Peritoneal Dialysis in Infant Methylmalonic Acidemia: Effective Management Despite Sterile Peritonitis

Methylmalonic acidemia (MMA) is one of the rare inherited metabolic disorders, and the affected patients usually suffer from repeated life-threatening metabolic crises in which hyperammonemia and acidosis are observed. Although continuous venovenous hemodialysis is considered the first choice for extracorporeal detoxification in neonates and infants, the available experience regarding peritoneal dialysis in this group of patients is still limited, and how to optimally manage the complications of dialysis has not been clearly described. We report the case of a three-month-old female infant with isolated MMA who was brought in with vomiting for four days, cough for seven days, and fever for one day. Even after she was started on sodium benzoate, L-carnitine, and sodium bicarbonate, encephalopathy gradually became worse, plasma ammonia level increased from 188 μmol/L to 332 μmol/L, and severe metabolic acidosis was observed (bicarbonate: 9 mEq/L). Peritoneal dialysis was then started, and the metabolic response was found to be excellent: ammonia level came down to 86 μmol/L after eight cycles of dialysis and further to 61 μmol/L on hospital day four. After completion of 17 cycles of dialysis, culture-negative peritonitis was noted in the patient (150 cells/mm³ with 57% neutrophils), and this was managed by escalation of antibiotics together with removal of the catheter. The infant was finally discharged on day 23 in stable condition, with the ammonia level back to normal (49 μmol/L) and the metabolic acidosis showing resolution. From the present case, it can be stated that peritoneal dialysis is effective for the management of severe hyperammonemia in infants suffering from MMA, and rapid correction of the metabolic disturbance was achieved even though the course was complicated by peritonitis. The outcome obtained in our patient supports the expert consensus that, in this age group, peritoneal dialysis can be used as a reasonable alternative to continuous renal replacement therapy, especially at centers where pediatric peritoneal dialysis experience is available.