Session: SAT 677-696-Obesity Physiology & Epidemiology
Poster Board SAT-692
Objective: This study aimed therefore to analyse serum testosterone and free testosterone concentration by using gold-standard techniques, i.e. liquid chromatography tandem mass and spectroscopy (LC-MS/MS) and equilibrium dialysis, in association with a detailed clinical assessment (Tanner stage and testisvolume) in obese male adolescents.
Methods: 51 male obese adolescents (mean BMI sds: + 2.55), aged 10-19y at start of a residential obesity treatment program and 51 age-matched healthy (mean BMI sds: -0.17) controls were studied. Pubertal status was assessed according to the method of Marshall and Tanner and testicular volume was measured using the Prader orchidometer by the same investigator. Testosterone (by LC-MS/MS), free testosterone (by equilibrium dialysis), LH and SHBG (by commercial immunoassays ) were measured.
Results: Compared to age-matched controls, there was no significant difference in genital staging (obese vs controls: G1: 12 vs 10 %; P2: 18 vs 16 %; P3:12 vs 16 %; P4: 33 vs 33 %; P5: 26 vs 26 %; NS) and mean (±SD) testicular volume (15 ± 8 ml vs 15 ± 8 ml; NS). While both testosterone (247 (35-355) vs. 407 (81.1-482) ng/l; p=0.05) and SHBG (2.5 (1.9-4.3) vs. 5.5 (4.0-8.9) nmol/l; p<0.001) concentrations were significantly lower in the obese group, free testosterone (5.6 (0.6-9.0) vs. 5.7 (0.7-9.1) ng/l; NS) and LH concentrations (3.6 (1.6-4.7) vs. 2.5 (1.6-4.4) mU/ml; NS)) were comparable between both groups. As expected, higher total and free testosterone levels were found with advancing pubertal development in both groups. Although obese adolescents had lower SHBG and testosterone levels at each pubertal stage, free testosterone levels were similar from Tanner stage G1 to G4.
Conclusion: Testosterone and SHBG concentrations but not the free testosterone concentration were lower in obese adolescents compared to age-matched controls, while they presented a normal and comparable testicular volume and pubertal development. Therefore, in adolescent obesity free testosterone concentration reflects better the Leydig cell function than total testosterone.
Nothing to Disclose: SV, YT, TF, IR, MV, PD, JD, JMK
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