Re: VIT D testing

[Guest guest]

The correct test is 25(OH)D, also called 25-hydroxyvitamin D

Please note the difference between normal and optimal. You don't want to be

average here; you want to be optimally healthy.

Primitive man likely developed in tropical and sub-tropical conditions with

large exposure to UV-B and its secondary consequence to skin exposure, vitamin

D.

Primitive environmental availability of a nutrient does not necessarily

establish the higher requirements, but these exposures would have influenced the

evolution of the relevant physiology, and such concentrations should at least be

considered presumptively acceptable.

Some experts may disagree with the following healthy ranges, but they are taken

from healthy people in tropical or subtropical parts of the world, where they

are receiving healthy sun exposures. It seems more than reasonable to assume

that these values are in fact reflective of an optimal human requirement.

(Holick MF. Calcium and Vitamin D. Diagnostics and Therapeutics. Clin Lab Med.

2000 Sep;20(3):569-90)

OPTIMAL

25-Hydroxyvitamin D Values

50-70 ng/ml or

115-128 nmol/l NORMAL

25-Hydroxyvitamin D lab Values

20-56 ng/ml

50-140 nmol/l

Your vitamin D level should NEVER be below 32 ng/ml.

Any levels below 20 ng/ml are considered serious defiency states and will

increase your risk of breast and prostate cancer and autoimmune diseases like MS

and rheumatoid arthritis.

If you have the above test performed, please recognize that many commercial labs

are using the older, dated reference ranges. The above values are the most

recent ones based on large-scale clinical research findings.

Make Sure Your Lab Uses the Correct Assay

There are a number of different companies that have FDA approval to perform

vitamin D testing, but the gold standard is DiaSorin. Their radioimmunoassay

(RIA) method for measuring total vitamin D levels has become the gold standard,

not because it's more accurate than the others, but because it's the one used in

almost every major vitamin D study, on which the recommended blood levels for

clinical efficacy are based.

Therefore, in order for any other testing method to offer clinically relevant

results, the test values must agree with DiaSorin RIA results, since those were

used to establish the recommended levels.

Vitamin D status is measured by looking at blood levels of 25-hydroxyvitamin D3.

There are three common methods used for measuring vitamin D3:

1. LC-MS/MS This test measures 25-hydroxyvitamin D2 and D3 separately

2. RIA (DiaSorin) -- Developed in 1985, it accurately measures total

25-hydroxyvitamin D (It does not separate D2 and D3)

3. Liaison (DiaSorin)-- a more recently developed automated immunoassay by

DiaSorin that has largely replaced the RIA

The LC-MS/MS (liquid chromotatography-mass spectrometry) method is the preferred

method for many labs, including the Mayo Clinic, Esoterix, ZRT, and others,

while Liaison is favored by other testing labs like LabCorp.

Recent developments in 2008 have made it clear that there are irregularities in

the values obtained from the different testing methods. Although results from

any of the three assays may be analytically accurate, they might not be

clinically accurate, which is, ultimately, what matters.

Since the DiaSorin assay (RIA) was used in the major clinical studies that led

to the recommended vitamin D levels, any lab using the LC-MS/MS method need to

make sure their test correlate with the RIA test values in order to accurately

determine your vitamin D status.

It's imperative that you find out if your lab has performed the appropriate

recalibrations against DiaSoria's assays. Otherwise your vitamin D levels may be

vastly overstated, in some cases by as much as 40 percent, meaning you may get

the green light that your levels are fine, when in fact you are deficient, or

perhaps even dangerously low.

 

Vic

________________________________

From: nili gitig <ngitig@...>

Sent: Mon, March 14, 2011

 

Several people have posted a specific lab that one should use when testing

Vitamin D levels. I am not sure I remember correctly. Was it LabCorp? I

would appreciate confirmation or correction.

Thanks

Nili

[Guest guest]

Hi Vic,

About how much is the Vit D 25-hydroxy test?

Thanks, Barbara

[Guest guest]

I pay about $40 to $50 from Lab Corp.   

________________________________

From: BW <westwood@...>

Sent: Thu, March 17, 2011 9:05:54 AM

Subject: [ ] Re: VIT D testing

 

Hi Vic,

About how much is the Vit D 25-hydroxy test?

Thanks, Barbara

[Guest guest]

My doctor ordered the test so my insurance paid for it at Quest. I think it

cost me $15.

ar

[Guest guest]

I routinely ask my patients to ask their GP to give them a vit D 25 OH test.

Hardly any of my patients have their D level within the range.

This is despite the fact that Israel has plenty of sunshine.

Gubi

[ ] Re: VIT D testing

My doctor ordered the test so my insurance paid for it at Quest. I think it

cost me $15.

ar