γ-Glutamylornithine excretion in patients with hyperornithinemia

Abstract γ-Glutamylornithine has been identified in urine from patients with the HHH syndrome (hyperornithinemia, hyperammonemia and homocitrullinuria) and with gyrate atrophy associated with hyperornithinemia. The amount of γ-glutamyl-ornithine excreted was 10–15 times higher than that excreted in normal subjects. The level of excretion was comparable in the HHH syndrome subjects and the gyrate atrophy subjects despite the fact that the gyrate atrophy subjects excreted more ornithine. A 100 mg/kg oral challenge of ornithine increased the excretion of γ-glutamylornithine by a factor of three. This increased excretion of γ-glutamylor-nithine was observed in hyperornithinemia patients with different etiologies and is therefore presumably due to the hyperornithinemic state, per se, independent of the underlying defect.