1290 TRANSIENT HYPERAMMONEMIA OF PREMATURITY (THP): RESPONSE TO HEMODIALYSIS (HD)

Abstract

A 2.5 kg male infant delivered at 35 weeks gestation developed generalized seizure activity, then coma at 24 hours of age. Plasma ammonia at 36 hours of age was 2575 μg/dl. The concentration of citrulline in the blood was 109 μM, that of arginine was 145 μM; argininosuccinate was absent, and urinary orotic acid excretion was 46 μg/mg creatinine. Volatile fatty acids in plasma were normal as was the plasma glycine concentration (530 μM). A diagnosis of transient hyperammonemia of prematurity was made and therapy begun. Despite four three-volume exchange transfusions and a constant arginine infusion of 4 mM/kg/day in a single 24 hour period, which increased the plasma arginine and ornithine to greater than 2000 μM, the plasma ammonia concentration remained greater than 1000 μg/dl. The infant underwent three hours of hemodialysis performed via an “umbilical shunt” at 62 hours of age. This lowered ammonia from 2184 to 275 μg/dl and was associated with complete reversal of neurological depression. Ammonia clearance by HD was calculated to be 40 ml/min at a blood flow of 60 ml/min. Ammonia levels continued to fall without further therapy and remained within the normal range (<100 μg/dl) for the duration of hospitalization even after commencement of formula feedings. We conclude that HD is an effective therapy for THP and should be considered in centers equipped for this procedure.