered for patients. But our study of two newly approved tests showed they had pretty poor performance." Earle W. Holmes, PhD was quoted saying.

The study by Holmes and colleagues included 163 specimens, 123 from women and 40 from men. Researchers used the two new test kits on the specimens, and compared results with findings from a gold standard method called LCMS(liquid chromatography/tandem mass spectrometry), which has been shown to provide accurate vitamin D measurements.

The new tests tended to overestimate vitamin D deficiency. According to the LCMS measurements, 33 of the 163 specimens showed vitamin D deficiency. But the Abbott test showed that 45 specimens had vitamin D deficiency and the Siemens test showed that 71 subjects had vitamin D deficiency. Such inaccuracies could lead to overtreatment of vitamin D deficiency.

Inaccurate test results could lead to misdiagnoses of patients and confound efforts of physicians, nutritionists and researchers to identify the optimal levels of vitamin D for good health.

Source: ENDO 2012–94th Annual Meeting and Expo, June 2012