SHM Converge Scientific Abstract ePoster Gallery-Hyperammonemia in Multiple Myeloma

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This case report describes a 73-year-old man with high-risk IgG lambda multiple myeloma (MM) who was admitted for altered mental status (AMS) and weakness. Although AMS in MM is often attributed to causes such as hypercalcemia, hyperviscosity syndrome, or uremia, this case emphasizes hyperammonemia as an important but uncommon alternative diagnosis.<br /><br />The patient had a progressive and treatment-refractory course of MM. He previously received four cycles of bortezomib/lenalidomide/dexamethasone, then daratumumab-dexamethasone in preparation for stem cell transplant, and later required fourth-line treatment with teclistamab due to continued disease progression.<br /><br />During hospitalization, he was initially treated for possible grade 2 ICANS with dexamethasone and tocilizumab, with minimal improvement. Laboratory studies showed rising IgG and free lambda light chain levels, raising concern for hyperviscosity syndrome, so plasmapheresis was started; however, his mental status did not improve. Additional testing revealed markedly elevated ammonia levels, while liver ultrasound showed no hepatocellular disease. He was then treated with lactulose enemas and dialysis, but neither therapy significantly lowered ammonia or improved his AMS.<br /><br />The discussion highlights hyperammonemic metabolic encephalopathy (HME) as a rare paraneoplastic complication of MM. Only a small number of cases have been reported, and the condition is associated with poor prognosis. The mechanism is not fully understood, but ammonia production by myeloma cell lines has been proposed. Treatment options are limited; some reports suggest that antineoplastic therapy such as cyclophosphamide may transiently reduce ammonia levels, implying that controlling the underlying myeloma may be the best approach.<br /><br />Overall, the case underscores the need to consider hyperammonemia in MM patients with unexplained AMS, especially when standard treatments fail.

Asset Subtitle

Devesh Amin, DO

Meta Tag

Author List Ardit Feinaj, Devesh Amin, DO, Geetika Bhatt, MD, Henry Ash, Shreya Patel, DO, Vasu Malhotra, DO

Category Clinical Vignettes

Concept Ammonia

Concept Altered Mental Status

Concept Multiple Myeloma

Concept Hyperammonemic Encephalopathy

Distinguished Non-Finalist

Presenter Organization Lakeland Regional Health Medical Center

Presenting Author Devesh Amin, DO

Track Adult

Keywords

multiple myeloma

hyperammonemia

altered mental status

hyperammonemic encephalopathy

IgG lambda

hyperviscosity syndrome

teclistamab

plasmapheresis

lactulose

paraneoplastic complication

Ammonia

Altered Mental Status

Multiple Myeloma

Hyperammonemic Encephalopathy