An underactivity of the thyroid gland, hypothyroidism, is quite common—affecting probably one percent of the population and rising to five percent over the age of 60. The thyroid gland is responsible for controlling the metabolic rate of most of the body. When the rate slows, both mental and physical systems are involved. In its severest form, called myxedema, it is capable of causing permanent dementia and even death. Thankfully, however, it is generally an easily treatable disorder.
Hypothyroidism is more common in females than males, as much as five to one, and is usually recognized by symptoms in the 30s and 40s. Often times it is the result of an autoimmune process, when the body produces antibodies which destroy the cells of the thyroid for unknown reasons. The autoimmune version is known as Hashimoto’s thyroiditis and is generally slow in onset. Measurement in blood of thyroid autoantibodies confirms this diagnosis, along with low thyroid function results. People who have been hyperthyroid, or with an increased thyroid function, are often rendered hypothyroid as the result of treatment; this is whether through drugs, surgery, or the use of radioactive iodine to destroy the overactive gland. Certain types of inflammation of the gland (called thyroiditis) often result in hypothyroidism when the primary process resolves. Less common causes involve the pituitary gland in the brain, which is the feedback center for when to have thyroid hormone released or inhibited.
Hypothyroidism is usually a slow onset disease which can take months to years to diagnose as the process is often quite slow. Mild hypothyroidism may not even show up on blood testing—in fact since every person’s thyroid “set” is an individual one, a “normal“ blood result can still be hypothyroid if it is less than the original values that the body was used to. Initial symptoms include weight gain, water retention, depression, weakness and muscle discomfort. Hair can become more coarse and brittle, and affected people become cold intolerant. Heart rate generally slows and blood pressure rises. Dry, almost craggy skin ensues, and the doctor may be able to feel an enlarged thyroid gland on physical examination.
Hypothyroidism is a difficult diagnostic dilemma in older age. A slow, sad looking, somewhat confused individual may not be suffering from the inevitable effects of aging, or dementia, but may just be clinically and profoundly hypothyroid. Screening for thyroid disease is a must in this setting when individual behavior patterns change for no apparent or discernible reason. If treatment isn’t instituted in a reasonable period of time, the dementia, cardiac abnormalities, and hypertension can become permanent.
Generally symptoms can be put together to arrive at a diagnosis, and increasingly screening blood tests are done which may diagnose the problem before the problem is clinically apparent. Blood thyroxine levels (also called T4) are drawn, but because it’s normal range is wide it’s not always the best test to use for screening. TSH (thyroid stimulating hormone) is produced in the pituitary gland in the brain and is the sensing center for the amount of thyroid needed by the body—too little thyroid causes TSH to rise (to stimulate the gland to increase production and release) and too much slows down the release mechanism. TSH measurements are the best way to diagnose hypothyroidism, and combined with the thyroid measurement provide a good pair to guide treatment.
Once diagnosed, thyroid replacement or augmentation is quite easy—given as an oral tablet, the amount can be adjusted to put the body in an appropriate set. The purpose is to replace thyroid hormone—too much hormone given to try to rev up body metabolism or lose weight doesn’t work as it is catabolic and breaks down muscle as much as anything else. The dose is easily adjusted by blood testing and how the patient is feeling.
If caught appropriately and permanent changes have occurred, standard issue is the rule and preferred consideration is open for those who are successfully on long term replacement therapy with normal blood testing and no complications such as cardiovascular or cognitive disease. It is lifetime therapy though, so while it is not fatal if you miss a few doses (the average half life of the most common replacement medicine is a week, meaning you have 50% of the dose still in your body if a week is missed) compliance is very important for long term health and well-being.
