Thyroid dysfunction is associated with an increased risk of senescence, pointing to the need for a new approach toward healthcare for older adults, a new study has shown.

Professor Lee Jeong-min of the Department of Endocrinology at Catholic University of Korea Eunpyeong St. Mary's Hospital and her colleagues analyzed the association between thyroid function and frailty based on health and nutritional information and thyroid function tests of 2,416 men and women aged 50 and older from the Korea National Health and Nutrition Examination Survey (2013-2015).

Using the “Fried frailty phenotype" model, the researchers analyzed the data from the subjects and found an increased risk of frailty in populations with hyperthyroidism and subclinical hypothyroidism. The model assesses frailty based on five criteria -- unintentional weight loss, decreased muscle strength, fatigue, slow walking speed, and low physical activity.

In analyses that adjusted for various factors, including differences in the individual health status of the study subjects, the study found hyperthyroidism was also associated with frailty.

Specifically, higher levels of free thyroxine (FT4) in subjects with hyperthyroidism were more strongly associated with an increased risk of frailty. In hypothyroidism, low FT4 and high thyroid-stimulating hormone (TSH) levels were associated with frailty, whereas subclinical hypothyroidism was not associated with an increased risk of frailty.

Frailty is a condition in which the physiological ability of the body to maintain homeostasis is reduced by several factors, increasing the likelihood of a variety of conditions, resulting in increased dependence on others, the likelihood of hospitalization, and the risk of death. It differs from aging, an irreversible and inevitable process that occurs with age.

In recent studies, frailty has also been referred to as a geriatric syndrome, and because it involves a wide variety of causes, including generalized functional decline with age, comprehensive functional assessments are often performed to identify the causes. Various studies have shown that muscle strength decline is one of the biggest factors that increase the risk of frailty, making it an important indicator for preventive healthcare in older adults.

"This study is significant, as it revealed the link between thyroid function and frailty, providing new indicators and perspectives for the healthcare of the elderly population," Professor Lee said. "As the link between thyroid dysfunction and increased risk of frailty has been confirmed, more careful treatment of thyroid patients and efforts to prevent the disease are needed."

The study was published in the latest issue of Endocrinology and Metabolism, an international journal in the field of endocrinology, and won the Best Oral Presentation Award at the 11th Seoul International Congress of Endocrinology and Metabolism and the Fall Conference of the Korean Endocrine Society at Lotte Hotel in Seoul recently.