Age-related changes in adrenal size during the first year of life in normal newborns, infants and patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency: comparison of ultrasound and hormonal parameters.

An adrenal size index (ASI) was specifically designed to improve ultrasound evaluation of adrenal size in the 1st year of life. In 84 newborns and infants, ASI and plasma dehydroepiandrosterone sulphate (DHEA-S) concentrations were determined to study in vivo changes in adrenal size and cortical zonal composition. ASI was higher (P less than 0.0001) in the first 2 postnatal weeks (median 60.5 mm2) than in the rest of the first year (median 39.6 mm2) and showed a negative correlation with chronological age (r = -0.41). A positive correlation existed between DHEA-S concentrations and ASI (r = 0.29) as well as ASI relative to body weight (r = 0.57). These data and changes in gland echogenicity are consistent with histopathological observations that the early decrease in adrenal size is due to involution of the fetal zone. In four patients with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase (21-OHase) deficiency, ASI and plasma concentrations of pre-defect steroid were determined. Two patients with severe salt loss had markedly elevated ASI, which returned to normal during treatment. Two patients without severe salt loss had pretreatment ASI in the upper normal range, which decreased with treatment. Our findings indicate that ASI is useful in assessing physiological changes in adrenal size and, in conjunction with DHEA-S determinations, in adrenal cortex composition. ASI may aid in the early diagnosis of the salt-losing variety of 21-OHase deficiency. ASI is an instantaneously available tool which, in addition to biochemical and clinical data, can be used to monitor treatment of 21-OHase deficiency.