Free triiodothyronine is associated with poor outcome after acute ischemic stroke

Abstract

Aims It is unclear whether thyroid hormones are associated with functional outcome after ischemic stroke. We aimed to investigate the impact of thyroid hormones at admission on functional outcome at 3 months after acute ischemic stroke. Methods A total of 480 consecutive patients for ischemic stroke within 48 hours of onset were enrolled in this study. Thyroid hormones including thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) were measured at admission and functional outcomes were assessed at 3 months with the modified Rankin Scale (mRS) ranging from 0 to 6. Poor outcome was defined as mRS≥3. Results FT3 levels at admission were considerably lower in poor outcome patients than those with good outcome at 3 months (3.53±0.70pmol/L vs 4.04±0.68pmol/L, respectively; P＜0.001). Lower levels of FT3 were observed with higher mRS scores. Multivariable logistic regression analysis revealed that FT3 levels were significantly associated with risk of poor outcome at 3 months independent of conventional risk factors such as age, NIHSS score and recanalized therapy. In addition, patients in the bottom quartile of FT3 levels had a 2.56-fold higher risk of developing poor outcome compared with patients in the top quartile (OR=2.56; 95%CI 1.15-5.69, p =0.021). The sensitivity and specificity of FT3 (≤3.69pmol/L) predicting poor outcome were 62.70% and 72.03% respectively. Conclusion Our study suggests that FT3 levels at admission are significantly and independently associated with risk of poor outcome after ischemic stroke and lower FT3 levels can be regarded as a prognostic biomarker for poor outcome at 3 months.