The Nation's Health + [vitamin D]

Dr. Cannell comments on vitamin D lab tests

As always, Dr. John Cannell of The Vitamin D Council continues to teach us new lessons about vitamin D.

Apparently, Dr. Cannell is swamped with the attention that vitamin D is drawing, largely due to his efforts to publicize the enormous deficiency of Americans and his great talent for articulating the science. The most current newsletter, while a bit haphazard, makes some excellent new points that I reprint here.

(I did not reprint his conversation about "any form of vitamin D" being acceptable. My experience differs: In nearly 1000 patients who have taken vitamin D supplements, my experience is that most tablet forms are inconsistently absorbed, sometimes not absorbed at all. I therefore advocate only use of gelcaps or liquids. I'm told by members of Track Your Plaque, however, that they are witnessing reliable increases in blood levels of vitamin D by taking the powdered form of Bio Tech Pharmacal's product.)

Does it matter what reference lab my doctor uses?

Yes, it might make a huge difference. A number of methods exist to measure 25(OH)D in commercial labs. The two most common are mass spectrometry and a chemiluminescence method, LIAISON. The first, mass spectrometry, is highly accurate in the hands of experienced technicians given enough time to do the test properly. However, in the hands of a normally trained technician at a commercial reference lab overwhelmed with 25(OH)D tests, it may give falsely elevated readings, that is, it tells you are OK when in fact you are vitamin D deficient. The second method, chemiluminescence, LIAISON, was recently developed and is the most accurate of the screening, high throughput, methods; LabCorp uses it. Quest Diagnostics reference lab uses mass spec. Again, both Quest and LabCorp are overwhelmed by 25(OH)D requests. The problem is that the faster the technicians do the mass spec test, the more inaccurate it is likely to be. If your 25(OH)D blood test says "Quest Diagnostics" on the top, do not believe you have an adequate level (> 50 ng/ml). You may or may not; the test may be falsely elevated. Let me give you an example. A doctor at my hospital had Quest Diagnostics do a 25(OH)D. It came back as 99 ng/ml of ergocalciferol. He is not taking ergocalciferol (D2), he has never taken ergocalciferol, only cholecalciferol, and he is not taking enough to get a level of 99 ng/ml, 50 ng/ml at the most. His email to Dr. Brett Holmquist at Quest about why Quest identified a substance he was not taking went unanswered other than to say "any friend of Dr. Cannell's is a friend of ours."

Long story short: if your lab report says "LabCorp" on the top, it is probably accurate; if it says Quest Diagnostic, it may be falsely elevated. While LabCorp has also been overwhelmed with 25(OH)D requests, the LIAISON method they use is relatively easy to do and does not rely on technician skill as much as the mass spec methods do. I'm not saying this because I'm a consultant for DiaSorin, who makes LIAISON, I'm saying it because it is true. If you don't believe me, get Quest to make me an offer to be their consultant at 10 times what DiaSorin is supposed to be paying me ($10,000 per year) and see how fast I turn Quest down. If Quest fixes their test, I'd love to consult. The ironic thing: I've made both Quest and LabCorp lots of money via this newsletter, the website, and by repeatedly telling the press that people need to know their 25(OH)D level, which has contributed to the skyrocketing sales of 25(OH)D blood tests.

Demand for vitamin D tests soars as nutrient's potential benefits touted.

Here you can help. Find out which labs in your town use Quest Diagnostics and which use LabCorp. Have a 25(OH)D test at both labs the same day (you will have to pay for them yourself). Then send both results to the Vitamin D Council address below. If Quest Diagnostics does not fix their 25(OH)D test, the Vitamin D Council will fix it for them.

My doctor prescribed Drisdol, 50,000 IU per week. What is it?

Drisdol is a prescription of 50,000 IU tablets of ergocalciferol or D2. Ergocalciferol is not vitamin D but it is similar. It is made by irradiating ergosterol, which is found in many living things, such as yeast. D2 is not normally found in humans and most studies show it does not raise 25(OH)D levels as well as human vitamin D (cholecalciferol or D3) does. However, Drisdol is a lot better than nothing. The best thing to do, if you are vitamin D deficient, and a human, is to take human vitamin D, cholecalciferol, A.K.A. vitamin D3.

What is the ideal level of 25(OH)D?

We don't know. However, thanks to Bruce Hollis, Robert Heaney, Neil Binkley, and others, we now know the minimal acceptable level. It is 50 ng/ml. In a recent study, Heaney et al enlarged on Bruce Hollis's seminal work by analyzing five studies in which both the parent compound, cholecalciferol, and 25(OH)D levels were measured. It turn out that the body does not reliably begin storing the parent compound (cholecalciferol) in fat and muscle tissue until 25(OH)D levels get above 50 ng/ml. The average person starts to store cholecalciferol at 40 ng/ml, but at 50 ng/ml, virtually everyone begins to store it for future use. That is, at levels below 50 ng/ml, the body is usually using up the vitamin D as fast as you make it or take it, indicating chronic substrate starvation, not a good thing.

Hollis BW, Wagner CL, Drezner MK, Binkley NC. Circulating vitamin D3 and 25-hydroxyvitamin D in humans: An important tool to define adequate nutritional vitamin D status. J Steroid Biochem Mol Biol. 2007 Mar;103(3-5):631-4.

Heaney RP, Armas LA, Shary JR, Bell NH, Binkley N, Hollis BW. 25-Hydroxylation of vitamin D3: relation to circulating vitamin D3 under various input conditions. Am J Clin Nutr. 2008 Jun;87(6):1738-42.

I have advanced renal failure and I'm on dialysis, how much vitamin D should I take?

The same as everyone else. Since I have told you about commercial labs ripping you off, let's add some drug companies. Patients with advanced renal failure need activated vitamin D or one of it's analogs, available by prescription. This is very important as their kidneys cannot make enough 1,25-dihydroxy-vitamin D (calcitriol) to maintain serum calcium. However, the rest of their tissues activate vitamin D just fine and when those tissues get enough, and when the kidneys get more vitamin D, the calcitriol spills out into the blood, lowering their need for prescription calcitriol or one of its analogs. The companies that make the analogs don't like that, it means reduced sales. So these companies do nothing, the scientists behind these companies say nothing, and renal failure patients die prematurely from one of the vitamin D deficiency diseases.

Vieth R. Vitamin D toxicity, policy, and science. J Bone Miner Res. 2007 Dec;22 Suppl 2:V64-8.

When I asked my doctor for a 25(OH)D blood test, he just laughed and said it was all idiotic. What can I do?

Help me unleash the dogs of war, the plaintiff attorneys. If you read about past nutritional epidemics caused by society, such as beriberi or pellagra, you will realize that education alone will take decades. Physicians successfully fought against the idea that thiamine deficiency caused beriberi for decades. However, things are different now. The agents of change in modern America, as obnoxious as they are, are plaintiff attorneys. Once the first malpractice lawsuits claiming undiagnosed and untreated vitamin D deficiency led to breast cancer, autism, heart disease, etc., get past summary judgment, and they will, and end up in front of a jury, and they will, things will change rapidly. One of the main reason physicians do what they do is fear of lawsuits. In a matter of months, arrogance and ignorance will give way to 25(OH)D tests and vitamin D supplementation.

Goodwin JS, Tangum MR. Battling quackery: attitudes about micronutrient supplements in American academic medicine. Arch Intern Med. 1998 Nov 9;158(20):2187-91.

And, to help support Dr. Cannell's efforts (I sent him a check for $250 a few months back; time for more), here is his contact info:

John Cannell, MD
The Vitamin D Council

Send your tax-deductible contributions to:

The Vitamin D Council
9100 San Gregorio Road
Atascadero, CA 93422