Hello Monica,

You have done well to persuade the lab to do testing directly for you, when the doctor is not interested.

Firstly, you asked about diagnosis:

The apparent contradiction in your results is caused by differences in half-life between the two forms of vitamin D. Here are extracts from what one expert, Andrew M Wootton, says about this:

You can read the entire article by following this link:

Improving the Measurement of 25-hydroxyvitamin D, Andrew M Wootton, Clin Biochem Rev. 2005 February; 26(1): 33–36

Your "Vit D 25 Hydroxy" (25OHD) result represents your long-term vitamin D storage, and is the most reliable indicator of your vitamin D status. With a relatively long half-life of several weeks, it is not significantly affected by short-term changes in your sun exposure.

Your "Vit D 1,25 Dihydroxy" (1,25(OH)2D) result is affected by short-term changes in your sun exposure, because it has a half-life of only a few hours, and does not represent your long-term vitamin D storage.

So, do you have a vitamin D deficiency? Unfortunately, because your 25OHD result is borderline low, the answer is not entirely clear. The reference values given by your lab are consistent with those of Mayo Medical Labs:

Mayo Medical Laboratories Test Catalog 25-Hydroxyvitamin D2 and D3, S

My rheumatologist diagnosed me with vitamin D deficiency last September, when my 25OHD result was also borderline low at 55 pmol/L (= 22 ng/mL). He warned me that this subject is a "can of worms" (just as is my main interest of vitamin B12 deficiency).

Some of the problems with diagnosis of vitamin D deficiency include:

• Disagreement about optimum level
• Inconsistencies between labs
• Some assays understate level of D2

Here is what one team of researchers, led by N. Binkley, concluded:

Here is a link to the article:

Assay Variation Confounds the Diagnosis of Hypovitaminosis D: A Call for Standardization, N. Binkley et al, The Journal of Clinical Endocrinology & Metabolism Vol. 89, No. 7 3152-3157

Here are links to more articles on vitamin D deficiency:

Vitamin D Deficiency: What a Pain It Is, Michael F. Holick, Mayo Clin Proc. 2003;78:1457-1459

Prevalence of severe hypovitaminosis D in patients with persistent, nonspecific musculoskeletal pain, Plotnikoff GA et al, Mayo Clin Proc. 2003;78:1463-1470

High Prevalence of Vitamin D Inadequacy and Implications for Health, Michael F. Holick, Mayo Clin Proc. 2006;81(3):353-373

Contemporary Diagnosis and Treatment of Vitamin D-Related Disorders, The American Society for Bone and Mineral Research
Contains several audio-visual presentations

Vitamin D Council
Contains links to several articles.

The Uncensored Family Guide to Vitamin D, Bill Sardi

Health Research Forum
Contains links to several articles.

Vitamin D intake and vitamin D status of Australians, Caryl A Nowson and Claire Margerison, MJA 2002 177 (3) : 149-152

Now, for your second question:

If you accept the Mayo reference values given above, you would be mildly vitamin D deficient. According to N. Binkley, cited above:

I was in a very similar situation to where you are now, with a borderline-low vitamin D result. I also was first tested at the end of our winter, just as you have been, so the level is likely to be at its lowest if you rely on sun exposure.

Rather than immediately commence taking supplements, I decided to try for careful sun exposure. Remember that once you rely on supplements, for any nutritional deficiency, you are stuck with them for life. That is why I urge people to always test first, then commence treatment if necessary.

I decided to have my vitamin D level re-tested on a new sample, just a few weeks after the first test, before I started serious sun exposure. The level increased from 55 pmol/L (22 ng/ml) to 100 pmol/L (41 ng/ml), before I had even started to try to increase the level! Perhaps the small increase in incidental exposure was sufficient to have some effect, but this would be inconsistent with the findings of Andrew M Wootton, cited above, that 25OHD represents long-term vitamin D status.

Regardless of this result, I commenced half-hour walks each day, when there was sufficient UV to be useful for vitamin D production, but not so much that it would cause sunburn. My 25OHD levels have been within the range 85 to 100 pmol/L (35 to 41 ng/ml) since last September, despite periods of up to five weeks with very little sun during our Summer. (We had a very cloudy and rainy summer).

I suggest that, rather than immediately starting on a vitamin D supplement, you could increase your safe sun exposure for at least four weeks, then have your level tested again. If your vitamin D level increases to more than 32 ng/ml, you can continue to occasionally monitor your levels. If you can maintain at least the 32 ng/ml even during your Winter, then you should not need vitamin D supplements. You might choose to use supplements, but only when you cannot get sufficient sun exposure.

You do need to be very careful to avoid sunburn, as this will increase risk of skin cancer. I live in the melanoma capital of the world, in Queensland, where we are very aware of the problem.

I suggest that you try to obtain local information about UV levels, so that you can plan when to safely have your sun exposure. In Australia, this information is provided as part of our weather forecast by the Bureau of meteorology. For example, here is a link to today's UV index forecast for where I live:

http://www.bom.gov.au/products/UV/Su...oast_QLD.shtml

There is also a "live" UV index service provided by QUT:

http://www.uv.hlth.qut.edu.au/community/uvindex.jsp

Here are links to other UV index sites:

World Health Organization UV index reporting sites
(the link to the Mexico City site was broken when I tried it today)

U.S. Environmental Protection Agency Sunwise Program
This site not found in WHO list

NOAA/ National Weather Service Climate Prediction Center
Links to International UV index sites

Global Solar UV Index - A Practical Guide
Detailed information about UV index

University of Colorado
Links to International UV index sites

Tropospheric Emission Monitoring Internet Service UV index forecast and archives
Daily updated colour maps of Europe and world UV index

The Ozone Hole
Links to International UV index sites

Here are links to some articles for vitamin D, sun exposure and UV:

Ultraviolet radiation and health: friend and foe, Robyn M Lucas and Anne-Louise Ponsonby, MJA 2002 177 (11/12): 594-598

Risks and benefits of sun exposure, The Cancer Council Australia

A little ray of sunshine - but not too much - important for health, The Cancer Council Australia

Estimates of beneficial and harmful sun exposure times during the year for major Australian population centres, Amanda J Samanek et al, MJA 2006; 184 (7): 338-341

Vitamin D and adult bone health in Australia and New Zealand: a position statement, Working Group of the Australian and New Zealand Bone and Mineral Society, Endocrine Society of Australia and Osteoporosis Australia*, MJA 2005; 182 (6):281-285

Sun protection messages, vitamin D and skin cancer: out of the frying pan and into the fire?, Monika Janda et al, MJA 2007; 186 (2): 52-53

Vitamin D in Australia. Issues and recommendations. Caryl A Nowson et al, Australian Family Physician, Vol 33, No. 3 (97-192)

The UV Advantage

Please let us know what you decide to do, and the results.

Paul