[Thiopurine-induced hyperammonaemic encephalopathy in a patient with Crohn's disease]

Thiopurine drugs, azathioprine (Imuran) and 6-mercaptopurine (6-MP), are immunomodulators that have been shown to be effective at inducing and maintaining remission in inflammatory bowel disease. Although usually well-tolerated, the occurrence of side effects, typically myelotoxicity and hepatotoxicity, is a major drawback. The side effects can be classified as dose-dependent and independent. Both cholestatic hepatitis and endothelial injury, leading to vascular congestion and nodular regenerative hyperplasia, have been described during therapy with thiopurines, which can end up with portal hypertension. These injuries are potentially mediated by different metabolites. In this article we present a case of hyperammonaemic encephalopathy during therapy with 6-MP, possibly the first recorded in the literature, which probably resulted from the combination of thiopurine-induced liver injury with portal hypertension and the presence of spontaneous portosystemic venous shunts.

Valproate-induced hyperammonemic encephalopathy: a brief review

BACKGROUND

This brief review presents a comprehensive evaluation of valproate-induced encephalopathy (VHE) and also discusses potential mechanisms of the condition.

SCOPE

Sodium valproate (VPA) is an effective antiepileptic drug used in neurology as well as in psychiatry, in adults and children. VHE requires early diagnosis and management. Focused research efforts in understanding the condition will help decrease its incidence. Delay in recognition of VHE can result in the development of potentially life-threatening complications.

FINDINGS

Management options are described. Since VPA frequently causes a modest rise in plasma ammonia levels which is asymptomatic, it is important to recognize the symptoms of VHE promptly and to correlate them with the plasma ammonia levels.

CONCLUSIONS

Although there are several case reports on VHE, this review is a comprehensive evaluation of its causes and potential mechanisms. Rapid diagnosis and management will help in reducing VHE-related morbidity.

[Two cases of hyperammonemic patients treated by chemotherapy for colorectal cancer]

We report two patients having hyperammonemic encephalopathy while being treated with chemotherapy for colorectal cancer. The first patient was a 69-year-old man with sigmoid colon cancer, having a massive invasion to the urinary bladder. He received SOX therapy following a pelvic exenteration operation. After the third course of SOX therapy, he presented with general fatigue and repeated seizures, and blood examination showed a high level of serum ammonium. He was diagnosed as hyperammonemic encephalopathy. The second patients was a 60-year-old woman with ascending colon cancer and liver metastasis having portal vein tumor thrombosis, who was given a palliative resection of ascending colon, and then underwent modified FOLFOX6 therapy. At the second course, she fell into a deep coma, and blood examination revealed a high level of serum ammonium. In both patients, treatment with infusion of branched-chain amino acid solutions resolved the symptoms of encephalopathy. Acute neurotoxicity caused by hyperammonemic encephalopathy during chemotherapy for colorectal cancer is rare and not well recognized, but it is a clinically important complication. We should pay more attention to hyperammonemic encephalopathy of patients receiving chemotherapy for colorectal cancer.

Risk factors for hyperammonemia associated with valproic acid therapy in adult epilepsy patients

Hyperammonemia is one of the side effects of treatment with valproic acid (VPA), but the risk factors and mechanisms involved remain obscure. This study analyzed the risk factors for hyperammonemia associated with VPA therapy in adult epilepsy patients. A retrospective analysis of 2724 Japanese patients (1217 males and 1507 females aged from 16 to 76years) treated with VPA between January 2006 and December 2010 were analyzed. The ammonia level increased markedly in a VPA dose-dependent manner, and was significantly elevated in patients who also used hepatic enzyme inducers such as phenytoin (PHT), phenobarbital (PB), carbamazepine (CBZ), and combinations of these drugs. When a blood ammonia level exceeding 200μg/dl was defined as hyperammonemia, the risk factors for hyperammonemia according to multiple regression analysis were a VPA dose >20mg/kg/day (odds ratio (OR): 4.1; 95% confidence interval (CI): 1.6-10.8) and concomitant use of PHT (OR: 11.0; 95% CI: 3.1-38.7), concomitant PB (OR: 4.3; 95% CI: 1.0-17.9), concomitant CBZ (OR: 2.8; 95% CI: 0.6-11.9), and concomitant topiramate (OR: 2.8; 95% CI: 1.2-6.5). Regimens containing multiple inducers were associated with an increased risk of hyperammonemia. Identification of risk factors for hyperammonemia associated with VPA therapy can help to minimize side effects during its clinical use.

Absence of neuropsychological impairment in hyperammonaemia in healthy young adults; possible synergism in development of hepatic encephalopathy (HE) symptoms?

The aetiology of minimal hepatic encephalopathy (mHE) remains unclear. It is generally accepted that hyperammonaemia plays a major role, however there are a multitude of metabolic perturbations present. To determine the contribution of hyperammonaemia to mHE symptom development, ten healthy males (Age:25 ± 5 yrs, BM:76.3 ± 7.1 kg, Height:178.6 ± 4.5 cm, mean ± SD) received two 4 h intravenous infusions of either a 2% ammonium chloride solution (AMM) or a placebo (PLA;0.9% sodium chloride) using a double blind cross-over design. Sensations of fatigue were measured at baseline, 2 and 4 h using the Multidimensional Fatigue Symptom Inventory-Short Form (MFSI-SF) questionnaire. Learning & memory, motor control and cognition were assessed using Rey's Auditory Verbal Learning Test (AVL), Continuous Compensatory Tracking (COMPTRACK) Task and Inhibitory Control Test (ICT) respectively. Arterialised venous blood samples were collected every hour, and analysed for ammonia concentration. There was a significantly higher plasma ammonia concentration in the AMM trial than the PLA trial at every time point during the infusion, peaking at 2 h (57 ± 4 μmol/L PLA, 225 ± 14 μmol/L AMM; p < 0.05). At 2 h there were significantly higher sensations of general fatigue (Z = -2.527, p = 0.008, 2 tailed) and physical fatigue (Z = -2.156, p = 0.027, 2 tailed), and lower sensations of vigour (Z = -2.456, p = 0.012, 2 tailed) for the AMM trial. There were no significant effects on the performance of the psychological tasks. These results demonstrate that hyperammonaemia in the absence of other complications induces significant sensations of fatigue but does not cause the typically observed performance impairment in individuals with mHE. Supporting the hypothesis for synergism between ammonia and other co-factors in mHE.

A case of hyperammonaemic encephalopathy due to valproic acid

A patient with valproic acid induced hyperammonaemic encephalopathy is presented. During chronic treatment with valproic acid this patient developed a potentially life-threatening encephalopathy without signs of liver failure. After discontinuing the valproic acid the patient recovered completely. In the case of a patient presenting with hyperammonaemic encephalopathy, the possibility of the use of valproic acid should not be overlooked.

[Pharmacogenetics focused on special phenotypes]

It is well-known that the patients with autosomal recessive juvenile Parkinsonism (ARJP), which is caused by the loss of function mutation in the Parkin gene, often show psychiatric symptoms such as depression, paranoia, psychosis, panic attacks, anorexia nervosa or suicide attempts. The recently established syndrome, dopamine dysregulation syndrome (DDS), is also frequently observed in the patients with ARJP. These facts might indicate that immature personality, which leads to reactive depression, anxiety, or suicide attempt, and vulnerability of reward system in ARJP, which leads to DDS, are due to loss of function of the Parkin gene product. The present status of molecular genetic studies on other special adverse effects of psychotropic medicines such as hyperammonemia due to valproate and malignant syndrome by antipsychotics was additionally reported.

Vaccines are not associated with metabolic events in children with urea cycle disorders

BACKGROUND

Despite the success of childhood immunizations in prevention of infectious diseases, questions remain about the safety of vaccines in medically fragile children with inborn errors of metabolism such as urea cycle disorders (UCDs). Patients with UCDs are subject to hyperammonemic episodes (HAEs) after infection, fever, or other stressors.

OBJECTIVE

We sought to assess the risk of HAEs that required urgent care or hospitalization after routine vaccinations in pediatric patients with underlying UCDs.

METHODS

This was a retrospective investigation of vaccine safety in children with UCDs within the longitudinal Rare Diseases Clinical Research Consortium for UCD. Postvaccination exposure periods were defined as 7 or 21 days after any immunization. The association of vaccines and HAEs was modeled by using conditional Poisson regression, adjusting for age, and using a self-controlled case series method including all patients with ≥1 HAE and with any vaccine exposure.

RESULTS

The study enrolled 169 children younger than 18 years. Of these children, 74 had records of at least 1 HAE and at least 1 vaccination. With adjustment for age, there was no increase in relative incidence of HAEs in either the 7-day (1.31 [95% confidence interval (CI): 0.80-2.13]) or 21-day (1.05 [95% CI: 0.74-1.47]) exposure period after vaccination compared with HAEs outside of the vaccination periods. No vaccine type was associated with significantly more HAEs.

CONCLUSIONS

We found no statistically significant association between childhood immunizations and HAEs in children with UCDs. The results support the safety of immunization in this medically vulnerable population.

5-FU-induced hyperammonemic encephalopathy in a case of metastatic rectal adenocarcinoid successfully rechallenged with the fluoropyrimidine analog, capecitabine

Neurological complications of both fluorouracil (5-FU) and its oral prodrug, capecitabine, have been described in the literature. This study reported the case of a 70-year-old female with metastatic adenocarcinoid of the rectum who developed hyperammonemic encephalopathy, following infusional 5-FU therapy, manifesting itself as intractable nausea, vomiting, confusion and disorientation. Interestingly, when the patient was rechallenged with the fluoropyrimidine analog, capecitabine, neither hyperammonemia nor symptom recurrence was observed. 5-FU is an integral component of effective anti-neoplastic treatment for metastatic colorectal cancer, but is often discontinued when neurotoxicity develops. This case highlighted the use of capecitabine as an alternative for patients who have demonstrated evidence of 5-FU-induced hyperammonemic encephalopathy. Re-challenging the patient with capecitabine, at a low daily dose intensity, accounted for the overall tolerability of the treatment, as demonstrated by normal ammonia levels and the lack of neurological symptoms.

[Valproate-induced hyperammononemic encefalopathy]

The authors report a case of valproate-induced hyperammononemic encefalopathy whose initial clinical features were represented by increase of pre-existing disturbed-aggressive behaviour.

Adult nonhepatic hyperammonemia: a case report and differential diagnosis

This article presents a case report of nonhepatic hyperammonemia, i.e., elevated serum ammonia secondary to a nonhepatic etiology. It then discusses the importance of broadening one's differential diagnosis to include such nonhepatic causes of elevated ammonia levels, and provides a short review of rarer causes of hyperammonemia in the adult population. Treating the underlying condition is the best way to prevent recurrence of hyperammonemia. However, symptomatic treatment should not be delayed while investigating the underlying source.

[A case of metastatic colorectal cancer suffering from hyperammonemic encephalopathy induced by 5-FU, continuously treated with FOLFOX therapy]

We report a rare case of metastatic colorectal cancer who suffered from hyperammonemic encephalopathy induced by 5- FU and was continuously treated with FOLFOX therapy. A 50-year-old man with ileus was diagnosed with ascending colon cancer Stage IV, and a right hemicolectomy was performed. Postoperative chemotherapy with modified FOLFOX6 was performed. Complications of nausea and vomiting were seen on day 2 , with confusion and cognitive disturbances on day 3 . None of the other radiographic examinations provided an explanation for his symptoms. Laboratory examination revealed hyperammonemia, so branched-chain amino acid solutions and high-volume drip infusion were started for its treatment. His symptoms entirely disappeared on day 4. We changed to chemotherapy for FOLFOX4 using branched-chain amino acid solutions and drip infusion. The tumor marker level normalized following two courses, and CT following ten courses showed that the size of the lung metastasis and abdominal lymph node had reduced significantly. The patient is currently receiving FOLFOX4.

[Redistribution of gastrointestinal ammonia into blood in alcohol coma rat: the role in lethal outcome]

At 3 h after the intragastral administration of ethanol (446 mmol/kg) the blood ammonia concentration in v. portae increased 1.4 times, in v. cava inf. caudally of vv. renales inflow - 2.2 times, cranially of vv. hepaticae - 2.5 times, and in blood obtained by decapitation - by 65%7. The rate of ammonia accumulation in 'avage medium injected intraperitoneally was triple as that in intact rats. The exposure to atmospheric ammoniac (0.84-1.07 mg/l) for 3 h resuited in increasing blood ammonia concentration 2.4 times compared with the isolated ethanol action. The ammonia inhalation promoted the lethal action of ethanol with a dose alteration factor of 0.81 and suppressed gas-exchange. The promotion of the ethanol lethal action by the non-lethal ammonium acetate dosage has been observed. These data suggest that in rat, the coma-inducing ethanol ingestion promotes the translocation of intestinal ammonia into the common bloodstream, which has a detrimental effect on the outcome of alcohol coma.

[A case of 5-fluorouracil-induced hyperammmonia after chemotherapy for metastatic colon cancer]

A 79-year-old woman with colon cancer and multiple liver metastases was admitted to our hospital for systemic chemotherapy. She underwent first cycle of modified FOLFOX6 chemotherapy. She was confused on treatment day 5. Blood test revealed her serum ammonia level to be 121 microg/dl. We diagnosed 5-fluorouracil (5FU)-induced hyperammonemia. Conservative treatment resulted in improvement of metal status. The reason for hyperammonemia after administration of 5FU was the excess production of ammonium from metabolites of 5FU.

[A case of hyperammonemia with encephalopathy related to FOLFIRI chemotherapy for advanced colon cancer]

A 50-year-old man undergoing operations for sigmoid colon cancer, small intestine invasion, and liver metastasis was given adjuvant chemotherapy postoperatively. During the course, lung, brain and bone metastasis were found, FOLFIRI therapy was started. Fifth FOLFIRI therapy was performed, but on the night of the next day, he was transported on an emergency basis to our hospital because of a coma. Laboratory examination revealed hyperammonemia, so aminoleban was started for its treatment. After 3 days in the hospital, consciousness and serum ammonia were improved. Cases of hyperammonemia caused by 5-FU have been reported in the literature, and this case was diagnosed with the same. Hyperammonemia should be taken into account as a differential diagnosis in the disturbance of consciousness in chemotherapy.

[A case of hyperammonemic encephalopathy in a patient with recurrent colon cancer treated with modified FOLFOX6]

FOLFOX therapy is a commonly used chemotherapeutic regimen against recurrent and unresectable colon cancer. However, its acute neurotoxicity is rare and not well recognized. We herein report a case of mFOLFOX6-induced hyperammonemic encephalopathy in a patient having recurrent colon cancer. A 74-year-old female with a history of sigmoid colon cancer was diagnosed as liver, lung, and peritoneal recurrences by surveillance CT and PET/CT. She was initially treated with modified FOLFOX6 therapy. After completing treatment, she presented with sudden onset of confusion, cognitive disturbances, and repeated seizures. None of the other radiographic examinations and laboratory tests provided an explanation for her symptoms except hyperammonemia. She was treated with branched-chain amino acid solutions and high-volume drip infusion, 6 hours after which the encephalopathy resolved. Clinicians should be aware of the adverse hyperammonemia induced by mFOLFOX6 when patients treated with mFOLFOX6 present with neurological disorders.

Valproate induced non hepatic hyperammonaemic encephalopathy (VNHE)--a study from tertiary care referral university hospital, north India

OBJECTIVE

To report and discuss twelve cases of Valproate (VPA) induced hyperammonaemic encephalopathy without liver failure in subjects receiving VPA therapy.

METHODS

This study was conducted in the department of Neurology, G.B. Pant Hospital, New Delhi from January 2000 to December 2006. The subjects were on treatment with VPA alone or in combination with other anti epileptic drugs and developed symptoms of encephalopathy. The data collected included the type of epilepsy, the dose of VPA and other co-administered anti epileptic drugs (AED), their serum levels, clinical presentation, relevant radiological and laboratory investigations, serum ammonia levels, the measures taken to treat the patient and their outcome.

RESULTS

A total of twelve cases of VPA induced Non hepatic hyperammonemic encephalopathy (VNHE) were studied, out of which six were males and six females. The age ranged from 2-75 years with mean age of 21.33 +/- 20.84 years. Four subjects were on VPA alone and the others were also on concomitant AEDs. All the above subjects presented with either confusion or altered sensorium (100%). None of the subjects had any other demonstrable cause of encephalopathy. The serum ammonia level in these subjects ranged from 77.3-345 micromol/L with mean of 163.98 micromol/L +/- 48.67 (normal range 10-47 micromol/L). The serum VPA level in this study group ranged from 63-132.6 microg/ml with mean of 93.44 microg/ml +/- 31.77 (normal range 50-100 microg/ml).

CONCLUSIONS

In any patient on VPA therapy, who develops signs and symptoms suggestive of encephalopathy, even in the presence of normal liver function, VNHE should be suspected. Fortunately, it has a good prognosis and the early withdrawl of VPA leads to improvement in almost all cases.

[Valproate-induced hyperammonemic encephalopathy. Review of cases in the psychiatric setting]

Valproate-induced hyperammonemic encephalopathy is a rare but severe and potentially fatal adverse event. Frequently, the use of valproic acid produces an elevation of ammonia levels. In some people, this is associated with the development of encephalopathy without evidence of liver failure, usually reversible with discontinuation or dose reduction. Although there is important evidence about this adverse event in patients with neurologic disorders, the data in the psychiatric setting is scarce. We review the available studies and case reports about valproate-induced hyperammonemic encephalopathy in people treated with valproic acid for psychiatric disorders. We describe the clinical and therapeutic characteristics, and the physiology of this adverse event.