(O-20) Inter- and Intraindividual SHBG variation and its impact on hormonal clustering in men with sexual dysfunction

Introduction Hypogonadism diagnosis requires both clinical symptoms and at least 2 low total testosterone (TT; ng/dL). However, testosterone bioavailability also depends on sex hormone binding globulin (SHBG; nmol/L), influenced by age, BMI, and comorbidities. This study evaluated SHBG variation between men with different hormonal profiles and between serial measurements in the same patient. Methods A retrospective cohort of 96 men from a tertiary center with sexual dysfunction requiring surgical treatment. Inclusion required two complete hormonal panels: TT, calculated free testosterone (cFT; pmol/mL), SHBG, luteinizing hormone (LH; IU/L), FSH, estradiol. cFT was calculated using TT and SHBG. SHBG was compared across hormonal clusters (A–E) and between first and second measurements in each patient. SHBG values of 80 patients in a control group of vasectomized men without sexual symptoms was also analyzed. Results Patients with sexual dysfunction (median age 67.5) showed wide SHBG values (6–110.5 nmol/L). Controls (median age 39) also showed high variability (9.5–108.8). SHBG varied up to 20-fold across individuals. Intraindividual stability was moderate: 72.6% remained in the same SHBG tercile between tests, but 40.6% changed hormonal clusters. Conclusion SHBG shows wide inter- and intraindividual variability, potentially altering hormonal classification and impacting hypogonadism diagnosis and treatment decisions. Financing No conflict.