Smoking increases both the risk and severity of Graves' disease, a thyroid condition, researchers have reported.
Quitting smoking might prevent development of the disease in people with a famly history of Graves' disease, they said Tuesday.In a study of 450 patients with Graves' disease, researchers found those who smoked were nearly eight times more likely to suffer from one of the disease's more severe symptoms, including enlarged tissue around the eyes and blurred vision.
Smokers also outnumbered nonsmokers nearly two to one among patients with less serious manifestations of the disease, according to Dr. Mark Prummel of the Veterans Affairs Medical Center in San Francisco and Dr. Wilmar Wiersinga of the University of Amsterdam.
"Smoking is associated with Graves' disease, and it especially increases the risk for the development of more severe opthal-mo-pathy. Thus, smoking appears to be one of the multiple factors inducing Graves' disease in genetically predisposed individuals," said the doctors in the Journal of the American Medical Association.
While the study did not analyze how smoking boosts the Graves' disease risk, the researchers believe smoking somehow triggers the immune system defect that causes the thyroid to malfunction.