Abnormal urinary excretion of polyamines in HHH syndrome (hyperornithinemia associated with hyperammonemia and homocitrullinuria).

The HHH syndrome (hyperornithinemia associated with hyperammonemia and homocitrullinuria) is characterized by a very rare genetic defect of ornithine transport in mitochondrial membrane. We first demonstrated that a patient with HHH syndrome excreted about 6 times higher amount of polyamines in urine than the control when supplemented with high protein diets and ornithine loading. Each urinary polyamine fraction measured by HPLC method in HHH syndrome appears to be increased, as compared with those of the control. These data suggest that increased urinary excretion of polyamines in this syndrome is closely related to overflowing of plasma polyamine due to an ornithine transport defect in the mitochondrial membrane.