Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Font Size

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.

Vitamins and
Lifestyle Guide

Which Nutrients
Are You Missing?

Learn More

Today on WebMD

vitamin rich groceries
Do you know your vitamin ABCs?
St Johns wart
Ease hot flashes and other symptoms.
Are you getting enough?
Take your medication
Wonder pill or overkill?
fruits and vegetables
Woman sleeping
Woman staring into space with coffee

Send yourself a link to download the app.

Loading ...

Please wait...

This feature is temporarily unavailable. Please try again later.


Now check your email account on your mobile phone to download your new app.