Scientists aren’t sure why, but higher levels of thyroid hormone in the blood has been shown to increase an individual’s risk for sudden cardiac death. This discovery comes from a recent study from the American Heart Association (AHA).
“Identifying additional risk factors is crucial,” said Layal Chaker, MD, MSc, lead study author, referring to sudden cardiac death. A 2012 Circulation study showed that over 50 percent of all cardiovascular deaths arise from a sudden loss of heart function. Alarmingly, many people who die from a sudden loss of cardiac function have no previous symptoms of heart disease.
Although the reasons aren’t yet clear, high thyroid levels could be a new factor to predict the unpredictable. Scientists from the AHA analyzed over ten thousand patients from The Rotterdam Study to learn more.
During an average Rotterdam Study follow-up of nine years, researchers looked at the association of thyroid-stimulating hormone and free thyroxine thyroid hormone levels in blood samples with “sudden cardiac death” listed on medical records and death certificates. What they found was consistent with their thoughts on the thyroid hormone:
“Participants with free thyroxine hormone levels at the high end of the normal range were 2.5 times more likely to die of sudden cardiac death, compared to patients with levels at the lower end.”
The elevated risk for sudden cardiac death was not affected, even after controlling for other variables such as high blood cholesterol and hypertension.
Chaker and his team are still unsure how high levels of thyroid hormone in the blood is causing sudden cardiac death in some patients, but for now they believe it to be a dependable risk factor. Chaker believes that patients on thyroid hormone replacement therapy are often over-treated, leaving them with abnormally high blood levels of thyroid hormone.
The thyroid hormone is found in the bloodstream, and it helps regulate a majority of the body’s organs, the heart included. While a link between heart disease and thyroid hormone is already established, scientists still don’t have a complete understanding of how the thyroid hormone ties back to sudden cardiac death.
The present study was published in the journal Circulation
Source: American Heart Association