Pearls & Oy-sters: Chemotherapy-associated hyperammonemic encephalopathy

The Story of Ammonia in Liver Disease: An Unraveling Continuum

Hyperammonemia and liver disease are closely linked. Most of the ammonia in our body is produced by transamination and deamination activities involving amino acid, purine, pyrimidines, and biogenic amines, and from the intestine by bacterial splitting of urea. The only way of excretion from the body is by hepatic conversion of ammonia to urea. Hyperammonemia is associated with widespread toxicities such as cerebral edema, hepatic encephalopathy, immune dysfunction, promoting fibrosis, and carcinogenesis. Over the past two decades, it has been increasingly utilized for prognostication of cirrhosis, acute liver failure as well as acute on chronic liver failure. The laboratory assessment of hyperammonemia has certain limitations, despite which its value in the assessment of various forms of liver disease cannot be negated. It may soon become an important tool to make therapeutic decisions about the use of prophylactic and definitive treatment in various forms of liver disease.

Sunitinib-induced hyperammonemic encephalopathy in metastatic gastrointestinal stromal tumors: A case report

BACKGROUND

Sunitinib, a multi-targeted tyrosine kinase inhibitor (TKI), has been approved for the salvage treatment of gastrointestinal stromal tumors (GIST). Hyperammonemic encephalopathy is a rare but severe complication of sunitinib use. Here, we present the case of a 66-year-old male with metastatic GIST without underlying liver cirrhosis who developed sunitinib-induced hyperammonemic encephalopathy.

CASE SUMMARY

A 66-year-old male with metastatic GIST was admitted because of reduced consciousness. Imatinib was administered as the first-line systemic therapy. He experienced repeated episodes of peritonitis due to tumor perforation, and surgery was performed. Progressive disease was confirmed based on increased liver metastasis, and sunitinib was initiated as a salvage treatment. However, 23 d after the third course of sunitinib, he presented to the emergency room with an episode of altered consciousness and behavioral changes. Based on the patient clinical history and examination findings, sunitinib-induced encephalopathy was suspected. Sunitinib was discontinued, and the patient was treated for hyperammonemia. The patient had a normal level of consciousness four days later, and the serum ammonia level gradually decreased. No further neurological symptoms were reported in subsequent follow-ups.

CONCLUSION

TKI-induced hyperammonemic encephalopathy is potentially life-threatening. Patients receiving TKIs experiencing adverse reactions should undergo systemic evaluation and prompt treatment.