Ischemic Stroke and Impact of Thyroid Profile at Presentation: A Systematic Review and Meta-analysis of Observational Studies.

BACKGROUND: Stroke is the fifth leading cause of mortality in the United States and a leading cause of disability. A complex relationship between thyroid hormone levels and severity of, and outcome after, stroke has been described. AIM: Our objective is to identify the association between baseline thyroid function profile and outcome after acute ischemic stroke. METHODS: Studies looking at the association between thyroid function and functional stroke outcomes were identified from available electronic databases from inception to December 16, 2016. Study-specific risk ratios were extracted and combined with a random effects model meta-analysis. RESULTS: In the analysis of 12 studies with 5218 patients, we found that subclinical hypothyroidism was associated with better modified Rankin scale scores at 1 and 3 months (odds ratio [OR] 2.58, 95% confidence interval [CI] 1.13-5.91, P = .03 and OR 2.28, 95% CI 1.13-3.91, P = .003, respectively) compared with the euthyroid cases. Likewise, patients with higher initial thyrotropin-releasing hormone (TSH) and fT3 or T3 levels had favorable outcomes at discharge (mean differences of TSH .12 [95% CI .03-.22, P = .009] and of fT3 .36 (CI .20-.53, P < .0001]) and at 3 months (mean differences of TSH .25 [95% CI .03-.47, P = .03] and of T3 8.60 [CI 4.58-12.61, P < .0001]). CONCLUSIONS: Elevated initial TSH (clinical or subclinical hypothyroidism) may correspond to better functional outcomes, whereas low initial T3/fT3 might correlate with worse outcomes in acute ischemic stroke among clinically euthyroid patients. This complex relation merits further well-designed investigations. Whether correcting thyroid profile with hormone supplementation or antagonism may lead to improved outcomes will require large, prospective, interventional studies.