Endocrine Abstracts

The impact of BMI, exercise, smoking, drug and alcohol use on reproductive and thyroid hormones has little or conflicting evidence. We therefore aimed to investigate the association between these factors and serum hormone concentrations. Capillary blood samples were taken from 932 eumenorrheic Hertility Health users on menstrual cycle day 3 between Sept 2020 and June 2022. Serum concentrations of Anti-Müllerian hormone, Estradiol (E2), Luteinising Hormone (LH), Follicle-Stimulating Hormone, free Thyroxine, Thyroid-Stimulating Hormone (TSH) and Prolactin (Prl) were measured via chemiluminescence immunoassay. Women self-reported their height, weight, exercise frequency, weekly alcohol consumption, recreational drug use and smoking status. Women with PCOS or premature ovarian insufficiency were excluded from analysis. Following stratification into two age groups (18-30 and 31-40), data was log-transformed and the Pearson correlation coefficient (r) between pairs of variables was calculated; P values <0.05 were considered statistically significant. In 18-30 year olds, BMI negatively correlated with E2 (r=-0.13, P=0.02, n=308) and LH (r=-0.24, P<0.01, n=306) and positively correlated with TSH (r=0.12, P=0.04, n=292). Exercise frequency positively correlated with LH (r=0.16, P=0.02, n=201) and drug use negatively correlated with Prl (r=-0.2, P=0.02, n=151). In 31-40 year olds, BMI negatively correlated with E2 (r=-0.11, P<0.01, n=548), LH (r=-0.20, P<0.01, n=545) and Prl (r= -0.12, P=0.03, n=352). These data suggest BMI has a weak but significant negative association with reproductive hormones and a weak positive association with TSH. Exercise frequency and drug use have a small positive association with reproductive hormones, whilst alcohol consumption and smoking status did not appear to have a significant impact. Further investigation into these associations is necessary.