OBJECTIVETo investigate the characteristics of sexual development and sex hormone levels in obese male adolescents.

METHODSWe included 156 obese male adolescents with micropenis and microorchidia in an observation group and 50 healthy ones in a control group. We measured the body mass index (BMI), penile natural length and testicular volume, investigated the incidence of spermatorrhea and the age of the first spermatorrhea, detected the levels of serum luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin (PRL), total testosterone (TT), free testosterone (FT), progesterone (P) and estradiol (E2) using radioimmunoassay, and calculated TT/E2 and testosterone secretion index (TSI).

RESULTSCompared with the healthy controls, the obese adolescents showed significantly higher BMI ([20.4 +/- 1.6] vs [27.1 +/- 2.2] kg/m2, P < 0.05), but shorter penile natural length ([6.7 +/- 2.1] vs [5.6 +/- 1.7] cm, P < 0.05) and lower testis volume ([9.9 +/- 3.1] vs [7.6 +/- 2.3] cm3, P < 0.05). The incidence of spermatorrhea was significantly decreased in the observation group in comparison with that of the control (chi2 = 17.335, P < 0.05), but there was no significant difference in the age of the first spermatorrhea between the two groups (P > 0.05). The levels of LH, E2 and P were remarkably higher in the observation group than in the control ([7.82 +/- 2.14] vs [5.39 +/- 1.76] mIU/ml, P < 0.05; [48.57 +/- 8.34] vs [8.61 +/- 4.08] pg/ml, P < 0.01; and [1.25 +/- 0.58] vs [0.64 +/- 0.19] ng/ml, P < 0.05), while TT and FT were markedly lower in the former than in the latter ([0.73 +/- 0.20] vs [1.47 +/- 0.41] ng/ml, P < 0.01 and [5.09 +/- 2.60] vs [11.28 +/- 4.72] pg/ml, P < 0.01), and so were the TT/E2 ratio and TSI (0.015 +/- 0.004 vs 0.173 +/- 0.037 and 0.098 +/- 0.026 vs 0.272 +/- 0.084, P < 0.01). BMI was correlated positively to PRL and E2, but negatively to TT, FT, TT/E2 and TSI (P < 0.05); the penile natural length positively to TT, FT, TT/E2 and TSI, but negatively to E2 (P < 0.05); and the mean testis volume positively to TT, FT, TT/E2 and TSI, but negatively to LH, PRL and E2 (P < 0.05).

CONCLUSIONTestis dysplasia and alteration of sex hormone levels exist in obese male adolescents. Obesity and fat accumulation lead to increased E2 and decreased TT and FT, particularly the reduction of TT/E2 and TSI, which suggest that the body fat content has an important influence on the development of the male reproductive system.