Cases That Test Your Skills

Stabilized schizoaffective disorder; later confusion and depression appears

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References

This last point is critical because it can delay VHE identification and treatment or worse, result in misdiagnosis with accompanying continuation or escalation of VPA dosing as has initially occurred in Mr. D’s case. Similar concerns have been raised2,5 and occurred,5,19 which is not surprising given the frequency of VPA use for psychiatric conditions and symptoms.

Providers should have a low threshold for checking an ammonia level in clinical scenarios that involve any alteration in mental status that may resemble delirium in psychiatric patients treated with valproate. From a preventative perspective, it may be prudent to avoid valproate in psychiatric patients with known VHE risk factors. Either way, promotion of VHE awareness and detection across medical disciplines is paramount.

Bottom Line

Although emergent valproate-related hyperammonemic encephalopathy (VHE) is rare, it represents a potential missed opportunity to detect and correct a reversible delirious process. It is challenging to distinguish VHE from the psychiatric illness that valproate is used to treat. Providers should have a low threshold for checking an ammonia level in clinical scenarios that involve any alteration in mental status that may resemble delirium in psychiatric patients treated with valproate.

Related Resources

  • Thomas KL, La AQ, Punia S, et al. Valproic acid-induced hyperammonemia and minimal hepatic encephalopathy prevalence among psychiatric inpatients. Ann Clin Psychiatry. 2016;28(1):37-42.
  • Holroyd S, Overdyke JT. Hyperammonemia associated with valproic acid use in elderly psychiatric patients. J Neuropsychiatry Clin Neurosci. 2012;24(3):372-374.

Drug Brand Names

Aripiprazole Abilify

Divalproex extended-release Depakote ER
Lisinopril Zestril
Lorazepam Ativan
Metformin Glucophage

Mirtazapine Remeron
Neomycin Neo-Fradin
Simvastatin Zocor

Topiramate Topamax

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