What is Hypothyroidism?
Hypothyroidism is a condition characterized by abnormally low thyroid hormone production. There are many disorders that result in hypothyroidism. These disorders may directly or indirectly involve the thyroid gland. Because thyroid hormone affects growth, development, and many cellular processes, inadequate thyroid hormone has widespread consequences for the body.
What are the Symptoms of Hypothyroidism?
The symptoms of hypothyroidism are often subtle. They are not specific (which means they can mimic the symptoms of many other conditions) and are often attributed to aging. Patients with mild hypothyroidism may have no signs or symptoms. The symptoms generally become more obvious as the condition worsens and the majority of these complaints are related to a metabolic slowing of the body. Common symptoms are:
- Modest weight gain
- Cold intolerance
What Causes Hypothyroidism?
Hypothyroidism is a very common condition. It is estimated that 3% to 5% of the population has some form of hypothyroidism. The condition is more common in women than in men, and its incidence increases with age. Below is a list of some of the common causes of hypothyroidism in adults followed by a discussion of these conditions:
- Hashimoto's thyroiditis
- Lymphocytic thyroiditis (which may occur after hyperthyroidism)
- Thyroid destruction (from radioactive iodine or surgery)
- Pituitary or hypothalamic disease
How is Hypothyroidism Diagnosed?
A diagnosis of hypothyroidism can be suspected in patients with fatigue, cold intolerance, constipation, and dry, flaky skin. A blood test is needed to confirm the diagnosis. When hypothyroidism is present, the blood levels of thyroid hormones can be measured directly and are usually decreased. However, in early hypothyroidism, the level of thyroid hormones (T3 and T4) may be normal. Therefore, the main tool for the detection of hyperthyroidism is the measurement of the TSH, the thyroid stimulating hormone. As mentioned earlier, TSH is secreted by the pituitary gland. If a decrease of thyroid hormone occurs, the pituitary gland reacts by producing more TSH and the blood TSH level increases in an attempt to encourage thyroid hormone production. This increase in TSH can actually precede the fall in thyroid hormones by months or years (see the section on Subclinical Hypothyroidism below). Thus, the measurement of TSH should be elevated in cases of hypothyroidism.
How is Hypothyroidism Treated?
With the exception of certain conditions, the treatment of hypothyroidism requires life-long therapy. Before synthetic levothyroxine (T4) was available, desiccated thyroid tablets were used. Desiccated thyroid was obtained from animal thyroid glands, which lacked consistency of potency from batch to batch. Presently, a pure, synthetic T4 is widely available. Therefore, there is no reason to use desiccated thyroid extract.
If you are concerned that you may have hypothyroidism, you should mention your symptoms to your physician. A simple blood test is the first step in the diagnosis. From there, both you and your doctor can decide what the next steps should be. If treatment is warranted, it is important for you to let your doctor know of any concerns or questions you have about the options available. Remember that thyroid disease is very common and, in good hands, hypothyroidism is easily addressed and treated.