Correlations of serum level of thyroid-stimulating hormone with tumor necrosis factor-α, lipoprotein associated phospholipase A2 and interleukine-6 levels in ischemic stroke patients with subclinical hypothyroidism

Abstract

Objective To evaluate the correlations of serum level of thyroid-stimulating hormone (TSH) with levels of inflammatory factors lipoprotein associated phospholipase A2 (Lp-PLA2), tumor necrosis factor-α (TNF-α) and interleukine (IL)-6 in ischemic stroke (IS) patients with subclinical hypothyroidism (SCH) and its clinical significance. Methods Twenty SCH patients, 30 IS patients and 30 IS+SCH patients, admitted to our hospital from October 2017 to October 2018, were enrolled in our study; 27 subjects underwent physical examination in our hospital at the same period were selected as the control group. The serum levels of TSH, Lp-PLA2, TNF-α and IL-6 were measured by up-converting phoshor assay and enzyme - linked immunosorbent assay with double antibody sandwich. The common carotid artery, internal carotid artery and vertebral artery were examined by Doppler ultrasonography to analyze the morphology, location, and echo characteristics of the plaques and stenosis rates. Pearson correlation analysis was used to analyze the correlations of TSH with inflammatory factors, carotid artery stenosis rate. Results The levels of Lp-PLA2, TNF-α and IL-6 in IS+SCH group were significantly higher than those in SCH group, IS group and control group (P<0.05); those in the SCH group and IS group were significantly higher than those in the control group (P<0.05). The serum TSH levels in IS+SCH group and SCH group were positively correlated with Lp-PLA2 level (r=0.739, P=0.000; r= 0.697, P=0.000), TNF-α level (r=0.981, P=0.000; r=0.723, P=0.000) and IL-6 level (r=0.859, P=0.000; r=0.583, P=0.000); but the serum TSH levels in IS group and NC group were not correlated with Lp-PLA2 level (r=0.223, P=0.236; r=0.249, P=0.210), TNF-α level (r=0.304, P=0.103; r=0.056, P=0.780) and IL-6 level (r=0.027, P=0.887; r=0.138, P=0.491). The number of unstable plaques and degree of stenosis in IS+SCH group were larger/higher than those in IS group, SCH group and control group (P< 0.05); there was a positive correlation between serum TSH level and artery stenosis rate (r=0.739, P= 0.000). Conclusion SCH may lead to occurrence and development of atherosclerosis by increasing the serum levels of TNF-α, Lp-PLA2 and IL-6 caused by low-level chronic inflammation, which in turn increases the risk of ischemic stroke. Key words: Ischemic stroke; Subclinical hypothyroidism; Thyroid-stimulating hormone; Lipoprotein associated phospholipase A2; Tumor necrosis factor-α; Interleukin-6