Overactive Thyroid May Raise Early Stroke Risk
44% Increase Seen in Younger Thyroid Patients
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
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
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
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
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.
Reducing the Risk of Stroke
Lin adds that more research is needed to confirm the association.
In the meantime, he says young adults with hyperthyroidism should be
vigilant about monitoring their thyroid status and they should do all they can
to reduce their modifiable risk factors for heart attack and stroke, such
as maintaining a healthy weight, remaining active, and avoiding smoking.
While Lin and colleagues suggest that young stroke patients be routinely
tested for hyperthyroidism, Wayne State University assistant professor of
neurology Brian Silver, MD, says the recommendation may be premature.
Silver is a spokesman for the American Heart Association.
“At this point, we don’t know if treating the thyroid would have any impact
on stroke risk,” he tells WebMD. “What we do know is that strokes are becoming
more common among young adults and we believe this is mainly due to increases
in obesity, hypertension, and diabetes. For young patients, the
critical thing would be to address these established risk factors.”