Effect of low-dose dopamine infusion on prolactin and thyrotropin secretion in preterm infants with hyaline membrane disease.

The effect of low-dose (2-4 micrograms/kg/min) and long-term (greater than or equal to 46 h) dopamine infusion on serum prolactin and thyrotropin concentrations was investigated in 8 preterm infants with hyaline membrane disease. Dopamine was administered for systemic hypotension and/or for impending renal failure. Serum prolactin decreased from 1,314.5 +/- 422.7 microU/ml to 489.9 +/- 464.1 microU/ml (p less than 0.005), while serum thyrotropin fell from 3.77 +/- 2.27 microU/ml to 1.01 +/- 0.25 microU/ml (p less than 0.025) during dopamine infusion. Our data indicate that exogenous dopamine exerts an inhibitory effect on the secretion of prolactin and thyrotropin even in the sick preterm neonate. The role of prolactin in fetal lung maturation and in regulation of the neonatal tissue water stores is discussed. The results of the present study are also useful in explaining the renal effects of long-term low-dose dopamine infusion in the sick preterm infant.