Determine blood ammonia level in adults with unexplained lethargy or coma. Ammonia levels usually are 10-20 times higher than reference range. Blood amino acid changes are not specific to provide a diagnosis but are important in the differentiation of CPS deficiency from other urea cycle disorders. Urine orotic acid will be in reference range. Urine organic acid analysis is important to rule out organic acid disorders.
Definitive testing requires liver biopsy and enzyme analysis.
Molecular genetic diagnosis may be available. Depending upon clinical status and level of blood ammonia, the logical first step is to reduce protein intake and attempt to maintain energy intake. Intravenous sodium benzoate and sodium phenylacetate may helpful. In case of extremely high blood ammonia, rapid treatment by hemodialysis is indicated. Benzoate is transaminated to form hippuric acid, which is rapidly cleared by the kidney.