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The thyroid epidemic

Is there an invisible epidemic sweeping the country? Thyroid dysfunction is one of the most common health problems in America, and no one knows why it has become so widespread.

At last count, about 100 million prescriptions were filled annually for thyroid hormone in the form of levothyroxine (Levothroid, Levoxyl, Synthroid, Unithroid) or Armour Thyroid. That makes thyroid medication one of the most dispensed drugs in the pharmacy.

Did our ancestors also suffer from thyroid disorders at a high rate? Some experts think they did, but went undiagnosed.

Others blame environmental chemicals. Hormone-disrupting chemicals, including flame retardants and stain repellents, have been associated with underactive thyroid (Environmental Health Perspectives online, March 27, 2012).

The iodine-containing contrast medium used in some CT scans and heart procedures also can disrupt thyroid function (Archives of Internal Medicine, Jan. 23, 2012). In high doses, the active ingredients in soy products (isoflavones) also may affect the thyroid.

Whether or not these environmental factors are contributing to thyroid disease, many patients feel frustrated by the difficulties they encounter in diagnosis and treatment. One reader wrote: "My doctor doesn't believe my thyroid is causing my symptoms of fatigue, feeling cold all the time, thinning hair, dry skin and brittle nails. I cannot lose weight no matter how little I eat. My TSH is 4.7, and my doctor says that's normal, but I feel terrible."

A husband wrote to inquire about his wife's symptoms of fatigue, joint and muscle pain, poor sleep, hoarseness, cold hands and feet and an inability to lose weight even with exercise and diet. He wondered if such symptoms could be thyroid related. The symptoms described by both readers are classic for hypothyroidism.

There is significant controversy within medicine about diagnosing thyroid dysfunction. The standard approach is to assess TSH (thyroid-stimulating hormone). Elevated TSH suggests that the thyroid gland is underperforming.

The controversy concerns the cutoff at which TSH is considered high. When the normal range was first established, it ran from 0.4 to 5. Now, many endocrinologists think that a more appropriate range tops out at 3 or even 2.5. And TSH may not be the only relevant test.

For more details about diagnostic testing and treatment of thyroid problems, readers may wish to listen to our one-hour interview of three thyroid experts. It can be streamed for free from (No. 853), or a CD can be obtained for $11.99 from The People's Pharmacy, CD-853, P.O. Box 52027, Durham, NC 27717-2027.

Treatment of low thyroid can be just as controversial as diagnosis. Conventional wisdom maintains that a prescription for levothyroxine, known as T4, solves the problem. But many patients report that pure T4 doesn't eliminate their symptoms. Some physicians prescribe a combination of T3 and T4 either as desiccated thyroid (Armour Thyroid) or a slow-release formulation compounded for the individual patient.

Correcting thyroid dysfunction can dramatically improve quality of life. Even if doctors don't yet know what's causing the epidemic, they still can work with each patient to ease symptoms.