Reinehr T, et al. - Boys with gynecomastia were compared with those with pseudogynecomastia (separation by ultrasound) regarding measures of sex hormones, IGF-1 and IGFBP-3. Researchers assessed 124 pubertal boys (mean age 14 ±2 years) with breast enlargement (86 boys suffering from gynecomastia and 38 from pseudogynecomastia) and 84 healthy boys (mean age 14 ±2 years) without breast enlargement in this observational study. Relative to boys with pseudogynecomastia or healthy controls without breast enlargement, boys with gynecomastia exhibited significantly higher the estradiol [E2]/testosterone [T] ratio even after adjustment for testes volumes and had significantly lower T concentrations. These findings suggest that a relative T deficiency to E2 concentrations characterize true gynecomastia in contrast to pseudogynecomastia.