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Print this pageWashington, DC - February 20, 2009 - Quest Diagnostics recently notified thousands of doctors that some of their patients may have received inaccurate test results from the company. The problem test measures the level of vitamin D in the blood, but the incident illustrates how gaps in the regulatory system for tests – including genetic tests – can wreak havoc on doctors’ abilities to effectively treat their patients.
Studies have connected vitamin D deficiency to conditions ranging from bone weakness to heart attacks, but too-high levels of the vitamin can be toxic. So doctors often have a patient’s blood tested before recommending vitamin supplements. Even before Quest’s high-profile flub, however, some physicians had learned to take vitamin D test results with a grain of salt. The New York Times reports that a few years ago, one doctor “sent a sample of his blood to six laboratories and got results that ranged from 14 nanograms a milliliter, which would be a deficient level, to 41 nanograms — a level three times as high and considered adequate.”
The Times notes that “Quest’s problems with the vitamin D analysis arose after it shifted in 2006 and 2007 to a new test of its own design, replacing an older F.D.A.-approved test.” Laboratory-developed tests (LDTs) like Quest’s are not subject to review by the Food and Drug Administration, as we’ve noted before. The Center for Medicare and Medicaid services, which oversees clinical laboratories, has shown extreme reluctance to implement stricter quality control measures for tests, even in the face of strong evidence that such measures are needed.
The problems in the vitamin D test only came to light because Quest recognized its mistake, notified physicians, and offered to re-test affected patients. While this reflects well on Quest, it is disturbing that federal regulators responsible for protecting the public's health were MIA. It is impossible to know how many similar testing errors occur every day, though there is reason to believe that the number is substantial.
The Center long has argued that the regulatory system for genetic tests needs to be strengthened to avoid errors in potentially life-changing test results, and the vitamin D test shows the very real dangers of failing to act. As we’ve pointed out, tests should be scrutinized based on the level of risk they pose, rather than on who develops the test and how it is performed, as happens currently. Laboratories performing high-risk tests should be required to prove that they consistently report correct results. It’s that simple. – Kathy Hudson and Shawna Williams
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