Postpartum "psychosis" in mild argininosuccinate synthetase deficiency

Urea cycle disorders are relatively rare but well-established causes of postpartum coma and death. Such clinical presentations have been reported previously in ornithine transcarbamylase and carbamyl phosphate synthetase deficiencies.

We describe a woman, without prior symptoms of metabolic disease, who presented with hyperammonemia and psychiatric symptoms in the postpartum period. Initial diagnoses included acute fatty liver of pregnancy and postpartum psychosis. She was later found to have argininosuccinate synthetase deficiency after further metabolic investigations. Rare heterozygous mutations in the argininosuccinate synthetase gene were identified.

Urea cycle disorders may present initially with postpartum psychiatric symptoms and may represent an underrecognized cause of "postpartum psychosis." We recommend obtaining metabolic studies in women with neurologic or severe psychiatric symptoms in the postpartum period.