Cardiovascular Risk Determinants in Euthyroid Patients with Obesity: The Strange Case of TSH in Primary Prevention

Background: Thyrotropin (TSH), even in the normal range, is associated with components of cardiometabolic syndrome. We aimed to assess the relation between TSH and cardiovascular (CV) risk in euthyroid patients with overweight/obesity without previous cardiac events. Methods: A total of 1588 subjects (1132 females, mean age 53 ± 14 years) were recruited. This was an observational study. TSH, body mass index, waist circumference (WC), creatinine, hepatic enzymes, homocysteine, C reactive protein, glycated hemoglobin, homeostatic model assessment for insulin resistance (HOMA-IR), basal and 2 h glucose and insulin, fibrinogen, uric acid, a complete blood count, a complete lipid profile, and blood pressure were measured in all subjects. The Atherosclerotic Cardiovascular Disease (ASCVD) risk score was calculated. Results: More severe degrees of obesity were associated with higher TSH quartiles; specifically, 33% of subjects with grade III obesity had TSH in the 75th percentile. Multiple regression showed that female gender (t-value 3.6, p < 0.001), HOMA-IR (1.9, ≤0.05) and aspartate transaminase (AST; 2.8, <0.01) represent independent determinant factors affecting TSH levels in the population at higher CV risk (intermediate-high ASCVD risk score > 7.5%; n = 709). Similarly, TSH determinants in subjects with central obesity (n = 1197, WC >102 cm males, >88 cm females) were female gender (2.2, <0.05), HOMA-IR (2.7, <0.01) and smoking habit (-2.3, <0.5). Moreover, there was no significant relationship between TSH and ASCVD risk score. Conclusions: Higher TSH levels in the euthyroid range are related to high degrees of obesity and some CV risk factors, in subjects at higher cardiometabolic risk; however, for the different weight and sign of CV determinants (e.g., smoking habit) on the TSH system, the ASCVD risk score cannot evidence this relationship.