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Vitamin D Deficiency and Thyroid Disease

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Vitamin D is an important vitamin that not only regulates calcium, but also has many other beneficial actions. Not many endocrinologists realize this, but several articles published over 20 years ago showed that patients with hypothyroidism have low levels of vitamin D.

This may lead to some of the bone problems related to hypothyroidism. It was thought that one of two mechanisms may explain the low levels of vitamin D in patients with hypothyroidism, 1) the low levels of vitamin D may be due to poor absorption of vitamin D from the intestine or 2) the body may not activate vitamin D properly. Other articles have demonstrated that patients with Graves disease also have low levels of Vitamin D.

Importantly, both vitamin D and thyroid hormone bind to similar receptors called steroid hormone receptors. A different gene in the Vitamin D receptor was shown to predispose people to autoimmune thyroid disease including Graves’ disease and Hashimoto’s thyroiditis. For these reasons, it is important for patients with thyroid problems to understand how the vitamin D system works.

Sources of Vitamin D

Vitamin D is really two different compounds, ergocalciferol (vitamin D2), found mainly in plants and cholecalciferol (vitamin D3), found mainly in animals. Both of these hormones are collectively referred to as vitamin D, and they can either be obtained in two ways. One is by exposure of the skin to the ultraviolet (UV) rays of sunlight or also from dietary intake.

Vitamin D is found naturally in fish (such as salmon and sardines) and fish oils, eggs and cod liver oil. However most Vitamin D is obtained from foods fortified with Vitamin D, especially milk and orange juice. Interestingly, as breast feeding has become more popular, the incidence of Vitamin D deficiency has increased as less fortified milk is consumed.

Vitamin D deficiency may also occur in patients with malabsorption from their intestine, such as in the autoimmune disease called Celiac Disease, which occurs frequently in patients with thyroid problems. Multivitamins also contain Vitamin D, as does some calcium supplements like Oscal-D and Citracal plus D.

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.

Dr. Friedman usually recommends measuring a 25-OH vitamin D to determine if a patient does have vitamin D deficiency. Occasionally, PTH and calcium, can also be ordered. The 25-OH vitamin D assay has a normal range of approximately 20-60 ng/dL. However, this range may be too low for many patients. In general, Dr. Friedman would recommend treatment of patients that have a 25-OH vitamin D of less than 30 ng/dL. Optimal levels of 25-OH Vitamin D for patients with thyroid diseases are probably 35-60 ng/dL.

Treatment of Vitamin D Deficiency

There are several ways to correct for the depletion of vitamin D, and these would involve either increasing sunlight exposure or increasing dietary intake. In general, Dr. Friedman feels there is an ongoing battle between endocrinologists and dermatologists about sunlight exposure, and mild sunlight exposure probably does not have that much of an increased risk of skin cancer yet would be helpful to prevent vitamin D deficiency. Because of our busy schedule, many of us do not go outside during the day much and our sunlight exposure is minimal. When we do go outside, we are usually covered up with clothes. Blacks and other dark skinned patients absorb less Vitamin D and need more sunlight exposure. Dr. Friedman
recommends a patient to be exposed to the sun for 15-30 minutes a day, especially in the morning, to correct for vitamin D deficiency. However, in northern latitudes, little light of the proper wavelength goes through the atmosphere in the winter, so this exposure needs to occur in the spring and summer at which time stores of vitamin D are built up. The body has mechanisms so that too much vitamin D can not be synthesized by prolonged sun exposure.

An alternative is to go to a tanning salon for approximately three times. When it comes to replacing Vitamin D, again we have to understand the difference between
D2 (ergocalciferol) and D3 (cholecalciferol). Even though both forms of vitamin D are fat soluble, studies have shown that if you take D2, your levels rise, but then fall back to almost baseline in a few weeks. In contrast, after D3, the levels stay high for a longer period of time. Dr. Friedman and other doctors frequently prescribe a high dose (50,000 iu) of vitamin D weekly for 8 weeks, but this is D2 and in many people the levels drop down to normal after nor taking it for a few months. This needs to be given by a prescription. Vitamins and preparations like Oscal D contain D3, however the amount in these preparations are small.
For example, each multivitamin contains 400 international units of vitamin D3 so a total of 800 international units of vitamin D will probably prevent Vitamin D deficiency and may correct very mild cases of low vitamin D levels, but is not enough to correct most cases of vitamin D deficiency. For more severe levels, the patient can take 50,000 international units of vitamin D orally once or twice a week.
Dr. Friedman finally found a product that has high doses of D3 that could be used to rapidly restore vitamin D levels in patients that are deficient and keep the levels up. This product 50,000 iu d3 is sold in bottles of 12 by bio-tech-pharm.com and is catalogue D-3-50. The website is https://secure.bio-techpharm.
com/detail.aspx?product_id=19&cat_id=2&subcat_id=0. You may also order the 100
pill bottle at https://secure.bio-techpharm.
com/detail.aspx?product_id=20&cat_id=2&subcat_id=0 and have enough for
maintenance or share it with your friends.
For a 25-OH vit D levels between 20 and 25, Dr. Friedman recommends taking one pill a week for 8 weeks, then checking a 25-OH vitamin D. If levels are in the normal range, then you can take one pill a month for the next 6-12 months for maintenance. After 6 months, you should be adequately treated. For patients with 25-OH vit D level between 25 and 30, one pill a week for 6 weeks is recommended. For patients with 25-OH vit D level less than 20, it is recommended to see your Endocrinologist to determine proper treatment. If levels are in the normal range, then you can take one pill a month for the next 6-12 months for maintenance.

Please take the pills weekly and not daily.

The main side effect of vitamin D therapy is overtreatment leading to hypercalcemia. Patients with kidney problems cannot convert vitamin D to the active 1, 25-OH vitamin D levels and need to take calcitriol which is 1, 25-OH vitamin D. Additionally, patients with hypoparathyroidism are usually placed on the calcitriol as well.


Vitamin D appears to have many effects besides being related to calcium and bone health. Some patients with low vitamin D levels have fatigue and bone pain, which is easily reversible with proper replacement of vitamin D. Vitamin D may protect against heart disease and some types of cancer. Vitamin D may also have some role in regulating the immune system and also reducing blood sugar levels in patients with diabetes. Proper vitamin D levels are needed to prevent osteoporosis. In conclusion, proper vitamin D levels are essential for one’s health, especially if you have thyroid problems. Unless a patient is exposed to sunlight or foods containing vitamin D, screening for Vitamin D deficiency is recommended for all thyroid patients.

This article is not intended to offer medical advice and is offered for information purposes only. Do not act or rely upon information from this article without seeking professional medical advice. For more information about Dr. Friedman or to schedule an appointment, please go to goodhormonehealth.com

Add a Comment11 Comments

EmpowHER Guest

I know this thread is old but I'm going through a lot of information, I have been testing with low thyroid since my pregnancy with my youngest son now 5 1/2 year's old. Also with a vitamin D deficiency. I have a lot of the "commonly known" issues related to hypo or hyper both. No Doctor can seem to figure what is wrong with me.. I'm exhausted every day all day, I have bad insomnia but even if I get a good night's sleep I sleep during the day. I'm not talking power naps I'm talking 4 hour's at least and still tired. I hardly eat, nauseous a lot. Depression, horrible anxiety, my hair is falling out but not to extreme like photos, I have no sex drive.. I can go on and on, I couldn't bread fed despite my efforts 24 years old 1st child, 32 2nd child. I'm 38 years old now. I still have no answer's. I literally use the phrase I'm sick and tired of being sick and tired but it's a joke to them and very serious to me. I know something isn't right but they can't seem to tell me what. Oh my low thyroid lvls weren't low enough to medicate me or to alarm my doctors, that's what I was told.. vitamin D and B were very low according to my lab work. I'd love any information I can get. Please help me, I'm too young to live like this and have a family to care for. :(

October 18, 2017 - 7:58am
EmpowHER Guest

Vitamin d deficiency had been common in most of the people.. I wish everyone should have some knowledge to over come the problems.

Thanks for sharing

November 4, 2013 - 3:50am
EmpowHER Guest

Other articles have demonstrated that patients with Graves disease also have low levels of Vitamin D.

August 6, 2013 - 11:58pm
EmpowHER Guest

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.

August 3, 2013 - 5:05am

i never knew vitamin d deficiency could cause thyroid problems. what is the best way to treat this? Exposure to sunlight?

August 13, 2010 - 11:05am
EmpowHER Guest

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 cholesterol and all that, but never anyone told her to check her vitamin d level.
SO the lesson here is to have your levels checked by your doctor!

June 15, 2010 - 7:13pm
EmpowHER Guest

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 - 7:33am
EmpowHER Guest

I 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.
What do i do or what r my options? I have an appt with Endo in a month....thanks Ann

April 18, 2009 - 3:34pm
EmpowHER Guest

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 - 9:01am
EmpowHER Guest

I 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 - 7:53am
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We value and respect our HERWriters' experiences, but everyone is different. Many of our writers are speaking from personal experience, and what's worked for them may not work for you. Their articles are not a substitute for medical advice, although we hope you can gain knowledge from their insight.

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