Thyroid Tests Influenced by Cholesterol-Lowering Statins

Scientists have discovered that cholesterol-lowering statins, used to treat and prevent atherosclerosis, may falsely indicate thyroid problems.

Investigators reexamined 307 patients whose initial TSH blood tests, the most common measure of thyroid function, showed overactive thyroids. Symptoms of the condition, called hyperthyroidism, include a fast heart rate and palpitations, tremors, anxiety, weak muscles, and difficulty sleeping.

More specialized diagnostics with radioactive iodine were used in the new study than the previous simple TSH tests. These new tests showed that the majority of patients on statins who appeared to be hyperthyroid by TSH tests actually had normal thyroid function. The tests also confirmed that the majority of patients not taking statins did have thyroid problems, as the initial TSH tests suggested.

"These findings could help physicians make quicker, more accurate diagnoses of suspected thyroid problems," said Dr. William Harvey, a nuclear medicine physician and author of the study. "It also has very provocative scientific implications as we learn more about how statins affect different systems in the body."

Hyperthyroidism affects about 4 million people in the United States. Graves' disease is the most common form of the condition, which occurs when the body's immune system mistakenly attacks the thyroid gland.

Dr. Mark Feldman, chairman of internal medicine at Texas Health Dallas (USA) and the study's senior author, said, "These findings are fascinating because there's a possibility that statins may improve thyroid function in patients with overactive thyroids."

The study appeared in the October 2008 issue of the journal Thyroid.

Texas Health Dallas


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