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Treatment of Subclinical Hypothyroidism Advocated: Presented at ACP

By Jane Salodof MacNeil

SAN DIEGO, CA -- April 7, 2003 -- Subclinical hypothyroidism can lead to overt hypothyroidism and should be treated, according to David F. Gardner, MD, a professor of medicine, division of endocrinology, Virginia Commonwealth University School of Medicine, in Richmond.

"Is subclinical hypothyroidism bad for you? That is the fundamental issue," Dr. Gardner said, describing the controversy over treatment in a presentation at the 2003 Annual Session of the American College of Physicians (ACP), held here April 3-5.

He noted that the ACP has not taken a position for or against treatment of subclinical hypothyroidism, as the available evidence is insufficient to support or reject therapy.

Also known as mild thyroid failure or compensated hypothyroidism, the condition may be more common and more symptomatic than is generally accepted, according to Dr. Gardner.

Patients with subclinical hypothyroidism typically have elevated thyroid stimulating hormone (TSH) and normal serum thyroid levels. Though it is estimated to occur in 5% to 10% of the general population, Dr. Gardner said prevalence in women over the age of 60 could be as high as 15% to 20%.

Although patients with subclinical hypothyroidism are said to be asymptomatic, Dr. Gardner reported that many describe vague, nonspecific symptoms, including fatigue, depression, memory loss, and decreased energy. "If you ask the right questions, some of the patients may be quite symptomatic," he said.

Adverse effects fall into four general categories, according to Dr. Gardner -- neuropsychiatric symptoms, abnormal lipids, altered myocardial function, and greater risk of atherosclerotic heart disease. A recent study from the Netherlands has shown the last to be especially disturbing in elderly women, he said.

"Older patients are at great risk of progression [to overt disease]," Dr. Gardner continued. "The most important benefit [of treatment] is you can prevent patients from going on to overt hypothyroidism."

He cited one study in which 55% of women progressed during 20 years of follow-up, and another in which 80% of patients over 65 progressed within 4 years.

Dr. Gardner said a definitive answer to the treatment issue is not currently available but that he recommends therapy for patients with TSH levels greater than 10 U/mL, thyroid abnormalities, vague symptoms that might be attributable to hypothyroidism, a history of radioactive iodine treatment or surgery for Graves disease, a psychiatric disorder, or pregnancy.

If a patient is not treated, he should be closely monitored, Dr. Gardner said. Adding to the controversy, he added, is growing evidence that the upper limit of normal serum TSH concentration should be less than 2.5-3.0 U/mL and not the current levels of 5.0-5.5 U/mL.

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