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A3355 - Severe Hyperammonemia Caused by Cryptococcal Meningitis
Author Block: R. Masroujeh, C. V. Teba; Pulmonary and Critical Care, University Hospitals Cleveland Medical Center, Cleveland, OH, United States.
Introduction: Severe hyperammonemia is a life-threatening condition that can cause altered mental status and diffuse cerebral edema. We present an unusual case of severe hyperammonemia secondary to Cryptococcal meningoencephalitis, which has never been previously described.
Case Description: A 59-year-old man known case of biopsy-proven focal segmental glomerulosclerosis (FSGS) on Prednisone and Mycophenolate Mofetil presented with confusion, nausea, vomiting, and weakness. He was found to be in acute kidney injury, initially thought to be secondary to diuretics. Despite holding diuretics and IV hydration, his kidney function and mental status continued to worsen. He was transferred to ICU 4 days after admission, and was intubated for airway protection. Workup at ICU transfer time revealed elevated ammonia level (660 μmol/L). Patient was urgently started on Lactulose, Carnitine, and hemodialysis for his uremia and hyperammonemia. Despite long dialysis sessions, ammonia level remained elevated and he had to be switched to continuous venovenous hemofiltration (CVVH). Three days following ICU transfer, blood cultures grew Cryptococcus neoformans. Lumbar puncture was performed and confirmed Cryptococcal meningitis. The patient was started on liposomal amphotericin, and flucytosine with sterilization of his serial blood and CSF cultures. Metabolic workup for possible urea cycle defects and methylmalonic acidemia revealed no abnormalities. His ammonia level normalized after anti-fungal initiation and the patient started showing signs of slow neurologic improvement. After three weeks in the hospital, the patient was discharged to a long-term care facility on oral fluconazole.
Discussion: Hyperammonemia is a medical and neurosurgical emergency. High blood ammonia concentration may cause permanent neurologic damage secondary to cerebral edema. The most common cause of hyperammonemia in adult is liver disease. Less common causes include urinary tract infection with urease producing organisms, valproic acid overdose, and inborn errors of metabolism. Cryptococcus neoformans is one of the organisms that do produce urease enzyme, which is responsible for the production of ammonia. Our patient had no error in metabolism and his hyperammonemia was driven by the combination of overwhelming Cryptococcal infection combined with kidney dysfunction. This case brings to attention the need to suspect Cryptococcal infection in patients with unexplained hyperammonemia. Equally important is to test for hyperammonemia in patients diagnosed with Cryptococcus to avoid its detrimental effects.