Premature pubarche as an indicator of how body weight influences the onset of adrenarche

Premature pubarche (PP) is defined as the development of pubic and/or axillary hair before the age of 8 years in girls and 9 years in boys. The objective was to obtain a clearer picture of the physiology of adrenarche by evaluating clinical-laboratory features of PP. The 216 consecutive children were classified according to their sex and age of onset of PP: PP occurred before 2 years in 21 girls and one boy, between 4 and 7.9 years in 162 girls and between 5 and 8.9 years in 28 boys. It occurred between 2 and 4 years in only four girls. The body mass index (BMI) was greater than or equal to+2 SD in 2 children aged <2 years (9.1%), in 52 girls aged >4 years (32.5%) and in 13 boys aged >5 years (46.4%). The plasma dehydroepiandrosterone sulphate (S-DHEA) concentrations in children aged <2 years were lower than those expected in Tanner stage 2. They were higher in obese girls >4 years than in lean ones (P=0.009), with a positive correlation between S-DHEA and BMI z-score (P=0.004). Birth weights of girls >4 years were lower than those of the general population (P<0.01). Conclusion:premature pubarche is rare in boys. The cause in children aged <2 years is probably different than in older ones. Premature pubarche is associated with low birth weight in girls. The frequency of obesity and the correlation between dehydroepiandrosterone sulphate levels and body mass index suggest that body weight is involved in the onset of adrenarche.