Rare Case of Hyperammnia

Introduction: Krebs-Henseleit cycle that is located in hepatic cells is essential to produce urea from ammonia. Hyperammonia occurs due to any defect in one of the six enzymes of this cycle. However, it is less common in mutations of arginase, the last enzyme of the cycle. Arginase deficiency, which is an autosomal recessive metabolic disorder, is the least prevalent between the other causes of urea cycle disorders. It presents with recurrent seizure, spastic diplagia, phsychomotor regression but not hypeammonia most of the time. case of arginase deficiency is described in this article. case presentation 3-month girl was admitted in the pediatric intensive unit because of respiratory distress, Whizzing and partial seizure. at the time of admission her condition was bad. Organomegaly has not been detected through physical examination. Laboratory tests revealed elevated liver transaminases, PT and PTT. Antibiotic therapy was started, but due to recurrent seizure Ammonia level was checked which was 242 µg/dl. Sodium benzoate was administered and specific metabolic work up (acylcarnitine profile and urine organic acid) was requested. Her seizure was controlled and ammonia level decreased to normal range, so sodium benzoate was tapered. Acylcarnitine profile and urine organic acid were normal, but serum amino acid levels (HPLC) showed elevated arginine, which was repeated in reliable laboratory and arginine level was more than times of the normal level. Ammonia level was increased little more than normal level again. Actually, she was diagnosed as arginase deficiency and treated with urea cycle disorder formula and breast milk simultaneously, sodium benzoate and carnitine. She was followed by checking ammonia and serum amino acid levels (HPLC). Arginine level never comes to normal range, but ammonia level was normal by using sodium benzoate. The Seizure that was controlled by phenobarbital has not occurred again and her development was acceptable according to her age.Conclusion: Although the urea cycle disorder is rare disease, in any patient with loss of consciousness or recurrent seizure and elevated ammonia level should be in thought in order to not miss this treatable disease. Moreover arginase deficiency does not present with sever hyperammonia. However, mild elevation of ammonia can be seen in this disorder.

کلیدواژه ها:

Hyperammonia ، Urea cycle disorder ، Arginase deficiency