URINARY-EXCRETION OF ALDOSTERONE, ARGININE-VASOPRESSIN AND CORTISOL IN PREMATURE-INFANTS WITH MAXIMUM RENAL ACID STIMULATION

Of 452 low-birth-weight infants who were routinely screened for maximu m renal acid stimulation (MRAS) (urine pH < 5.4), 149 episodes of inci pient late metabolic acidosis (urine pH < 5.4 on 2 consecutive days) w ere randomly allocated to either a control group or treatment with NaH CO3 or NaCl (2 mmol/kg/day each) for 7 days. Urinary excretion of aldo sterone-18-glucuronide (Aldo), arginine vasopressin (AVP) and cortisol was determined in timed urine samples. On day 1, patients with MRAS s howed a tendency towards increased urinary excretion of Aldo compared with infants without MRAS. In patients who received alkali therapy, ur inary excretion of Aldo, AVP and cortisol decreased or showed a trend to lower values from day 1 to day 7, whereas in patients with MRAS but no specific therapy, Aldo and AVP showed a tendency to increase. We c oncluded that persistent MRAS is not only characterized by a reduced r ate of weight gain and a tendency to decreased nitrogen assimilation, but also increased secretion of Aldo and AVP.