Normal levels of TSH affect the metabolic profile differently in physically active males and females

Abstract

Background Our study was aimed at the evaluation of relationships between thyroid stimulating hormone (TSH) within the normal range and metabolic risk factors (glucose, insulin, HOMA-IR and lipoprotein profile) in physically active male and female students. Methods In 112 male and 107 female students circulating TSH, glucose, insulin and lipoproteins (triacylglycerols, total cholesterol, HDL-cholesterol and LDL-cholesterol) were measured in blood under fasting conditions. Insulin resistance was expressed as HOMA-IR. For further procedures 99 males and 97 regularly menstruating females with TSH 0.4 – 4.0 µIU/ml were accepted. Results In male students no correlations between circulating TSH, anthropometric and biochemical variables were noted. In females TSH within the normal range was slightly but significantly correlated with the triglyceride (TG) level (p<0.03). However, step-wise multiple regression analysis revealed that the effect of TSH was small (p<0.046) in relation to that found for HOMA-IR (p<0.0009). No relationships between biochemical variables and normal levels of TSH were noted in male students. However, surprisingly normal range TSH in males was slightly but significantly correlated with the percentage of body fat and this issue needs further studies concerning measurements of different fat depots.Conclusions The above data suggests that in active females TG synthesis and export from the liver is more sensitive to TSH action than in active male counterparts.