Hyperammonaemia due to cobalamin malabsorption in a cat with exocrine pancreatic insufficiency

Abstract

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.

Feline Exocrine Pancreatic Insufficiency: A Retrospective Study of 150 Cases

“…Exocrine pancreatic insufficiency (EPI) is characterized by inadequate production of pancreatic enzymes from pancreatic acinar cells and has been previously considered rare in the cat . The related literature consists mainly of case reports of confirmed or suspected EPI cases in cats, with only 10 reports published between 1975 and 2009 . In addition, there have been only 2 small case series of EPI in cats that have been reported in the English peer‐reviewed literature.…”

Effects of 6 Weeks of Parenteral Cobalamin Supplementation on Clinical and Biochemical Variables in Cats with Gastrointestinal Disease

“…[7][8][9] Studies examining biochemical Cbl deficiency in cats have focused on serum MMA concentration, [7][8][9][10][11] and urine MMA concentration has been only sporadically reported. 6,[12][13][14] In humans, a linear relationship exists between serum and urine MMA concentrations. 15 In veterinary medicine, comparisons between serum and urine MMA concentrations are lacking.…”

“…Although it is not known when depletion of cellular Cbl stores and increases in MMA levels begin in the course of subnormal serum Cbl concentrations, MMA is currently considered the best indicator of Cbl status in cats . Studies examining biochemical Cbl deficiency in cats have focused on serum MMA concentration, and urine MMA concentration has been only sporadically reported . In humans, a linear relationship exists between serum and urine MMA concentrations .…”

Acquired urea cycle amino acid deficiency and hyperammonaemic encephalopathy in a cat with inflammatory bowel disease and chronic kidney disease

“…Hyperammonaemia can develop secondarily to different mechanisms: (1) acquired urea cycle amino acid deficiency; (2) cobalamin deficiency leading to accumulation of methylmalonic acid (MMA) and subsequent impaired uptake of ammonia into the urea cycle; 16 , 17 and (3) congenital deficiency in urea cycle enzymes such as ornithine transcarbamylase (OTC) deficiency. 18 The plasma amino acid profile in this case revealed several urea cycle amino acids deficiencies (citrulline, ornithine and arginine), which could be responsible for the hyperammonaemia.…”

“…The MMA status could not be assessed in this cat; however, the few feline cases reported in the literature with hyperammonaemic encephalopathy and high MMA concentration had low serum cobalamin concentrations. 16 , 17 …”