Atrial natriuretic factor and postnatal diuresis in respiratory distress syndrome.

To find out if atrial natriuretic factor plays a part in the control of urine output during the initiation alone or throughout postnatal diuresis in neonates with respiratory distress syndrome, atrial natriuretic factor concentrations and clinical and renal variables were measured prospectively three times during the first three days of life in 13 premature infants. Atrial natriuretic factor concentrations rose significantly between the first and second sample times as did the urine output and output:input ratio. By the time that the third sample was taken, atrial natriuretic factor concentration had decreased significantly since the second sample had been taken, while urine flow was maintained. All subjects initiated a spontaneous diuresis that was related to the second concentration of atrial natriuretic factor. With partial correlation analysis a significant relationship was shown between the concentration of atrial natriuretic factor and the maintenance of urine output throughout the study period. Individual hormone concentrations did not, however, correlate with simultaneous renal variables. Changes in the concentrations of atrial natriuretic factor coincided with initiation of spontaneous diuresis in babies with respiratory distress syndrome, and may have a role in the complex mechanisms that maintain this diuresis.