Thyroid Hormone Primer

Hormones always interact with and affect other hormones. Your pituitary gland releases thyroid stimulating hormone (TSH) to begin and maintain production of thyroid hormones. The thyroid makes T4 first, and then, through a family of highly specialized enzymes, T4 gets converted to T3.

It all sounds simple enough, but things can go wrong – and go unnoticed. Infections, injuries, prediabetes, type-2 diabetes, chronic inflammation, alcohol and drug abuse, surgery, and the aging process itself can impact thyroid activity, according to Ron Hunninghake, M.D., a nutritionally oriented physician in Wichita, Kansas. 

Most physicians will measure TSH levels to determine thyroid function. If TSH levels are elevated, it’s a clear sign of low thyroid activity. In effect, the pituitary gland keeps sending out more signals to make thyroid hormones. However, a normal TSH won’t reveal more subtle signs of low thyroid, sometimes referred to as subclinical hypothyroidism.

Doctors will also commonly measure a patient’s T4 levels. However, T4 is relatively inactive as a thyroid hormone. The body must convert it to T3, which is the most biologically active thyroid hormone. If you suspect some form of low thyroid activity, you can perform the basal temperature test at home. You’ll need to use an old-fashioned oral glass thermometer (non-mercury types are still sold at drug stores). When you go to bed, shake it down and keep it within easy reach. As soon as you wake up in the morning, while moving as little as possible, slip the thermometer in the fold of your armpit and leave it there for 10 minutes. Write down the temperature, and do this for three to five days in a row. If you’re a woman, don’t do this test during your menstrual period or when you’re ovulating because your body temperature will be higher at these times.

Add all of the basal temperatures, and then divide by the number of days to obtain an average. Normal basal temperatures range from 97.8 to 98.2 degrees. If your average temperature is 97.7 degrees or less, you are probably hypothyroid. If that’s the case, ask your doctor to run additional tests to confirm and pinpoint the specific problem.

The key at this point is to assert yourself and ask your doctor for a full thyroid “panel,” specifically to test for free T4, free T3, and TSH. (Free T4 and free T3 are unbound hormones.) Request a copy of the report from your doctor’s office. This report will list your levels plus the range of normal levels. Low or low-normal T3, T4, or both, is a definite sign of low thyroid. But this is what’s often missed: If your T4 is normal, but your T3 is either low or low-normal, your body is not efficiently converting T4 to T3. One other bit of advice: When you ask your doctor to order a thyroid panel, ask him or her to add a test for “reverse T3.” This test is especially important if you have been under a lot of stress. That’s because high levels of stress hormones interfere with the conversion of T4 to T3 and instead boost production of reverse T3. Reverse T3 does not function as a real thyroid hormone. Instead, it inhibits the activity of T3.

Nutritional Supplements That Support a Healthy Thyroid

Three nutrients have the greatest bearing on your thyroid hormone levels: L-tyrosine, iodine, and selenium. You need adequate amounts of these three nutrients to make and use thyroid hormones. 

L-tyrosine 

This amino acid (protein building block) forms part of the chemical foundation of your thyroid hormones. It’s also a building block of the body’s stimulating neurotransmitters, including adrenaline and dopamine. Consider taking 500 mg of L-tyrosine immediately on waking, about 10 to 15 minutes before consuming any food or liquid other than water. You can take larger amounts if your naturopathic or nutritionally oriented physician thinks they would be helpful.

Caution:

If you have hypertension, monitor your high blood pressure after taking L-tyrosine because it may increase blood pressure. Stop taking L-tyrosine if you develop an unsafe increase in blood pressure.

Iodine

This essential dietary mineral also forms part of the foundation of your thyroid hormones. T4 contains four iodine atoms, and T3 contains three iodine atoms. Consider starting with a low amount of iodine, such as 200 mcg (micrograms) a day and be sure to include selenium since it helps to balance iodine’s effects on the thyroid (see the next paragraph).  Also, because iodine may actually exacerbate autoimmune thyroiditis (such as Hashimoto’s) it is imperative to rule out thyroid autoimmunity before adding an iodine supplement. Work with an experienced practitioner if you have an autoimmune thyroid condition, are unsure if you have an autoimmune thyroid condition, or if you wish to try higher doses of iodine. 

Selenium 

You need selenium to make the enzymes that convert T4 to T3. A two-year study conducted at the U.S. Department of Agriculture’s research center in Grand Forks, North Dakota, found that taking 200 mcg of supplemental selenium significantly increased T3 levels in men and slightly increased 

its levels in women.¹ Meanwhile, a European study reported that 200 mcg of selenium daily effectively reduced antibodies and improved mood and well being in people with Hashimoto’s thyroiditis.² As a general rule, 200 mcg of selenium – an amount found in most multivitamins – is sufficient to improve thyroid function. You can increase your selenium intake to 400 mcg daily, but do not go above this amount without specific guidance from your physician.

Vitamin D

A study by researchers in Istanbul, Turkey, found that vitamin D deficiency was present in 92 percent of patients with Hashimoto’s thyroiditis. By comparison, vitamin D deficiency was identified in only 63 percent of people without the disease. Try taking 5,000 IU daily of vitamin D.³

Multivitamin/multimineral

Other important nutrients in thyroid activity include vitamins B6 and B12, and the minerals zinc, chromium, and iron. You can obtain adequate amounts of these nutrients in a quality multivitamin/multimineral supplement. 

Glandular supplements 

Glandular supplements contain thyroid tissue that has been frozen and then dehydrated before being encapsulated. Some glandular supplements are obtained from range-fed animals. These products are best taken under the guidance of a physician, but they are available without a prescription.

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