Clinical features suggestive of non-classical 21-hydroxylase deficiency in children presenting with precocious pubarche

: Precocious pubarche (PP) is defined as the onset of pubic hair at 8 years of age in girls and at 9 years of age in boys. PP is idiopathic (IPP) in most children, but it is the earliest manifestation of non-classical congenital adrenal hyperplasia owing to steroid 21-hydroxylase deficiency (NC21OHD) in 5%-20% of cases. 17-Hydroxyprogesterone (17OHP) levels after ACTH stimulation test are used to distinguish the two forms. We studied clinical indicators of NC21OHD in 289 PP children: 14 (4.8%) showed post-ACTH 17OHP levels >30 nmol/L and NC21OHD due to CYP21A2 gene mutations was confirmed. NC21OHD children were younger (p: 0.006) and thinner (p: 0.003) than IPP children. Height standard deviation score (SDS) was not different (p: 0.97). NC21OHD girls showed more advanced bone age than IPP girls (p<0.001). Earlier PP onset and bone age advance suggest NC21OHD, which requires confirmation by an ACTH stimulation test. Later, PP appearance in overweight children suggests IPP and could merit only clinical monitoring.