Objectives: Thyroid dysfunction has been associated with increased short-term mortality in intensive care unit and long-term mortality in cardiovascular disease. However, the association between thyroid function and clinical characteristics in patients with acute ischemic stroke has not yet been thoroughly studied. The purpose of the present study was to test the hypothesis that thyroid hormone is associated with functional outcome after acute ischemic stroke.
Methods: We enrolled 398 consecutive patients admitted to our stroke center from July 2010 to April 2012. General blood test including thyroid stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4), were performed on admission. Neurological severity was evaluated using National Institutes of Health Stroke Scale (NIHSS) scores on admission and modified Rankin Scale (mRS) scores on discharge. A poor outcome was defined as mRS score of 3-5 or death (mRS score 6). The impact of thyroid function on discharge outcome was evaluated using multiple logistic regression analysis.
Results: Discharge poor functional outcome was observed in 165 patients (40.3 %). Age (P = 0.0025), male gender (P = 0.0301), admission blood glucose level (P < 0.0001), admission NIHSS score (P < 0.0001), smoking (P = 0.0077), dyslipidemia (P = 0.0254), and arterial fibrillation (P < 0.0001) were significantly associated with poor functional outcome, but no relationship between FT4, TSH and poor functional outcome were found. On multivariable logistic regression analysis showed that poor functional outcome were independently associated with high blood glucose on admission (≧ 124 mg/dl; odds ratio [OR], 3.05; 95% confidence interval [CI], 1.74-5.46; P < 0.0001), old age (≥80 years; OR, 4.12; 95% CI, 2.22-7.82; P < 0.0001), high NIHSS score (≧ 7; OR, 14.64; 95% CI, 7.73-29.06; P < 0.0001), prior stroke (OR, 1.89; 95% CI, 1.01-3.55; P = 0.0448), and low FT3 (≦ 2.29 pg/ml; odds ratio [OR], 2.70; 95% confidence interval [CI], 1.50-4.88; P = 0.0009).
Conclusions: These findings suggest that low FT3 on admission may predict a poor discharge outcome in acute ischemic stroke. Further researches are needed to assess the impact of thyroid hormone as a potential marker for long term prognosis.