Vitamin D - get an accurate test of blood levels of Vitamin D

Quest Diagnostics erroneously reported Vitamin D tests.

Yesterday newspapers all over the USA had this kind of headline.


The story behind the story started 2 years ago when Dr Cannell, working at California's prison for the criminally insane, noticed that Quest Diagnostics blood tests for Vitamin D almost always reported OK levels of Vitamin D. Dr Cannell was amazed “A black man coming from solitary confinement on California Department of Correction and Rehabilitation food cannot have a normal level of vitamin D.” This quote is from the extensive New York times report which had several more amazing quotes.

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.


Quest were hit by a combination of bad luck and some incompetence. The bad luck was that Quest did upgrade their test technology using new equipment but then didn't calibrate the new equipment adequately at all their test labs. Dr. Wael A. Salameh, the medical director for endocrinology at Quest 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.

The big problem is that for 2 years many patients have had Vitamin D test results back from Quest saying they are fine right when it has become plain that Vitamin D intake needs to go up very substantially. Read this editorial on the urgent need to revise up Vitamin D recommendations.


The same editorial has this paragraph: "Evaluation of most relations of health and disease that involve vitamin D leads to the conclusion that a desirable 25(OH)D concentration is 75 nmol/L (30 ng/mL) (3-5). If a concentration of 75 nmol/L is the goal to be achieved by consumption of vitamin D, then why is it so rare for members of the population to accomplish this?


One reason is that almost every time the public media report that vitamin D nutrition status is too low, or that higher vitamin D intakes may improve measures of health, the advice that accompanies the report is outdated and thus misleading. Media reports to the public are typically accompanied by a paragraph that approximates the following: "Current recommendations from the Institute of Medicine call for 200 IU/d from birth through age 50 y, 400 IU for those aged 51–70 y, and 600 IU for those aged >70 y. Some experts say that optimal amounts are closer to 1000 IU daily. Until more is known, it is wise not to overdo it." The only conclusion that the public can draw from this is to do nothing different from what they have done in the past. "


How much Vitamin D ?

The bottom line on Vitamin D ? A meta-analysis of primary prevention high-quality trials published in 2005 found that oral cholecalciferol (D3) in a daily dose of 700–800 IU or intermittently 100,000 IU every 4 months with or without calcium, should reduce both hip and non-vertebral fracture risk significantly compared to placebo. Trials that administered 400 IU vitamin D did not achieve fracture efficacy. Notably, there was a significant association between higher achieved 25-hydroxyvitamin D levels (25(OH)D) in the treatment groups and fracture efficacy: The minimal mean level where fracture efficacy was observed was 74 nmol/l (25(OH)D).

If you have the time read this serious piece on Vitamin D and how much makes a difference.

Which leaves the question "Am I Vitamin d deficient ?" Lab tests via your doctor could still give a wrong answer. Once option is to go direct to get a test for Vitamin D level in the blood. You put a spot of blood on a testing sample and ZRT run a test for you. Dr Cannell, the doctor at the California prison for the criminally insane mentioned earlier, says that he thinks it's accurate.

If you have half an hour look and listen to this Stanford Lecture on Vitamin D.