The effect of dexamethasone on growth, mineral balance and bone mineralisation in preterm infants with chronic lung disease.

UNLABELLED: The aim of this prospective longitudinal study was to observe the effects of treatment with dexamethasone on somatic growth, mineral balance and bone mineralisation in very low birth weight (VLBW) preterm infants with chronic lung disease (CLD). Dexamethasone was started at a dose of 500 microg/kg body weight per day for 3 days followed by gradually decreasing doses for a total period of 3 weeks' treatment if the infant was still mechanically ventilated in the 3rd postnatal week and had signs of CLD on the chest radiograph. Eleven infants with CLD treated with dexamethasone were studied. Administration of dexamethasone treatment was associated with significantly (P < 0.05) lower weight velocity, head circumference velocity, lower leg length (measured by the neonatal knemometer) velocity compared to pre-treatment changes. The start of dexamethasone treatment was also associated with a fall in calcium absorption (61% to 41.7%, P < 0.05) calcium retention (60.8% to 40.6%, P < 0.05) and phosphate retention (65% to 39.6%, P < 0.05); phosphate absorption was not significantly affected (88.8% to 92%, P > 0.05). Somatic growth and mineral balance improved during the immediate post-treatment period. Acute disturbances of bone mineral content (measured by dual energy radiographic densitometry), plasma calcium and phosphate were also seen but not reaching statistical significance at the P < 0.05 level.
CONCLUSION: The start of steroids is associated with a rapid and significant fall in growth velocity, calcium absorption and calcium and phosphate retention in infants with chronic lung disease with recovery occurring after completion of steroid treatment.