Different Forms of Vitamin D and How To Diagnose Vitamin D
Vitamin D itself is inactive and needs to get converted to the liver to 25-hydroxy vitamin D (25-OH vitamin D) and then in the kidney to 1, 25-hydroxy vitamin D. It is only the 1, 25- OH vitamin D which is biologically active. This form of vitamin D acts to allow for absorption of calcium from the intestinal tract. Therefore, patients with low vitamin D levels will have low calcium and in severe cases get rickets (in children) or osteomalacia (in adults) which is when the bone bows out and is poorly formed. In mild cases of vitamin D deficiency, osteoporosis occurs, but low calcium is rare.
The conversion from the 25-OH vitamin D to the 1, 25-OH vitamin D that occurs in the kidney is catalyzed by parathyroid hormone, also called PTH. Therefore, patients with very low vitamin D levels will have relatively high PTH levels often with low calcium levels.
This is similar to patients with primary hypothyroidism having elevated TSH levels while having normal thyroid hormone levels. Additionally, the 25-OH vitamin D form which is the storage form and is much more abundant that the 1, 25-OH vitamin D form which, although is active, is less abundant. Therefore, in states of vitamin D deficiency, low levels of 25-OH vitamin D are found, but the 1, 25-OH vitamin D levels are either normal or actually slightly high. They are slightly high because the excess PTH that is stimulated by the low 25-OH vitamin D levels stimulates the conversion up to 25-OH vitamin D to the 1, 25-OH vitamin D. Thus, patients that are vitamin D deficient usually have a low 25-OH vitamin D level, a high PTH level, a low normal calcium, and a normal or an elevated 1, 25- OH vitamin D level. However some patients may actually have a high normal calcium as
the elevated PTH and 1, 25-OH vitamin D may cause increased calcium absorption from the GI track and reabsorption from the kidney. If 25-OH vitamin D levels were not measured, these patients might have been incorrectly diagnosed with mild hyperparathyroidism as they have a high normal calcium and a high PTH.
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i never knew vitamin d deficiency could cause thyroid problems. what is the best way to treat this? Exposure to sunlight?
August 13, 2010 - 11:05amThis Comment
Well, to make the long story short, my friend had thyroid problems. Later they found out he has some nodules in her thyroid too. After that he was diagnosed with Vitamin D Deficiency. She had never heard of such thing. It's always about checking her cholesteral and all that, but never anyone told her to check her vitamin d level.
June 15, 2010 - 7:13pmSO the lesson here is to have your levels checked by your doctor!
There is a mistake in your article.
Dr., You've mixed up your Vit. D types. In the article you say, " cholecalciferol (vitamin D2) and ergocalciferol (vitamin D3)." You have it reversed. Actually, Vit. D3 is cholecalciferol and Vit. D2 is ergocalciferol.
If you need extra proof, just check out the National Osteoporosis Foundation's website at http://www.nof.org/prevention/vitaminD.htm
June 25, 2009 - 7:33amI am a gastric bypass patient of 5 years. My vitamin D -25 hydroxy levels was a 5. My question is if I can not absorb the 50,0000 IU am i just taking pils? I am in alot of pain and aches with my joints and hand and leg pain and have family history of arthritis, and cushing syndrom and ankloysis.
April 18, 2009 - 3:34pmWhat do i do or what r my options? I have an appt with Endo in a month....thanks Ann
Mothers that are breast feeding and are worried about the lose of D-3. Just get the baby out in the sun when possible.............Pete
March 29, 2009 - 9:01amI understand the concern that vitamin D deficiency in infants may increase with breast feeding may be misconstrued as advice against breast feeding babies. What I think the point here is that if a mother is breast feeding, she should also give her child a vitamin D supplement in addition to breast milk rather than forgo breast feeding the baby.
It amazes me that the importance of vitamin D has been so ignored. I have just been floored by the articles that have been coming out the last two years relating low vitamin D to everything from diabetes to MS to obesity to stroke to heart disease to back pain to cancer. Now thyroid disease too. How much money could we save on medical treatment and improve our quality of life just by taking a cheap vitamin D supplement? I started.
March 29, 2009 - 7:53amDear Dr Friedman,
Thank you for your article however there is one point which I disagree with.
Your inference that vitamin D could relate to increased breast feeding is I think and bad inference to make to mothers. There are so many benefits from breast feeding and so many negatives attached to formula that you just have to look at the third world (yes even if we have better water although that could be debated). What you will find is a bigger correlation between vitamin D deficiency and the use of sun block (particularly on children) and the common vitamin D deficiency past on from parent to child. Pre conception health of both parents is key.
March 28, 2009 - 8:01am