EFFECTS OF EARLY POSTNATAL DEXAMETHASONE THERAPY ON CALCIUM HOMEOSTASIS AND BONE-GROWTH IN PRETERM INFANTS WITH RESPIRATORY-DISTRESS SYNDROME

The effects of dexamethasone therapy on calcium homeostasis and bone g rowth were evaluated in 49 infants (24 placebo and 25 dexamethasone) w ho participated in a double-blind trial of early dexamethasone therapy for the prevention of chronic lung disease. Dexamethasone (0.25 mg kg (-1) b.i.d. on d 1-7; 0.12 mg kg(-1) b,i,d. on d 8-14; 0.05 mg kg(-1) b.i.d. on d 15-21; 0.02 mg kg(-1) b.i.d. on d 22-28) or saline placebo was given i.v. Serum calcium (Ca), phosphorus (P) and parathyroid hor mone (PTH), and the corresponding urinary excretion of calcium (FECa) and phosphorus (FEp) were measured on d 2, 3, 7, 10, 14, 21 and 28 aft er starting the study. Radiographic evaluations of bone growth were al so evaluated. Infants in the dexamethasone group had significantly hig her PTH on d 2 (p < 0.01), 7 and 14 (p < 0.05) than infants in the pla cebo group. The dexamethasone-treated infants also had significantly h igher FEp on d 2, 7 and 14 (p < 0.05) and lower FECa on d 7 and 14 (p < 0.05) than control infants. There was no significant difference betw een the groups in bone growth during the study. It was concluded that early dexamethasone therapy causes a transient elevation in PTH withou t apparent change in bone growth. The long-term effect remains to be e valuated further.