Calcium Supplements and Thyroid Hormone Replacement

A Reader's Personal Experience

Man holding pills and glass of milk, close-up
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Here's a letter I received from a reader, with an important personal message that is worth sharing with other thyroid patients and family members. 

Dear Mary,

Last year my mother was diagnosed with hypothyroidism. Our doctor put her on the smallest dose of Synthroid for two weeks, after which she was supposed to return for a blood test. The blood test showed that there was no improvement but, because my mom had not taken the medication three times during the two week period, she was asked to continue the treatment and return in another two weeks for another blood test.

After the next couple of weeks, the blood tests still showed no improvement. This time my mother had NOT missed taking her medication, but the nurse didn't seem to believe us.

Consequently, the doctor increased the dosage. My mom was having negative side effects due to the increased dose, including shortness of breath, palpitations, and just feeling totally out of sorts. As a result, she called the doctor and said that she could/would not continue with that dose. The doctor put her back on the smallest dose of Synthroid, but again the blood tests were showing no improvement.

We asked if perhaps something she was eating might be interfering with absorption of the medication, but the doctor and the nurse both said, "no".

I thank God for your website, for it provided me with the answer as to what was going on!!!! After extensive research we discovered that CALCIUM PREVENTS ABSORPTION OF THYROID MEDICINE. MY MOM WAS TAKING HER VITAMIN AND CALCIUM SUPPLEMENT AT THE SAME TIME THAT SHE WAS TAKING HER THYROID MEDICATION. It was that simple Mary!!!! She followed the guidelines regarding taking supplements, waited 4 weeks instead of 2 weeks before going back for her blood test, and for the FIRST TIME her TSH levels were normal.

When I told the doctor and the nurse what we had discovered on YOUR website, and how my mom had separated her calcium and thyroid supplement, they looked at me like I was full of it. They had never heard of this before. They assumed that the tests were normal because she hadn't skipped a day of taking her meds like they had advised her!

This is such a simple fact but, WITHOUT YOUR WEBSITE, Mary, we would never have known this!! AREN'T DOCTORS SUPPOSED TO KNOW THESE THINGS???? Can you imagine what my mom would have gone through as they would have kept fiddling with the dosage until her TSH levels were normal??? WOULD THEY EVER HAVE GOTTEN NORMAL??? (She is 73 years old.) How many other women are going through these UPS and DOWNS because their doctors are UNAWARE that calcium supplements interfere with thyroid medication???!!!

THANK YOU SO MUCH MARY!!! I read your newsletter religiously. You are a lifesaver for many women out there who have thyroid problems!! I know for a fact that you may have saved my mom's life!!! KEEP UP THE GOOD WORK! and God bless you.

Calcium does in fact interfere with your ability to absorb thyroid hormone medication. So keep these guidelines in mind: 

If you are taking any calcium supplements -- including antacid supplements like Tums that contain calcium -- take them at least three to four hours apart from your thyroid medication.

Be careful about calcium-fortified drinks, like orange juice, and again, be sure to take them at least three to four hours apart from your thyroid medication. 

You should also be careful about overdoing other calcium-rich foods around the same time as you take your thyroid medication. Some popular foods high in calcium include:

  • Milk
  • Yogurt
  • Cheese
  • Sardines
  • Dark leafy green vegetables including spinach, kale, turnips, and collard greens. (Note: when raw, these are also thyroid-slowing goitrogens.) 
  • Some calcium-fortified  breakfast cereals (i.e., Raisin Bran, Corn Flakes and Total.) 
  • Soybeans
  • Calcium-foritified soymilk, almond milk, and rice milk. 


    For more information on how to take your thyroid medications -- including issues involving coffee, and fiber and their ability to affect your thyroid -- see the resources in the sidebar on the right, and in particular, How To Take Your Thyroid Medication.

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