Abstract W MP59: Thyroid Hormones And Functional Outcomes After Ischemic Stroke

Abstract

Background: Hypothyroidism can lead to hypertension, hypercholesterolemia, and cardiac dysfunction, which are risk factors for stroke. Activity of the hypothalamic-pituitary-thyroid axis may contribute to functional stroke outcomes. Low levels of thyroid stimulating hormone (TSH) correlate with an increased risk of ischemic stroke. However, once a stroke occurs, hypothyroidism is associated with more favorable outcomes. It is well known that thyroid hormone levels drop rapidly in critically ill patients (“sick-euthryoid” syndrome), which may be prevented by the exogenous thyroid replacement provided to hypothyroid patients. We directly assessed thyroid function with measurements of TSH, free T3 (fT3) and free T4 (fT4) in patients with ischemic stroke and evaluated acute and long-term outcomes. Methods: Blood was collected prospectively from patients with radiologically confirmed ischemic stroke (AIS) (n=136) 24 hours after symptom onset. Serum levels of TSH, fT4, and fT3 were quantified by ELISA. Primary outcomes were in-hospital mortality and admission NIH Stroke Scale (NIHSS). Secondary outcomes were admission to discharge change in NIHSS, modified Barthel Index (mBI) and modified Rankin score (mRs) at 3 and 12 months (mo), and mortality at 3 and 12 mo. Results: AIS patients show a negative correlation in fT3 with age (r=-.332, p<0.01 ). AIS patients with a higher pre-stroke mRS had higher levels of fT3, and fT4 , p=0.01, p=0.03 ). Patients that died or went to hospice had significantly lower levels of fT3 and TSH (1.99pg/ml (1.75-2.48), 0.52 pg/ml (0.30-0.76)).TSH levels were lower in AIS patients with worsened NIHSS (0.72 pg/ml (0.36-1.12)). Higher fT3 levels were significantly associated with better mRS and mBI at 3 and 12 mo ( p=0.01, p=0.01, p=0.03, p=0.02 ), whereas lower levels of TSH were significant for worse mRS at 3mo (0.87pg/ml (0.59-1.48)). Conclusion: While higher levels of fT3 correlate with stroke risk factors, high fT3 is seen in patients with better functional outcome at 3 and 12mo post-stroke. Ischemic stroke patients with low TSH levels at 24 hrs have higher mortality. Thus, monitoring the hypothalamus-pituitary-thyroid axis during acute stroke may improve long-term stroke outcomes.