Continuous Venovenous Hemodiafilteration for Extremely High Ammonia Levels in Methyl Malonic Acidemia

Excerpt

To the Editor: A 3-d-old baby boy was admitted for poor feeding and lethargy for 1 d. He was 2nd born to parents of second degree consanguineous marriage, delivered at term with birth weight- 2.8 kg and cried at birth. On examination, he weighed 2.5 kg, was encephalopathic and had acidotic breathing. Systemic examination was normal. Investigations revealed normal blood counts, blood glucose- 10 mg/dl, pH- 6.9, serum bicarbonate- 5 mmol/L, plasma ammonia- 1800 μmol/L, lactate- 1.6 mmol/L and 4+ ketonuria. Organic acidemia was considered and the child was kept nil oral and was started on parenteral dextrose, Sodium benzoate (400 mg/kg/d) and Arginine (300 mg/kg/d). Plasma acyl carnitine showed elevated propionyl carnitine 14.5 μmol/L (0.21–3.79). Urine organic acids showed elevated methyl malonic and methyl citric acid (9535 μmol/L and 9986 μmol/L respectively), confirming methyl malonic acidemia (MMA). Peritoneal dialysis (PD) was commenced but in view of persisting encephalopathy, acidosis and rising ammonia (1920 μmol/L), continuous veno venous hemodiafiltration (CVVHDF) was performed using single-lumen catheters and the sites for insertion were the umbilical vein (access limb) and femoral vein (return limb) using PrismaFlex (Baxter) continuous renal replacement therapy (CRRT) system. Extracorporeal circuit was primed using peripheral red blood cells (PRBC). The Prismasol B0 bags (Baxter) were used both for dialysate and replacement fluid solutions. Anticoagulation was achieved using heparin. Within 4 h, ammonia levels dropped from 1920 to 990 μmol/L. However encephalopathy persisted and he succumbed on day 5 of life. Molecular gene testing revealed homozygous mutation in exon 8 of MUT gene (c.1531C > T) confirming MMA and both parents were heterozygous carriers for the same. …