Background: Prenatal androgen exposure can lead to variable virilization of external female genitalia. The lack of a consensus definition of clitoromegaly and the limited data available on normal steroid levels in female neonates makes its diagnosis difficult.
Objective and hypotheses: The aims of this study were (i) to define reference sizes for external female genitalia in term and preterm neonates as a function of gestational age and birth weight; and (ii) to determine reference values for steroid hormones in female neonate serum.
Method: We measured the clitoris (length, width) and the anogenital ratio for three-day-old female neonates born at a gestational age of 24 to 42 weeks. For neonates born after 35 gestational weeks the concentrations of nine steroids were analyzed by LC/MSMS, the main ones being testosterone (Testo), delta4 androstenedione (Delta4), 17-hydroxyprogesterone (17OHP), dihydroepiandrostenedione (DHEA), and dihydrotestosterone (DHT).
Results: For the 452 full-term female neonates included, the mean clitoris length is 3.6 mm (P95=6 mm), the mean clitoral width is 4 mm (P95=7 mm), and the mean anogenital ratio is 0.45 (P95=0.58). Preterm neonates are still being included. The normal values in nmol/l for the main steroids are as follows:
Conclusion: These results suggest (i) a definition of clitoridomegaly in full term neonates as a clitoris longer than 6 mm; (ii) an anogenital ratio greater than 0.6 is an indicator of possible in utero virilization. A set of reliable LC/MSMS-based reference values for steroid concentrations in female neonates are proposed.
10 - 12 Sep 2016
European Society for Paediatric Endocrinology