Transient hyperammonaemia in a patient with confusion: challenges with the differential diagnosis

Labib, Peter; Wing, Stevan C; Bhowmik, Angshu

doi:10.1136/bcr.03.2011.3961

Cited by 8 publications

(7 citation statements)

References 6 publications

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“…In our patient, the elevated blood ammonia level and the rapid resolution of symptoms coupled with the reduction of his blood ammonia level led us to suspect that hyperammonemia may have accounted for his presentation. His clinical presentation and subsequent clinical course were similar to those of patients described in prior case reports of noncirrhotic/nonhepatic hyperammonemia (2)(3)(4)(5)(6)(7)(8).…”

Section: Discussionsupporting

confidence: 57%

“…Secondary hyperammonemia occurs commonly in the presence of hepatic disorders leading to portosystemic encephalopathy, but can occur in the absence of hepatic dysfunction in disorders like Reye's syndrome, ureterosigmoidostomy, and infection in a neurogenic bladder. Drug toxicity as a result of disruption of mitochondrial pathways by drugs like cyanide, carbamazepine, valproic acid, iron, and cytotoxics can also cause secondary hyperammonemia, and this is thought to be the main mechanism by which nonhepatic or noncirrhotic hyperammonemia can occur in people exposed to these drugs (2,(4)(5)(6)(7)(8)(9).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Noncirrhotic Hyperammonemia Causing Relapsing Altered Mental Status

Odigwe¹,

Khatiwada²,

Holbrook³

et al. 2015

Baylor University Medical Center Proceedings

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Section: Discussionsupporting

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Noncirrhotic Hyperammonemia Causing Relapsing Altered Mental Status

Odigwe¹,

Khatiwada²,

Holbrook³

et al. 2015

Baylor University Medical Center Proceedings

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“…Although hyperammonemia is generally associated with VPA, monotherapy with phenytoin (PHT), carbamazepine (CBZ), primidone, or acetazolamide can occasionally cause hyperammonemia (Ambrosetto et al., ; Katano et al., ; Kim et al., ; Adams et al., ; Labib et al., ). In addition, ZNS, TPM, acetazolamide, and sulthiame inhibit carbonic anhydrase and block bicarbonate re‐uptake, so drug‐induced metabolic acidosis could lead to an increase of the blood ammonia level in patients taking these AEDs.…”

mentioning

confidence: 99%

Risk factors for hyperammonemia in pediatric patients with epilepsy

et al. 2013

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SUMMARYPurpose: To identify risk factors for hyperammonemia in pediatric patients with epilepsy. Methods: A total of 2,944 pediatric patients (ages 0-15 years) were classified into the following three groups: a group without drug treatment (n = 445, group I), a group receiving antiepileptic drugs other than valproic acid (VPA) (n = 673, group II), and a VPA-treated group (n = 1,826, group III). Hyperammonemia was defined as a plasma ammonia level exceeding 100 lg/dl with reference to the standard range and previous reports. Key Findings: The mean ammonia level of groups I, II, and III was 36.0, 56.0, and 86.8 lg/dl, respectively, and the incidence of hyperammonemia was 1.6%, 7.7%, and 31.7%, respectively. In each group, the mean ammonia level of patients aged 3 years or younger was significantly higher than that of patients aged 4-15 years. In group II, concomitant use of topiramate and zonisamide were risk factors for hyperammonemia (adjusted odds ratio [OR] 3.9, 95% confidence interval [CI] 1.7-9.2, and OR 3.5, 95% CI 1.9-6.5, respectively). In group III, the ammonia level increased in a VPA dose-dependent manner. At a VPA dose of 30 mg/kg, there was 4.3-fold increase in the incidence of hyperammonemia. The other significant risk factors identified were female gender (OR 1.3, 95% CI 1.0-1.6), symptomatic generalized epilepsy (OR 1.4, 95% CI 1.1-1.8), and the concomitant use of phenytoin (OR 4.7, 95% CI 3.3-6.9), phenobarbital (OR 2.2. 95% CI 1.6-3.2), acetazolamide (OR 6.6, 95% CI 2.5-17.2), topiramate, or zonisamide. Significance: A young age and concomitant use of carbonic anhydrase inhibitors are associated with an increased risk of hyperammonemia regardless of whether the patient is taking VPA. In patients receiving VPA, concomitant use of phenytoin and/or phenobarbital enhances the risk of hyperammonemia. An increase in ammonia can be caused by multiple factors. Our results may help clinicians to avoid problems of hyperammonemia. KEY WORDS: Hyperammonemia, Epilepsy, Children, Risk factor, Valproic acid, Phenytoin.Hyperammonemia is a frequent problem associated with antiepileptic drugs (AEDs) that can lead to vomiting, aggression, ataxia, and exacerbation of seizures. Acute hyperammonemia can also cause cerebral edema and severe brain damage (encephalopathy), whereas chronic hyperammonemia due to metabolic disorders is associated with developmental delay and intellectual disability (Cagnon & Braissant, 2007;Lichter-Konecki, 2008). Among the AEDs, valproic acid (VPA) is recommended as a first-line treatment for generalized epilepsy. Although VPA can cause an increase of the blood ammonia level, VPA therapy is rarely associated with hyperammonemic encephalopathy.The exact relationship between symptoms and the ammonia level remains unclear. Murphy and Marquardt (1982) reported that patients with hyperammonemia not exceeding 240 lg/dl were asymptomatic. In contrast, Coulter and Allen (1981) recommended reducing the VPA dose when the ammonia level exceeded 100 lg/dl. Our data (see later) indicate that hyperammo...

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“…It may also happen with normal hepatic function when mitochondrial pathways are interrupted by Reye's syndrome or medications, such as valproic acid, carbamazepine, salicylate, topiramate, or cytotoxic agents . Additionally, renal tubular acidosis, urinary tract dilatation or urinary tract infection, pregnancy, and hypoglycin may contribute to nonhepatic hyperammonemia.…”

Section: Discussionmentioning

confidence: 99%