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Flawed Results on Some Vitamin D Tests

Quest Diagnostics Notifies Doctors of Patients With Suspicious Results on Vitamin D Blood Tests
WebMD Health News
Reviewed by Louise Chang, MD

Jan. 8, 2009 -- Quest Diagnostics, a company that performs lab tests for patients nationwide, says some of the vitamin D tests it conducted in 2007 and part of 2008 yielded incorrect results.

Quest Diagnostics has already sent letters to the doctors of the patients with suspicious results on their vitamin D test, according to Waeh Salameh, MD, FACS, medical director of the endocrinology lab at Quest Diagnostics Nichols Institute in San Juan Capistrano, Calif.

The letter included a list of the patients who were affected and offered for them to be retested, Salameh tells WebMD.

Patients who were contacted by their doctors to get retested "should follow their doctors' advice and get retested," Salameh says.

The incorrect vitamin D tests tended to overestimate patients' blood levels of vitamin D. Salameh says the errors stemmed from problems with the test's reagents and calibrators, and there were also "issues with some sites not following proper operating procedure."

Those problems have been fixed, Salameh says.

Salameh says he expects that in most cases, the retests "are going to be essentially unchanged" from the first test because Quest broadly defined suspicious results. Only "a few" patients will need a change in their vitamin D therapy because of the incorrect test results, Salameh predicts.

Salameh declined to say how many patients were on the list of people who were offered retesting. And he notes that retesting isn't mandatory; it's up to the doctors' judgment. Media reports refer to "thousands" of patients who may have been affected.

"We think that we went way above industry standards to make sure that all the results [that] were incorrect are corrected. The magnitude of what we have done reflects our transparency and concern for the patients," Salameh says.

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