RESUMO
Disturbance of consciousness in patients with multiple myeloma is usually related with uremia, hypercalcemia or hyperviscosity syndrome. Currently, hyperammonemic encephalopathy which accompanies characteristic change of amino acid levels in pheripheral blood has been reported as a rare cause of mental change in multiple myeloma. We experienced a case of hyperammonemic encephalopathy in a 60-year-old man with multiple myeloma who had shown transient response to the combination chemotherapy with melphalan and prednisolone. Measurement of amino acid concentrations in peripheral blood revealed high glycine/tyrosine ratio and low Fisher ratio. In spite of conventional treatment on hyperammonemic encephalopathy, he died of disease progression without improvement of consciousness level.