Endocrine Abstracts

Introduction: The presence of glandular breast tissue in males around puberty, pubertal gynaecomastia, is a very common (40–60%) condition although the aetiology behind is poorly understood. It is generally accepted that pubertal gynaecomastia is caused by an excess of estrogens and/or a deficit of androgens. However, other hormones such as prolactin, GH and IGF1 may also affect ductal growth of the breast.

Design: A cross-sectional study of 518 healthy Danish school boys (aged 6.1–19.8 years) as a part of the COPENHAGEN Puberty Study. Anthropometry and pubertal stages (PH1–6 and G1–5) were evaluated, and the presence of gynaecomastia was assessed. Body fat percentage was calculated by means of skin folds and impedance. Non-fasting blood samples were analysed for FSH, LH, testosterone, SHBG, estradiol, IGF1, IGFBP3 and prolactin. Furthermore free-testosterone, FAI and E₂/testosterone were calculated.

Results: We found that boys with gynaecomastia had significantly higher height, weight, hip circumference, testis volume, genital- and pubic hair stages, levels of FSH, LH, estradiol, testosterone and IGF1, but lower levels of SHBG. FSH (P=0.029) and IGF1 (P=0.003) remained significantly higher in boys with gynaecomastia even after adjustment for age and pubertal stage. We did not find any significant difference in the sex steroid levels or in estradiol/testosterone-ratio, FAI, or free testosterone.

Conclusion: We found that Danish boys with gynaecomastia had significantly higher serum IGF1 levels compared to boys without palpable gynaecomastia at the time of investigation. No other significant hormonal differences were seen. We suggest that the GH–IGF1 axis may be involved in the pathogenesis of pubertal gynaecomastia.