We report an infant female with salt wasting form of CAH due to 21 hydroxylase deficiency, who had onset of vaginal bleeding at 3 months of age(day 88 of life). Adrenal steroid suppression was achieved by 2½ weeks of age. At the time of bleeding, imaging studies revealed an enlarged right ovary with a dominant 3×3×3 cm cyst and additional small <1 cm cysts (not seen on newborn sonogram). The uterus was enlarged and stimulated. 3 weeks later (day 109, 1 wk after cessation of bleeding) ultrasound demonstrated a marked decrease in the size of the right ovary and the dominant cyst was no longer seen. The hormonal data and response to GnRH (100 ug/m2) are shown below and demonstrate elevated E2 levels at about 3 mo of age, and a heightened FSH response. Previous reports have shown that female infants with CAH maintain the sexual dimorphic pituitary response to GnRH despite in-utero exposure to androgens. This is true in our infant who, at the time of bleeding, had a predominantly FSH response to GnRH, mimicking the normal neonatal female pattern. Despite reports in older children with CAH that a rapid suppression of adrenal steroids can be associated with the onset of true precocious puberty, our patient's hormonal data are not consistent with this observation. We believe that the decline in adrenal adrogens following glucocorticoid treatment resulted in an increase in gonadotropin levels that then triggered a transient and augmented, albeit non-sustained, end-organ response. Further, our infant's hormonal findings likely reflect a delay in the development of “negative” restraint by sex steroids on gonadotropins. Table

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