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Internal Medicine

Training Level

Resident PGY 1


Henry Ford Hospital


Introduction: We describe a rare case of Multiple Myeloma presenting with hyperammonemic encephalopathy.Case: A 76 year-old Caucasian lady was admitted with sudden onset altered mental status. Initial work up included normal Computed Tomography of the head and diffuse background slowing on EEG consistent with metabolic etiology. Her CSF analysis was normal. Ammonia level was elevated at 180 mcg/dL despite the lack of underlying liver disease as evidenced by normal liver enzymes and imaging. She had normocytic anemia with hemoglobin level of 9 g/dL and thrombocytopenia at 90 K/mcL. Kidney function and calcium levels were normal. Further work up for normocytic anemia revealed a large IgG lambda monoclonal protein at 1.8 g/dL. She had normal iron studies, vitamin B12, folate, and no hemolysis or bleeding. Due to suspicion for Multiple Myeloma, patient was started on pulse steroids. Bone marrow biopsy confirmed Multiple Myeloma with 61% plasma cells. There was a modest improvement in her Ammonia level to 90 mcg/dL with Lactulose, however there was no significant change in her mental status. Patient’s clinical situation continued to deteriorate, and she had cardiopulmonary arrest, resulting in anoxic brain injury. Eventually, she passed away before initiating treatment for Multiple Myeloma. Discussion: In very few occasions, hyperammonemic encephalopathy can be the presenting symptom of Multiple Myeloma. The pathophysiology of its occurrence is poorly understood. In the right setting, Multiple Myeloma should be considered in the differential diagnosis for patients presenting with hyperammonemia without underlying liver disease.

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Hyperammonemic Encephalopathy: A Tale of an Innocent Liver