LAUSR

I read with interest the recent case report on kernicterus in a male neonate with ornithine transcarbamylase deficiency (OTC). This novel finding was also notable in that it occurred at a low serum unconjugated bilirubin level (11.55 mg/100 mL). The authors speculate that hyperammonemia may be a risk factor for bilirubin neurotoxicity perhaps via impairment of the blood–brain barrier and enhanced cerebral bilirubin diffusion. However, an alternative explanation should be considered, namely the sodium benzoate treatment the infant received as part of the management of OTC and hyperammonemia. Sodium benzoate is a known potent displacer of bilirubin from albumin and there appears to be a considerable interpatient variability in benzoate metabolism. What dosage of sodium benzoate was used in this patient and/or were serum benzoate concentrations measured? The possibility that benzoate levels were elevated and competed with bilirubin for albumin binding leading to the occurrence of kernicterus at low serum bilirubin levels should be considered in this case.