You feel tired, your periods are irregular or you have gained weight. Your health care professional orders a blood test and diagnoses hypothyroidism, or a slow or low thyroid. You are told to take a hormone pill once a day, and that will fix your condition.
That’s all many women hear about their diagnosis or synthetic thyroid hormone. But there are a few more things that you need to know about this little pill and how to avoid problems.
Hypothyroidism occurs more frequently in women than men. Seventeen percent of women and 8% of men develop hypothyroidism by age 60. It is most often the result of an autoimmune condition called Hashimoto’s thyroiditis that leads to destruction of the gland.
We need thyroid hormone to maintain our metabolism and keep many of our routine body functions and temperature normal. Having too much thyroid hormone can stress your heart, causing abnormal heart rhythms or even a heart attack. It also can lead to bone loss and osteoporosis. Having too little thyroid hormone makes you feel tired and gain weight, and it throws off your hormonal balance for your periods. Once you take thyroid hormone, you will always need to take thyroid hormone.
How To Take Your Thyroid Hormone
If you already take your hormone pill with food or other medications, don’t change your routine if your hormone levels have been fine. But for people who just can’t seem to get on the right dose of medication, certain foods or other medications may be the culprits. Your ability to absorb thyroid hormone can easily be impaired by things you eat and other drugs or supplements that you take. In particular, calcium, iron tablets, iron in multivitamins and the cholesterol-lowering medications cholestyramine and colestipol can interfere with thyroid hormone absorption.
For the above reasons, it is usually better to take your thyroid medicine on an empty stomach and at least three to four hours apart from taking other medications. For many people, the best time to take thyroid hormone is at bedtime. To help you remember to take it each night, put it next to your toothbrush or something else you do regularly before you go to sleep. Thyroid hormone won’t interfere with your ability to sleep.
In general, generic thyroid pills can be trusted and work as well as the brand-name products. If you do switch from one brand or one generic to another, ask your doctor to order a blood thyroid test four to six weeks after making the change.
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Symptoms of the Wrong Dose
If you are taking too much hormone, you might feel palpitations, heart racing, or, in severe cases, chest pain. Unexplained weight loss and diarrhea also might be from too much thyroid hormone. If you are not getting enough hormone, you might gain weight, feel tired or have constipation. Getting puffy around the eyes, and arm and leg swelling might be from too little hormone. Women also might notice irregular periods or very long and heavy periods. Any time you notice these symptoms, get a blood test to check your thyroid hormone level.
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Women who take estrogen: If you start taking estrogen, either for birth control or for menopausal symptoms, you will probably need to increase the amount of thyroid hormone you take. One month after you start an estrogen-containing medication, get a blood test to check your thyroid-hormone level to make sure your medication dosage is within the desired range.
Pregnancy: It is very important to discuss thyroid-hormone dosing with your health care professional even before you start trying to become pregnant. The fetus is dependent on the mother’s thyroid hormone for normal neurological development in the first trimester. It takes about 12 weeks before the fetus’ own thyroid gland develops and produces thyroid hormone. Because of the higher levels of estrogen produced during pregnancy, your thyroid gland normally produces more thyroid hormone to compensate. Also, when the thyroid is functioning normally, certain pregnancy hormones stimulate the gland to produce greater amounts of hormone. Since you are taking thyroid hormone pills, you will need to do what the body would ordinarily do naturally — increase the dose of your hormone pills. Since women often discover they are pregnant after one or two months of being pregnant, you will want to test for pregnancy the day you miss your period to confirm your pregnancy as soon as possible and start testing your thyroid-hormone levels right away.
During the first trimester, your thyroid hormone levels should be followed carefully, at least once a month. Talk to your health care professional about how to change doses of your thyroid hormone as soon as you discover you are pregnant.
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The Bottom Line
Although there are only a few extra considerations about thyroid hormone for women, they are important ones. Fortunately, most solutions are as simple as taking an extra blood test to make sure your levels are normal and that you are taking the right dose of medication. After reading this, you can file these facts in the back of your brain and just remember to ask about checking your level with any new medications or new symptoms. Most importantly, talk with your doctor and make a plan regarding your thyroid dose before you become pregnant. Be sure to call for advice as soon as you find out you are pregnant.
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Alice Y. Chang, M.D. is a former instructor in medicine at Harvard Medical School. She is currently associated with University of Texas Southwestern Medical Center. Her clinical interests and experience are in the fields of primary care, women's health, hospital-based medicine and patient education.