SHM Converge Scientific Abstract ePoster Gallery-Valproate Related Hyperammonemic Encephalopathy : Diagnostic Dilemma

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This case report describes a 46-year-old woman with polysubstance use, seizures, HIV, and mood disorder treated with valproic acid and quetiapine who was admitted for one week of drowsiness, confusion, and agitation. She also had painful erythema and swelling of the right wrist/hand, and had recently used heroin. Initial evaluation showed no major lab abnormalities except mild hypokalemia; urine drug screen was positive for cocaine and marijuana. Toxicology tests were otherwise negative, valproate level was therapeutic, head CT was normal, and HIV remained well controlled.<br /><br />Because of concern for substance-related or psychiatric causes of altered mental status, she was managed with withdrawal protocols and broad-spectrum antibiotics for the hand infection. Neurology evaluation and EEG/EMG suggested diffuse encephalopathy. When her mental status did not improve, ammonia was checked and found to be elevated at 122 µmol/L, leading to the diagnosis of valproate-induced hyperammonemic encephalopathy (VHE). Valproate and quetiapine were held, and L-carnitine was started. Her ammonia level normalized within five days, and her somnolence improved. Valproate was later restarted at a lower dose with continued L-carnitine.<br /><br />The report emphasizes that VHE can occur even with normal valproate levels and without liver dysfunction, and may be missed when other causes of encephalopathy—such as infection, substance use, or psychiatric illness—are present. The proposed mechanism involves valproate’s interference with the urea cycle and carnitine depletion. The authors stress the importance of maintaining a high index of suspicion for hyperammonemia in patients on valproate who develop unexplained altered mental status, and note that L-carnitine is a reasonable treatment in severe cases.

Asset Subtitle

Khushboo Singh

Meta Tag

Author List Aleesha Kainat, Anjana Chandrasekhara Pillai, Khushboo Singh, Tissa Bijoy George

Category Clinical Vignettes

Concept Valproate-Induced Hyperammonemic Encephalopathy

Concept Altered Mental Status

Concept Hyperammonemia

Concept Valproate Discontinuation

Concept Valproic acid

Distinguished Non-Finalist

Presenter Organization Upmc

Presenting Author Khushboo Singh

Track Adult

Keywords

valproate-induced hyperammonemic encephalopathy

valproic acid

hyperammonemia

altered mental status

encephalopathy

L-carnitine

seizures

HIV

polysubstance use

quetiapine

Valproate-Induced Hyperammonemic Encephalopathy

Altered Mental Status

Hyperammonemia

Valproate Discontinuation

Valproic acid