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Stroke Health Center

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Overactive Thyroid May Raise Early Stroke Risk

44% Increase Seen in Younger Thyroid Patients
WebMD Health News
Reviewed by Laura J. Martin, MD

April 1, 2010 -- Younger adults with overactive thyroids appear to have an increased risk for early stroke, new research finds.

Having the condition known as hyperthyroidism before the age of 45 was associated with a 44% increased risk of stroke in the study conducted by investigators with Taiwan’s Taipei Medical University.

Strokes are uncommon, but on the rise, in adults in their 20s, 30s, and 40s.

One recent study showed a dramatic increase in strokes among U.S. adults at the same time that stroke rates among older adults were declining.

Between the mid-1990s and 2005, the stroke rate increased from 4.5% to 7.3% in adults between the ages of 20 and 45, according to the data from Ohio and Kentucky.

As many as a third of strokes in younger adults have no obvious cause, Taipei Medical University’s Herng-Ching Lin, PhD, tells WebMD.

Hyperthyroidism is a risk factor for the heart-rhythm disorder atrial fibrillation in older adults, and atrial fibrillation is, in turn, a risk factor for stroke.

While overactive thyroid is suspected of contributing to stroke risk in the elderly, its potential role in strokes occurring in younger adults had not been studied until now, Lin says.

Overactive Thyroid and Stroke

Lin and colleagues compared outcomes among Taiwanese adults under age 45 with and without hyperthyroid disease.

A total of 3,176 patients with a new diagnosis of overactive thyroid and 25,408 people without thyroid disease were included in the study.

During five years of observation, 198 people (0.7%) had strokes, including 167 (0.6%) of those without thyroid disease and 31 (1%) of those with thyroid disease.

After adjusting for known risk factors for stroke, including older age, blood pressure, diabetes, and history of atrial fibrillation, the researchers concluded that having an overactive thyroid was associated with a 44% increased risk for ischemic stroke, which is stroke cause by blocked arteries.

“This study is important because hyperthyroidism has not been considered a potential risk factor for stroke and there are up to a third of young ischemic stroke patients without a determined cause,” Lin says.

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