Antenatal betamethasone and renal ammoniagenesis in the newborn

As part of a double-blind clinical trial of antenatal betamethasone, we studied the effects of this drug on urinary ammonia excretion in 28 premature infants. Betamethasone was administered before 34 weeks of gestation according to dosage schedules which have been shown to alter the incidence of respiratory distress syndrome. Although glucocorticoids affect renal ammoniagenesis in adults, the antenatal betamethasone trial did not augment ammonia excretion measured during the first day of postnatal life. We speculate that precocious maturation of renal ammoniagenesis cannot be triggered by glucocorticoids during the gestational period studied.