Thyroid Failure:Hashimoto’s Disease

When I was a resident in medical training a woman arrived in the emergency room in a coma. She had been living alone and, according to neighbors, sitting in a chair in her apartment for weeks. Her clinical state was like one of hibernation, with very low pulse, blood pressure and temperature. Her hair was like thin and brittle, her skin scaly and dry, her face puffy and her legs thickened by a waxy swelling called myxedema. She was in the final stages of thyroid gland failure, myxedema coma. Early in the course of her illness, when symptoms were probably mild and ill-defined, no one had realized she was “hypothyroid.” Later, when thyroid hormone levels had fallen to dangerous lows, she was too slow mentally and physically to seek help. By the time she arrived in the ER she was on the brink of death from Hashimoto’s disease, an autoimmune inflammation of the thyroid gland, or thyroiditis. Hashimoto’s disease was the first recognized disease caused by the immune system attacking some part of the body, and is the most common cause of thyroid gland failure in the USA.

Hashimoto’s disease affects at least one in every 1000 people in the US, women more frequently than men.  Though the thyroid disease was first described in 1912, and is now known to be caused by the production of antibodies against thyroid hormone producing enzymes and proteins, there is still no known way to prevent it. The only risk factor is a family history of a similar problem. Some environmental factors such as high iodine intake and viral infections may play a role in triggering the process in genetically susceptible individuals. In Hashimoto’s disease, the antibodies gradually destroy the gland’s hormone producing follicles. Most often, the thyroid gradually and irregularly enlarges as the follicles are replaced by inflammatory tissue. While the bumpy neck bulge created is similar to a goiter, the latter is smoother and more regular in shape and a sign of an overworking but non-inflamed thyroid gland which is getting insufficient dietary iodine.

In Hashimoto’s disease, subtle physical symptoms often precede the development of an enlarged thyroid gland. Since thyroid hormone facilitates all metabolism and energy production in every part of the body, inadequate amounts of the hormone cause a host of vague symptoms which are often excused as simply the byproduct of life style inadequacies such as too little sleep, poor diet, lack of exercise and stress. The symptoms include fatigue, weight gain, depression and anxiety, inability to stay warm, joint and muscle aches and pains, constipation, slow pulse, coarse and thinning hair, puffiness, irregular menstrual periods, and inability to conceive. In some people, gland enlargement never occurs. And though the underlying problem is inflammatory, the thyroid gland is not tender.

Because of the vague nature of the symptoms that bring a patient with Hashimoto’s thyroiditis to the doctor, because the thyroid gland may not be enlarged and because the screening blood test for total thyroid hormone level may fall within a normal range, many other diagnoses are often entertained before the correct one is made. These include depression, anxiety, chronic fatigue syndrome and subclinical infection. In addition, because hypothyroidism drives cholesterol and weight up, attention gets diverted to heart disease and other components of the metabolic syndrome.

But once suspicion of Hashimoto’s has been raised, the problem is easily identified by blood tests for antibodies to an enzyme called thyroid peroxidase and to a thyroid hormone binding protein called thyroglobulin and a test for a pituitary gland hormone called TSH, or thyroid stimulating hormone.  TSH rises as thyroid function fails and the pituitary gland attempts to stimulate it to keep producing thyroid hormone.

Some patients need thyroid scans and biopsies of any suspicious gland areas to rule out the very rare possibility that a lump in the gland is cancerous. A general medical evaluation is also helpful since low thyroid hormone can accelerate cardiovascular disease and since the autoimmune dysfunction underlying Hashimoto sometimes occurs in association with other autoimmune disorders such as celiac disease, Type 1 diabetes, adrenal gland insufficiency, autoimmune gastritis with Vitamin B12 deficiency, rheumatoid arthritis, lupus, and some clotting disorders that may cause either bruising or clot formation in blood vessels.

If other autoimmune problems are not found, the therapy for Hashimoto’s thyroiditis is as easy as taking one pill a day, usually a synthetic thyroid hormone called levothyroxine. Prior to the development of synthetic thyroid hormone, a desiccated powder made from pig thyroid glands was the only treatment available and it is still preferred by a significant number of patients. A controlled study done in 2013 to determine whether there was any scientific evidence for treatment preference showed that both synthetic thyroid hormone and desiccated thyroid hormone are equally effective in raising thyroid hormone levels and returning TSH levels to normal, but that desiccated thyroid hormone resulted in slightly greater weight loss.

Our myxedema coma patient survived, though her management was difficult because of the severity of her hypothyroidism. Under the autoimmune attack of Hashimoto’s thyroiditis, the thyroid gland is a victim of a very slow war of attrition as more and more of its structure is replaced by inflammatory cells and scar tissue.  The fall-off in hormone production is slow, and the body adapts to lower and lower levels of thyroid hormone until all systems finally begin shutting down. At that point, re-introducing high levels of thyroid hormone can be dangerous to heart function. The correction must occur gradually, as the decline did, underscoring the importance of detecting thyroid gland failure early, before it takes such a metabolic toll. Even when discovered early, the establishment of appropriate hormone dose and the reversal of symptoms may take some time and patience. The hormone must be taken for the rest of a long and otherwise normal life.

 

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