EFFECT OF DEXAMETHASONE ON PROTEIN-METABOLISM IN INFANTS WITH BRONCHOPULMONARY DYSPLASIA

Corticosteroids result in protein wasting in human adults and rats. To determine to what extent this therapy affects protein metabolism in p reterm infants, we studied 10 very low birth weight infants before a g radually tapered dexamethasone regimen was started and at day 4 of tre atment (dexamethasone dosage 0.35 +/- 0.09 mg kg(-1) day(-1)), and sev en infants at day 19 of treatment (dexamethasone dosage, 0.10 +/- 0.01 mg kg(-1) day(-1)). Protein breakdown and turnover rates were increas ed at day 4 of treatment but not any more at day 19 of treatment. Prot ein synthesis rate was not significantly affected during dexamethasone therapy. Weight gain was severely diminished during the first week of treatment but not during the next 2 weeks. We conclude that nitrogen balance during high dosages of dexamethasone is significantly lower be cause of an increase in proteolysis and not because of a suppression o f synthesis.