Distinguishing central precocious puberty from nonprogressive breast development: adiposity and DXA body composition

Objective: Distinguishing central precocious or early puberty (CPP/EP) from nonprogressive premature breast development (npPBD) is challenging, particularly in the context of increasing childhood adiposity, which may affect growth and skeletal maturation independently of hypothalamic-pituitary-ovarian (HPO) axis activation. Methods: We retrospectively evaluated 100 girls (69 CPP/EP, 31 npPBD) and 16 age-matched prepubertal girls with obesity as controls. Assessments included auxology, bone age, hormonal and metabolic profiles, pelvic ultrasound, DXA-derived body composition, and lifestyle factors. Results: Anthropometric parameters and bone age were similar between CPP/EP and npPBD, whereas LH, FSH, estradiol, and IGF-1 SDS (all P < .001) remained the main discriminators between groups. Overall body composition was comparable, except for a higher android-to-gynoid fat ratio in npPBD (P = .03). In both diagnostic groups, overweight/obesity was associated with greater height relative to target height (P = .004 in CPP/EP; P = .03 in npPBD) and higher IGF-1 SDS (P < .001 and P = .02, respectively) compared with controls. Among normal-weight girls, those with CPP/EP showed greater height relative to target height (P = .009) and more advanced bone age (P = .02) than those with npPBD, whereas these differences were not observed in girls with overweight/obesity. Conclusion: Excess adiposity reduces the diagnostic specificity of auxological and skeletal maturation parameters in girls with early breast development. Biochemical assessment remains central, with IGF-1 SDS providing additional supportive information.