People with higher levels of thyroid hormone in their bloodstream may be at greater risk of sudden cardiac death, even if those levels aren’t abnormally high, a new study suggests.
“Our study shows that the risk of sudden cardiac death increases with higher thyroid hormone levels, even in the normal range,” said lead researcher Dr. Layal Chaker, a research fellow in endocrinology and epidemiology at Erasmus University Medical Center Rotterdam in the Netherlands.
Sudden cardiac death occurs when a person’s heart stops due to a malfunction in the electrical system that derives the heartbeat.
Researchers found that people with thyroid hormone levels at the high end of the normal range were 2.5 times more likely to die from sudden cardiac death, compared with people at the lower end of the range.
In addition, the 10-year risk of sudden cardiac death was four times greater among people with high levels of thyroid hormone, according to the report.
This potential connection between high-normal thyroid hormone levels and sudden cardiac death is “really new, in that we really never made this association in the past,” said Dr. Vincent Bufalino, an American Heart Association spokesman and cardiologist in Naperville, Ill.
“We do know that thyroid hormone in excess sort of speeds up the heart,” Bufalino said. “Your metabolism is faster, higher. Your engine is running hot, so to speak,” he said.
But negative effects on heart health have mainly been associated with “toxic” levels of thyroid hormone that are far above normal levels, he said.
More than half of all heart-related deaths stem from sudden cardiac death. Most of the time victims had no previous symptoms of heart disease, the authors said in background notes.
Thyroid hormone helps regulate how the body converts food into energy, and plays an essential role in the function of the major organs, the study authors said.
For this study, Chaker and her colleagues analyzed more than 10,000 patients in the Rotterdam Study, a long-term investigation of chronic disease among the middle-aged and elderly in the Netherlands.
The new report appears Sept. 6 in the journal Circulation.
This study looked at T3 and T4 (thyroid hormone) levels. Currently, most physicians use the TSH (thyroid stimulating hormone), which is actually a pituitary hormone, as the gold standard to evaluate thyroid function.
Hopefully, this study will prompt physicians to take a closer look at the thyroid, including a full thyroid profile. Those tests include a TSH, T3, T4, TPO (thyroid peroxidase), thyroid auto-antibodies, and a reverse T3.
The relationship between a high normal TSH, cardiovascular disease, and diabetes has been long established. However, this is the first study to indicate a link between high normal thyroid hormones and cardio-electric health. I suspect similar links will be found between these hormone levels, tachycardia, and AF atrial fibrillation).
The Bottom Line:
Please ask your PCP (primary care physician) to run a complete thyroid profile on your yearly physical. Don’t accept the “everything looks good” evaluation, compare your results with healthy norms rather than the traditional medical norms.
Source: September 6, 2016 National Institutes of Health