Quest Diagnostics, Madison, N. J. is involved in a controversy over giving suspicious vitamin D test results.

Quest Diagnostics a lab performing tests has admitted that some of the vitamin D tests it conducted in 2007 and part of 2008 showed incorrect values. Quest's laboratories have branches throughout the country.

The error became evident when physicians had apprehensions regarding the test reports of some patients. It was then that the company started investigating the issue, says Wael Salameh, an endocrinologist and medical director of the endocrine laboratory at Quest Diagnostics' Nichols Institute, in San Juan Capistrano, Calif.

The tests showed readings that were too high. Accordingly some patients who were required to be given vitamin D supplementation did not get it.

On coming to know of the folly, the lab sent letters to the patients and offered for them to be retested. Salameh feels that the lab officials had been very transparent about admitting their mistake. It also shows their concern for the patients who were informed accordingly and asked to get re-tests done.

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