Dr. Writer is a Staff Inpatient Psychiatrist, Audie L. Murphy VA Medical Center, Department of Psychiatry, and Adjunct Assistant Professor, University of Texas Health Science Center, San Antonio, San Antonio, Texas. Dr. Meyer is an Assistant Professor, Department of Psychiatry, Uniformed Services University of the Health Sciences, Bethesda, Maryland. Dr. DeLange is a PGY-4 Resident, University of Texas Health Science Center, San Antonio, San Antonio, Texas.
Disclosures
The authors report no financial relationship with any company whose products are mentioned in this article or with manufacturers of competing products.
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.
