Longitudinal study of plasma testosterone in male pseudohermaphrodites during early infancy.

Plasma testosterone was longitudinally studied during the first months of life in 7 XY infants with male pseudohermaphroditism. In two, the physiological postnatal rise of plasma testosterone was absent or blunted. A combined adrenal and testicular enzymatic defect was demonstrated in these two boys. In 5, a normal postnatal testosterone rise demonstrated a normal Leydig cell function. The longitudinal study of the physiologic postnatal rise of testosterone may be useful to distinguish secretory defects from responsiveness abnormalities thus improving the choice of gender in male pseudohermaphrodites.