Early in her husband’s presidency, first lady Barbara Bush began to lose weight. Her eyes became, in her own words “horrible and puffy” looking.” She had developed an autoimmune thyroid gland problem called Graves’ Disease. A few months later, the Bush‘s dog Millie came down with another autoimmune disease – lupus. The next spring, the president became ill with weight loss and a rapid, irregular heartbeat. Like Barbara he had Graves’ disease. Conspiracy theorists blamed Saddam Hussein for this outbreak of autoimmune disease in the White House, but thyroid experts saw nothing but coincidence. They admit, though, that they do not know what triggers antibody attacks against the thyroid gland, the most common cause of thyroid disease.
The many and varied symptoms of thyroid disease
Symptoms of thyroid disease most often involve effects of the hormones the gland makes. Thyroid hormone stokes the fire of metabolism, setting the rate of energy usage in every cell of the body and determining the basal metabolic rate (number of calories burned at complete rest).
Too much thyroid hormone causes hyperthyroidism; too little creates hypothyroidism. Extreme cases of either problem are easy to diagnose, but milder excess or deficiency states are much trickier and more common (an estimated 7-10% of adults have thyroid abnormalities). Hyperthyroid patients lose weight, become intolerant of warm environments and sweat profusely. Hair becomes thin and fine. The heart beats too fast and blood pressure rises, while muscles feel weak and hands shake. Sleep becomes elusive. On the hypothyroid end of the spectrum, lack of thyroid hormone banks the metabolic fires and drops the heat. Patients feel cold and become constipated. Incoming energy gets stored as fat; weight and cholesterol levels climb. Lethargy encroaches on daytime hours, and ambition and mental quickness decline. Both under and overactive glands can be enlarged and even visible as swellings just under the Adam’s apple.
The confirmation of the thyroid gland’s role in symptoms comes from blood tests that measure thyroid hormone levels. Extreme cases are easy to diagnose. Milder cases, with less impressive symptoms and “borderline” blood tests are trickier. Mild symptoms overlap many of life’s normal patterns that are unrelated to thyroid hormone: weight, blood pressure and cholesterol tend to go up with age; sedentary people frequently feel cold and constipated; women at menopause would sometimes like to abolish indoor heating, and physical and mental energy are always subject to lifestyle, happiness, and drug effects. The opinion of an endocrinologist is particularly helpful in interpreting borderline thyroid symptoms and lab values.
Thyroxin or T4 (with four iodine molecules) comes from the thyroid gland. Tri-iodothyronine (T3) comes from T4 when one iodine molecule is split off. Thyroid stimulating hormone (TSH), made in the pituitary gland, is like a thermostat that regulates how much T4 the thyroid gland makes. When T4 is too high, TSH goes down. When T4 is too low, TSH goes up. So hypothyroid patients have high TSH and low T4, and hyperthyroid patients have low TSH and high T4.
Symptoms suggesting hyperthyroidism, combined with high-normal T4 and T3 and low- normal TSH prompt further tests to look directly at the thyroid gland. Thyroid scans employ radioactive iodine and distinguish between glands that overproduce in all areas, ones that have nodules of overproduction, and enlarged glands that no longer make any hormone. Measurement of three different types of anti-thyroid antibodies further narrows the diagnosis.
The problems with the tests
Not all labs use the same ranges of normal values. Some rely on broad TSH ranges found in a random selection of apparently healthy people (0.32 -5.0 µIU/ml). Other labs use a much narrower range (.34-2.5µIU/ml) found in people who have been screened to rule out thyroid disease. So if you see a doctor who uses the first range and your TSH is 4.5, you might be told just to watch your weight, get better sleep, take a little blood pressure medicine and be rechecked in 6 months or a year. A doctor using the second might would give you a prescription for thyroid hormone. Treatment of hypothyroidism in these gray areas might normalize the blood tests without producing any clinically identifiable benefits. Nevertheless, it is wise to follow up on iffy test results because, over time, thyroid conditions may declare themselves further.
Autoimmune thyroid disease
Graves Disease and Hashimoto’s thyroiditis, caused by different types of antibodies, are the most common causes of thyroid problems and tend to run in families. In Graves ’ disease, the antibodies may also attack eye muscles and make them swell, producing the characteristic bulging eyes that Barbara Bush complained about. Graves disease most often begins with a hyperthyroid state that requires treatment to suppress overproduction of thyroid hormone or to obliterate the gland by radiation, producing hypothyroidism that requires treatment; sometimes Graves’ improves on its own but then goes on to hypothyroidism. Hashimoto’s disease most commonly bypasses the clinical hyperthyroid phase altogether and is the most common cause of hypothyroidism.
Lack of dietary iodine once caused many cases of hypothyroidism. The word cretin (slang for dunce, idiot) originated in a mountainous French region where iodine deficient soil and lack of iodine-rich seafood resulted in a high incidence of mental and physical retardation from hypothyroidism in babies. Thyroid hormone and the dietary iodine required to make it are critical for normal growth and development, especially of the brain. In modern societies babies are screened and treated for hypothyroidism, and iodized salt makes this essential element easily available so this once frequent deficiency is much less common.
Oral, synthetic versions of T3 and T4, or “natural” versions made from batches of pig thyroid glands make failing thyroid glands easily treatable. Synthetic versions are easier to regulate than are the natural ones. Finding the proper dose to return the blood tests to the normal range is often much easier than finding the dose and timing of pills that improves symptoms. The latter process is an inexact science that sometimes results in too much hormone effect.
Overactive glands are treated with medicines that shut them down, sometimes with radioactive iodine that kills the glandular cells and sometimes with surgery to remove the entire gland. The latter two treatments always produce hypothyroidism which then requires treatment with replacement hormones.
One study on thyroid disease prevalence estimates that there are 13,000,000 Americans with undiagnosed thyroid problems. Thyroid tests are now part of routine blood work, more problems will be caught and treated earlier, and more will be learned about triggers for autoimmune thyroid problems – eventually putting at least one conspiracy theory to rest.
Notes on less Common Thyroid Conditions
Lumps in the thyroid: These are common and most are benign nodules or cysts; sometimes they produce thyroid hormone and cause hyperthyroidism.
Viral thyroiditis (also known as sub-acute thyroiditis): self-limited illness with several weeks of hyperthyroidism, followed by several weeks of hypothyroidism, and then recovery of normal function.
Thyroid cancer: Uncommon. Rarely produces thyroid hormone so usually the diagnosis results from evaluation of lump in the neck or hoarseness; results from radiation exposure – as once was the practice for treating acne.
Pituitary Gland Tumors: Pituitary failure to produce TSH causes hypothyroidism; very rarely the pituitary overproduces TSH and causes hyperthyroidism.
Dietary Hyperthyroidism: At least one outbreak of hyperthyroidism came from meat contaminated with animal thyroid glands. Another rare cause is sudden, excessive iodine supplementation in a patient with underlying thyroid disease .