Postnatal Changes in Adrenal Size in Very Low-Birth-Weight Infants: Sonographic Evaluation for the Prediction of Late-Onset Glucocorticoid-Responsive Circulatory Collapse

We investigated the postnatal pattern of changes in adrenal size in very low-birth-weight (VLBW) infants and its relation to late-onset glucocorticoid-responsive circulatory collapse (LGCC) that may be associated with adrenal insufficiency. In 36 VLBW infants born at <33 weeks' gestation, ultrasound examinations of postnatal changes in adrenal size during the first 3 weeks of life were performed. VLBW infants were classified into three groups: group A (n = 6), the actual adrenal area was greater than or equal to the predicted value at birth and unchanged at 3 weeks; group B (n = 24), the actual adrenal area was greater than or equal to the predicted value and decreased at 3 weeks; and group C (n = 6), the actual adrenal area was less than the predicted value and unchanged at 3 weeks. Five infants developed LGCC, and all five were in group A. These observations suggest that the life of the adrenal fetal zone might be extended beyond 3 weeks after birth in some VLBW infants and that prolonged fetal zone activity might correlate with LGCC. On the other hand, adrenal maturation might have already occurred at birth in some VLBW infants. Sonographic evaluation of adrenal size may enable prediction of subsequent LGCC in VLBW infants.