DALLAS, April 1, 2010 Young adults with overactive thyroid face a 44 percent increased risk of stroke compared to those with normal thyroid function, according to a study reported in Stroke: Journal of the American Heart Association.
"Strokes of undetermined cause account for between one-third and one-fourth of all ischemic strokes in young people," said Herng-Ching Lin, Ph.D., senior author of the study and professor at the School of Health Care Administration, College of Medicine, Taipei Medical University in Taipei, Taiwan. "To the best of our knowledge, hyperthyroidism has never been considered as a potential risk factor for stroke in the 18 to 44 age group."
Hyperthyroidism, also known as overactive thyroid, is a common endocrine disorder that affects an estimated 0.5 percent (1 in 200 people) to 2 percent (1 in 50 people) of the world's population, including a significant group of young adults, Lin said. The condition causes overproduction of thyroid hormone, which speeds up the metabolism and causes symptoms such as sweating, weight loss, diarrhea and nervousness.
For the study, researchers used data on 3,176 young adults diagnosed with hyperthyroidism between Jan. 1, 1998 and Dec. 31, 2001, and 25,408 comparison patients free of thyroid disease who were treated under Taiwan's national, single-payer healthcare system. The patients' average age was 32.
The researchers tracked each patient's data for five years to identify those who developed ischemic stroke, the most common type of stroke caused by blocked arteries in or leading to the brain. During those five years, 198 of the 28,584 patients developed ischemic stroke (0.7 percent), including 31 (1 percent) of the hyperthyroidism patients and 167 (0.6 percent) of the comparison group, Lin said.
After adjusting for factors including patient age, gender, income, level of urbanization, high blood pressure, diabetes, an irregular heart rhythm called atrial
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American Heart Association