The Role of Inflammation in Contributing to Vascular Risk in Subclinical Hyperthyroidism: Randomized Controlled Trial

Background: Subclinical hyperthyroidism (SH, defined by low or undetectable serum thyroid stimulating hormone and normal thyroid hormones) is associated with increased cardiovascular risk (CVR) such as atrial fibrillation. Few studies also showed an increased risk of vascular disease and mortality in SH. Inflammation has been shown to play a significant role in the pathogenesis of cardiovascular disease. Increased levels of C-reactive protein (CRP), lipoprotein associated phospholipase A2 (Lp-PLA2, an inflammatory marker which plays a critical role in atherosclerosis), neutrophil to lymphocyte ratio (NLR) and monocyte to lymphocyte ratio (MLR) have been reported in conditions with increased cardiovascular risk. We aimed to ascertain whether abnormal CRP, Lp-PLA2, NLR and MLR contribute to an increased CVR in SH. Methods: CRP, Lp-PLA2, NLR and MLR in peripheral blood were measured in 30 SH subjects at baseline and after 6 months of treatment with either carbimazole or placebo in a randomized placebo-controlled design. Results: There was no significant difference in CRP, Lp-PLA2, NLR and MLR between carbimazole and placebo treated groups at 6 months. There was also no statistical difference in the above parameters if we compared the change or difference between two visits (visit 2 and visit 0 levels) in both groups. Conclusion: There is no evidence of chronic inflammation in our small cohort of SH subjects. Our finding needs to be confirmed in future studies with larger number of SH subjects. J Endocrinol Metab. 2021;11(1):28-32 doi: https://doi.org/10.14740/jem723