Low triiodothyronine syndrome and depression: a cross-sectional study in the elderly based on comprehensive geriatric assessment.

Introduction: Thyroid diseases such as low triiodothyronine syndrome (LT3S) are more common in the elderly population. Comprehensive geriatric assessment (CGA) has been proposed as a supplementary tool for evaluating medical, functional, psychological, and frailty status and various geriatric syndromes. This study aimed to evaluate the impact of thyroid diseases on overall health status using a novel CGA strategy.

Material and methods: 477 patients were enrolled between January 2019 and December 2022. A structured CGA was conducted by a multidisciplinary team to identify older high-risk patients. Multivariate regression was performed to assess independent factors associated with thyroid status and CGA.

Results: The prevalence of abnormal thyroid hormone levels in the elderly was 34.2%. LT3S and anti-thyroglobulin antibody (anti-TgAb)-positivity or anti-thyroid peroxidase antibody (anti-TPOAb)-positivity were the main manifestations of thyroid diseases in elderly patients. The patients with LT3S had a higher prevalence of diabetes (p = 0.023), were older (p = 0.000), more often female (p = 0.014), with higher C-reactive protein (p = 0.001), and with lower body mass index (BMI) (p = 0.002), albumin (Alb) (p = 0.000), and haemoglobin (Hb) (p = 0.000) than patients with normal thyroid function. The CGA results showed higher rates of malnutrition and depression in patients with LT3S. Further multivariate logistic regression analysis showed that Hb [odds ratio (OR): 0.975; 95% confidence interval (CI): 0.959-0.990; p = 0.002] and LT3S (OR: 2.213; 95% CI: 1.048-4.672; p = 0.037) were independently associated with depression. Female (OR: 0.393; 95% CI: 0.160-0.968; p = 0.042), Alb (OR: 0.892; 95% CI: 0.811-0.981; p = 0.018), Hb (OR, 0.964; 95% CI: 0.939-0.989; p = 0.006), and LT3S (OR: 3.749; 95% CI: 1.474-9.536; p = 0.006) were independently associated with malnutrition.

Conclusions: LT3S was closely related to depression and malnutrition. Physicians should be more concerned about elderly patients with LT3S for their physical and mental status. Regular thyroid function checks might help to detect depression earlier.