Low Free Triiodothyronine Should Be Associated With 3-Month Poor Functional Outcome After Acute Stroke

Objectives: Thyroid dysfunction has been associated with increased short-term mortality during intensive care unit stay, and with long-term mortality in cardiovascular disease. However, the association between thyroid function and clinical characteristics in patients with acute stroke has not yet been thoroughly studied. The purpose of the present study was to test the hypothesis that thyroid hormone is associated with three-month functional outcome after acute stroke. Methods: We retrospectively analyzed 908 consecutive patients with acute stroke (578 men and 330 women; median age: 73 years) who were admitted to our department between September 2014 and November 2016. General blood tests including thyroid stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4), were performed on admission. Neurological severity was evaluated using the National Institutes of Health Stroke Scale (NIHSS) score on admission and modified Rankin Scale (mRS) score at three months after stroke onset. Poor outcome was defined as a modified Rankin Scale (mRS) score of 3-5, or death (mRS score of 6). The impact of thyroid function on three-month outcome was evaluated using multiple logistic regression analysis. Results: Poor functional outcome was observed in 384 patients (42.2 %). Age ( P < 0.0001), female gender ( P < 0.0001), the presence of diabetes mellitus ( P = 0.0151), high admission NIHSS score ( P < 0.0001), smoking ( P = 0.0064), atrial fibrillation ( P < 0.0001), high pre-admission mRS score ( P < 0.0001), low estimated glomerular filtration rate ( P = 0.0026) and ischemic heart disease ( P = 0.0061) were significantly associated with poor functional outcome, but no relationships between FT4, TSH and poor functional outcome were found. After adjusting for age, sex, stroke severity, and various comorbidities, lower FT3 values was independently associated with poor functional outcome (odds ratio [OR], 1.60; 95% confidence interval [CI], 1.27-2.03) and mortality (OR, 2.19; 95% CI, 1.58-3.07) at three months after stroke onset. Conclusions: Our data suggest that a lower FT3 value upon admission should be considered to have an association with three-month poor functional outcome and mortality in patients with acute stroke.