Effect of sub-clinical hypothyroidism on clinical severity in first-ever acute ischemic stroke.

Background: Subclinical hypothyroidism has been documented to have a positive effect on the clinical presentation and outcome in acute ischemic stroke.Objective: To determine the prevalence of subclinical hypothyroidism in first ever ischemic strokes and to evaluate its effect on the clinical presentation.Methods: Using a cross-sectional study design, 138 patients diagnosed with first ever ischemic stroke within 7 days of onset were included in the study. Each participant had documentation of demographic data, followed by a detailed neurological examination. Stroke severity on admission was recorded using the National Institute of Health Stroke Scale (NIHSS) and blood samples for free thyroxine (T4) and thyroid stimulating hormone (TSH) were taken within 24h of onset of symptoms. For analysis, the patients were divided into two groups: those who had elevated TSH level (> 2.5mIU/L) with normal FT4 level were assigned to the sub-clinical hypothyroidism group whilst those with normal thyroid function were assigned to the control group. All values were compared between the two groups.Results: The study population comprised of a total number of 138 participants with mean age of 63.4 ± 12.9 years. The females were 56 (40.6%) and the males were 82 (59.4%). A total number of 11(7.9%) had subclinical hypothyroidism whilst 127 participants (92%) had normal thyroid functions. The mean NIHSS score of cases with SCH on admission was significantly lower than that of those with normal thyroid functions (6.73± 3.6 vs 11.1 ± 6.3, p=0.025). A significantly higher proportion of patients in the SCH group had mild neurologic deficits on admission compared with the group with normal thyroid functions (81.8% vs 24.4%, p < 0.001).Conclusion: Our study has suggested that subclinical hypothyroidism appears to confer a neuroprotective effect in acute ischemic stroke.Key words: Subclinical hypothyroidism, acute ischemic stroke, NIHSS, clinical severity