vitamin-b-12 and Hyperammonemia

Ammonia is a major neurotoxic substance associated with the complex pathogenesis of hepatic encephalopathy. Although several primary and secondary conditions have been reported to cause hyperammonemia, in veterinary medicine this condition is considered primarily associated with hepatic disease or portosystemic shunting. Only a few cases of inherited urea cycle enzyme deficiency and organic acid metabolic disorders have been reported in cats with hyperammonemia. To the best of our knowledge, this is the first report of hyperammonemia in a cat caused by accumulation of methylmalonic acid (MMA) secondary to functional cobalamin deficiency. A 2-year-old spayed female Turkish Angora cat exhibited postprandial depression with a 3-month history of hyperammonemia. Serum protein C and bile acid concentrations were normal. Plasma amino acid analysis revealed a deficiency of urea cycle amino acids. Although the serum cobalamin concentration was markedly high, there was no evidence of inflammatory, hepatic, or renal disease or neoplasia on blood, ultrasonographic, and computed tomographic examination. Gas chromatography-mass spectrometry revealed a high MMA concentration in the urine. Based on the results, functional cobalamin deficiency was diagnosed. Following oral amino acid supplementation and initiation of a low-protein diet, the serum ammonia level returned to normal and the postprandial depression improved. Urea cycle amino acid deficiency secondary to functional cobalamin deficiency presumably caused hyperammonemia due to MMA accumulation in this case.

Topics: Amino Acids; Ammonia; Animals; Cat Diseases; Cats; Female; Hyperammonemia; Methylmalonic Acid; Urea; Vitamin B 12; Vitamin B 12 Deficiency

A 26-year-old man presented at the emergency department with confusion and decreased consciousness after several days of vomiting. In the preceding 6 months, he had used a 2-litre tank of nitrous oxide (N

Topics: Adult; Brain Diseases, Metabolic; Confusion; Consciousness Disorders; Diagnosis, Differential; Gastrointestinal Agents; Humans; Hyperammonemia; Lactulose; Male; Nitrous Oxide; Treatment Outcome; Vitamin B 12; Vitamin B 12 Deficiency; Vitamin B Complex; Vomiting

PRESENTING SIGNS AND INITIAL INVESTIGATIONS: An 8-year-old female spayed British shorthair cat was presented with a history of waxing and waning neurological signs. Neuroanatomical localisation was consistent with a diffuse forebrain disease. Blood ammonia concentration was increased. Abdominal ultrasonography and a bile acid stimulation test were normal. Magnetic resonance imaging (MRI) revealed hyperintense, bilaterally symmetrical, diffuse lesions on T2-weighted sequences, predominantly, but not exclusively, affecting the grey matter. Serum cobalamin (vitamin B12) concentration was low. Hypocobalaminaemia resulting in a urea cycle abnormality was considered a likely cause of the hyperammonaemia.. Daily cobalamin injections resulted in a rapid clinical improvement. Eight weeks into treatment neurological examination was unremarkable and there was complete resolution of the MRI lesions.. This is the first reported case of acquired feline hypocobalaminaemia resulting in an encephalopathy. Additionally, this case is unique in describing reversible brain MRI abnormalities in a cobalamin-deficient companion animal.

Topics: Animals; Brain Diseases, Metabolic; Cat Diseases; Cats; Dietary Supplements; Female; Hyperammonemia; Magnetic Resonance Imaging; Treatment Outcome; Vitamin B 12; Vitamin B 12 Deficiency

A 10-year-old domestic shorthair cat showed anorexia, lethargy and ptyalism with hyperammonaemia. Portosystemic shunts were not identified by computed tomography angiography. Biopsy results revealed mild interstinal nephritis and no lesion in the liver. Analysis of urine revealed the presence of a high methylmalonic acid (MMA) concentration. Serum cobalamin (vitamin B(12)) and serum feline trypsin-like immunoreactivity levels were also markedly low. The cat was diagnosed as having exocrine pancreatic insufficiency (EPI). After 5 weeks of parenteral cobalamin supplementation, serum cobalamin concentration had increased and urinary MMA concentration had decreased. This case suggests that hyperammonaemia may be caused by accumulation of MMA due to cobalamin malabsorption secondary to feline EPI.

Topics: Animals; Cat Diseases; Cats; Exocrine Pancreatic Insufficiency; Hyperammonemia; Malabsorption Syndromes; Methylmalonic Acid; Vitamin B 12; Vitamin B Complex