Hyperammonaemia--an important cause of encephalopathy: three case reports

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

Hyperammonaemia is often seen in the context of decompensated liver disease. It may also be triggered by stressful medical conditions in adults with partial enzyme deficiencies of the urea cycle. Occasionally, non-hepatic causes can result in hyperammonaemia severe enough to cause symptoms. The authors report the case of a 52-year-old Turkish woman who presented with acute-on-chronic confusion, drowsiness and lethargy. Laboratory investigations revealed hyperammonaemia which had an unclear cause. Although first thought to be secondary to a concurrent urinary tract infection, the high serum ammonia was eventually attributed to her carbamazepine. The authors recommend that doctors should include urinary tract infection and iatrogenic causes in their differential diagnosis in patients with hyperammonaemia and neurological symptoms, especially when this may be misleading in the diagnostic process.

Valproic Acid-induced hyperammonemia in the elderly: a review of the literature

Valproic acid and its derivatives are commonly used to treat many psychiatric conditions in the elderly. Hyperammonemia is a less common but important side effect of these drugs. The elderly patient appears highly vulnerable to this side effect of this group of medications. In this paper, we systematically review the published literature for hyperammonemia induced by valproic acid and its derivatives. We describe the three reported cases and review possible treatment strategies for this condition.