Vit D Deficiency: Medical Problem Or Medical Testing Errors?

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Quest Acknowledges Errors in Vitamin D Tests

January 8, 2009

By ANDREW POLLACK

The nation’s largest medical laboratory company provided possibly

erroneous results to thousands of people who had their vitamin D levels

tested in the last two years, the company has acknowledged.

The company, Quest Diagnostics, has already sent letters to thousands of

doctors listing the patients who might have received “questionable” test

results and is offering free retests. The company said it had fixed the

problems.

An erroneously high result may mean patients will not take vitamin D

supplements when perhaps they should, doctors said. And an erroneously

low test result might lead in rare instances to a toxic overdose of

vitamin D. When the Quest tests have been inaccurate, the reading has

typically been too high, although not in all cases.

Quest’s action represents “the largest patient test recall I’m aware of

in my 20 years in the business,” said L. Michel, editor of The

Dark Report, a newsletter for pathologists that first reported on

Quest’s action.

The incident could raise calls for more regulation of diagnostic testing

at a time when diagnostics are playing an increasingly crucial role in

guiding medical treatment. Many laboratory tests, including Quest’s

vitamin D test, do not require approval from the Food and Drug

Administration.

The incident also raises questions about vitamin D testing, which has

surged because studies have suggested that a deficiency of the nutrient

raises the risk of bone weakness, cancer, heart attacks, autoimmune

diseases and other illnesses. Quest and other laboratories have reported

that in some cases test volumes had nearly doubled from one year to the

next. Medicare pays about $40 for a vitamin D test, though doctors say

some of their patients were billed as much as $200 for the Quest test.

But experts say that so far there is no standardization of the tests,

meaning that results can differ considerably from one laboratory to another.

That can make it hard for doctors to decide on treatment and for experts

to compare studies aimed at determining the optimal level of vitamin D

in the blood. “If you get your vitamin D level measured in the Mayo

Clinic, the Cleveland Clinic and the Timbuktu Clinic, it would be nice

if it came out the same value,” said Dr. Neil C. Binkley, associate

professor of medicine at the University of Wisconsin.

Dr. Binkley said that a few years ago he 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. While the tests’

consistency has improved since then, there can still be substantial

variability, he said.

Yet many experts say that even if the tests were accurate, there would

still be uncertainty in how to treat patients. There is considerable

debate about how much vitamin D is needed and whether vitamin D

supplements even prevent various diseases. Vitamin D is usually made by

the body when the skin is exposed to sunlight and is also contained in

oily fish and some fortified drinks like milk.

Some doctors said they had switched to other testing laboratories

because of Quest’s problems. But Quest, based in Madison, N.J., offers

numerous tests, from routine blood work to sophisticated genetic tests.

No one type of test represents a large potion of its revenue, which was

$5.45 billion for the first nine months of 2008.

The company said the retesting would not have a material effect on its

earnings. The company’s stock price rose 80 cents Wednesday to $49.20,

approximately in the middle of its 52-week range.

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. The new test promised to be more accurate and

offer more detailed information, Quest executives said. But the test

relied on a sophisticated instrument called a mass spectrometer, which

can be tricky to use, especially for high-volume testing.

Dr. Wael A. Salameh, the medical director for endocrinology at Quest’s

most sophisticated laboratory, which is in San Capistrano, Calif.,

said some materials used to calibrate test results had been faulty. And

four of the seven Quest testing laboratories around the country did not

always follow proper procedures, he said.

Quest would not say how many patients were affected. But a spokesman did

not deny that thousands of doctors were sent letters in October. Each

doctor had at least one patient, and in many cases dozens of patients,

who had a possibly inaccurate test result.

Dr. Salameh said the inaccurate results represented less than 10 percent

of all the vitamin D tests done by Quest from early 2007 to mid-2008.

And even many of the possibly inaccurate results were probably accurate,

he said, because Quest sent letters even if there was only a remote

chance that the test was erroneous.

“We are kind of being penalized for going the extra mile,” he said.

Dr. L. Hoffman, a clinical nutritionist in New York City, said

his letter from Quest mentioned about two dozen of his patients. “There

was a patient we put on vitamin D and all of a sudden, for the first

time ever, the patient came back with what seemed to be a toxic level of

vitamin D,” said Dr. Hoffman, who is also host of a radio program on

health, on WOR in New York City. When the patient was given a different

vitamin D test, the value was considerably lower.

Dr. Lawrence D. Rosen, a pediatrician in Oradell, N.J., who treats many

autistic children, said his letter named more than 20 patients and that

retesting was an inconvenience. “A lot of these kids, especially if

they’re autistic, it’s a big deal for parents to have their blood

drawn,” he said.

One question is why Quest’s problems took so long to discover. Some

doctors who advocate vitamin D use said they had begun noticing some

unusually high test results in 2007 and had begun complaining publicly

in the summer of 2008.

One of them was Dr. J. Cannell, a psychiatrist at a California

hospital for the criminally insane who started the Vitamin D Council to

promote use of the vitamin. He said that after the test was introduced,

he started noticing that some patients had normal levels of vitamin D, a

departure from the past, when the levels had often been low.

“A black man coming from solitary confinement on C.D.C.R. food cannot

have a normal level of vitamin D,” he said, referring to the California

Department of Corrections and Rehabilitation. People with dark skin do

not convert sunlight to vitamin D as easily as those with lighter skin.

Quest executives say they dismissed the concerns of Dr. Cannell because

he was a paid consultant to DiaSorin, a company that makes a rival test.

They said the company’s review of its testing results had instead

been prompted mainly by its own review of national health trends based

on Quest data, which had shown an unusual rise in average vitamin D

levels.

Meanwhile, the F.D.A. is considering increasing its role in regulating

diagnostic tests. Now, test kits sold to labs, hospitals and doctor’s

offices must be approved by the agency. But tests developed and offered

by a single laboratory, like the Quest vitamin D test, do not.

Quest and many other laboratories argue that lab quality is already

regulated through Medicare and that having to win approval for each new

test will slow innovation and raise costs.

Copyright 2009 The New York Times Company