While older adults with hypothyroidism face an elevated risk of death, individuals with subclinical hypothyroidism, a milder form of underactive thyroid, did not face the same risk, according to new research published in the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism.

Hypothyroidism occurs when the body produces too little thyroid hormone. Thyroid hormone controls a person’s metabolism and affects the way the body uses energy, consumes oxygen and regulates temperature. The condition occurs more often in women and people over the age of 60.

“Our meta-analysis is the first to evaluate and confirm the association between hypothyroidism and mortality, specifically focusing on an older population,” said Carol Chiung-Hui Peng, MD, of the University of Maryland Medical Center Midtown Campus in Baltimore, MD, and one of the study’s authors.

“Our analysis found individuals with hypothyroidism aged 60 years or older were 26% more likely to die from all causes than individuals in the same age range who did not have the thyroid condition,” said co-author, Huei-Kai Huang, MD, of Hualien Tzu Chi Hospital and Tzu Chi University in Hualien, Taiwan.

The researchers reviewed the results of 27 published articles including over 1.1 million older individuals. Although hypothyroidism was associated with all-cause mortality risk, the studies did not find a higher incidence of cardiovascular mortality. Interestingly, studies published in Asia and North America were associated with increased all-cause mortality in the hypothyroid population, while those published in Europe and Oceania were not. Among individuals with hypothyroidism who were 80 years old or older, the researchers found no increased risk of all-cause or cardiovascular mortality.

The mortality difference was not seen in older patients with milder forms of thyroid disease. This study provides further evidence to help guide management of hypothyroidism in older adults.

“In accordance with guidelines, our findings imply that individuals with subclinical hypothyroidism—those who have milder thyroid dysfunction—may not benefit from being treated with synthetic thyroid hormone,” said Kashif M. Munir, MD, associate professor in the division of endocrinology, diabetes and nutrition at the University of Maryland School of Medicine in Baltimore, MD, and another of the study’s authors. “However, treatment should be considered in individuals diagnosed with hypothyroidism, given increased all-cause mortality.”