Q: I am 72-year-old lady in relatively good health. Usually, I go to my doctor only once or twice a year. I take medication for high blood pressure and another one to lower my cholesterol. My problem started about six months ago. I had not been feeling well for a while. I was very tired all the time and had problems sleeping. When I went to my doctor, he did some blood work and told me that all of my symptoms were due to an underactive thyroid. I just started new medication to correct the imbalance, but I have read that it can be dangerous to take too much of it. My daughters joke about me being such a scaredy cat, but for me this is actually quite serious. What is the best way to do this correctly and is there any risk in taking this new medication?


A: Taking any new medication and learning about any new diagnosis may be quite scary. There is no shame in seeking more information and being extra careful.

We have two kinds of thyroid hormones in our body -- thyroxine, or T4, and triiodothyronine, or T3. Thyroid hormones are secreted by a butterfly-shaped gland in the middle of our neck called thyroid gland. It is a fascinating organ. Its hormones are essentially responsible for regulating our body's metabolism, or the speed with which our body functions. Many specific things are influenced by the thyroid hormones. Our heart rate, the way we burn fat and carbohydrates, our core body temperature and so on are all under at least partial control of thyroid hormones.

There are a few ways to become deficient in thyroid hormones. In less-developed countries, it can be caused by a lack of iodine in the diet. Iodine is an essential element needed for the proper production of thyroid hormones. Before we knew that iodine was so important in making the thyroid work properly, many young children were permanently affected by low thyroid hormones, both mentally and physically.

Since iodine has been added to many foods (mostly salt and seafood) in this country for quite some time now, diet deficiencies are less of a concern. However, some in this country are afflicted by an autoimmune disease called Hashimoto's thyroiditis, which can affect the thyroid. What happens is that our body starts producing proteins called antibodies, which attack and destroy thyroid-hormone-producing cells. The majority of hypothyroidism, or low thyroid, patients are women over 60, but it can happen to anyone -- even children. Some people can get low thyroid hormone levels after their thyroid gland is removed. It can also happen as a result of radiation therapy for other diseases, such as cancer. Thyroid gland can slow down after being attacked by a virus, although this condition is rare. There are also some medications that can be responsible. Some women can develop low thyroid hormone levels after delivering a baby.

The initial symptoms of underactive thyroid can be quite obscure. A slower pace of our body's functioning can manifest in many ways, including a poor tolerance to cold, weight gain, constipation, dry skin, fatigue and even depression and slower thinking. Thinner hair, body aches, and elevated cholesterol can also be present. It is extremely important to talk openly with your doctor early if you start feeling strange or different. The simplest way to check for an underactive thyroid is through blood work. What doctors check is the level of a regulatory substance called thyroid-stimulating hormone or TSH. This hormone is produced by our brain, specifically by a tiny gland inside it called pituitary. Pituitary gland secrets many other substances all designed to control hormones in our body. When thyroid gland is underactive the level of regulatory TSH increases. This increased level can be easily checked in the blood, telling doctors what went wrong. We also have ways of detecting exact levels of T4 and T3, as well as the levels of antibodies attacking our own thyroid gland. Your physician will also review all of your medications and supplements to make sure that another medication is not responsible for low thyroid hormone levels. Sometimes high levels of TSH may cause overgrowth of the thyroid gland. This overgrowth, which can be detected during a physical examination, is called a goiter.

There is also a condition called subclinical hypothyroidism. This is when the thyroid gland is only slightly off, so the thyroid hormone levels are within normal limits, while TSH is just slightly high. In this situation, a doctor usually will discuss with the patient whether or not to start a thyroid hormone supplement.

Once the diagnosis is made, the treatment of underactive thyroid is not difficult. It consists of taking supplemental, synthetically-made levothyroxine. Some people may still be using an older preparation of a thyroid hormone supplement, made from glands of pigs, but these days most have switched to a purer option. Symptoms of low thyroid will improve within just few weeks once supplementation starts. Maria is right, though -- one has to be careful not to overdo the treatment. It is possible to go from having not enough of the thyroid hormone to having too much of it. Over supplementation can cause weight loss, brittle bones, fast heart rate and other problems. This is why a person who takes a thyroid hormone supplement will need to have blood work done at least few times a year to make sure that the dose of the hormone is correct. The supplemented hormone will need to be taken for the rest of someone's life.

I am glad that Maria is conscientious about her new diagnosis and new medication. I want to assure her, however, that taking the supplemental thyroid hormone will be easy. Blood work may be initially needed slightly more often, just to get the proper dose of the levothyroxine for her, but most patients end up only needing the re-check once or twice a year. Working with Maria's primary doctor is the way to go.
