Older hospital patients who have low thyroid hormone levels have a higher level of mortality, new study results show.

Researchers in Spain found that older individuals with a “reduced ability to synthesize T3 hormones have a higher rate of mortality, both in the short- and long-term,” said lead author Pedro Iglesias, M.D.

The study observed a group of more than 400 people older than 65 who were admitted to a hospital in Segovia, Spain, and tracked their survival rate over seven years.

Researchers found an association between low levels of thyroid hormones and mortality. The thyroid gland produces triiodothyronine (T3) and thyroxine (T4). 

While it is unclear why these seniors were more likely to die, Iglesias noted that T3 could be a useful measure to assess an older person’s chances of surviving an acute illness that required hospitalization.  

“The reduced ability to synthesize the hormone observed in this group of patients could be related to the severity of the disease and its prognosis,” he said. 

The study was scheduled to appear in the December edition of the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism.