Hyperammonemia in azotemic cats

Abstract

Objectives Hyperammonemia occurs in cats with hepatobiliary and nutritional (cobalamin and arginine deficiency) disorders, and has also been documented in four cats with renal azotemia. We hypothesized that in cats with renal azotemia, fasting hyperammonemia would correlate with indices of worsening kidney function, and would be independent of cobalamin, potassium, systemic inflammation or urinary tract infection (UTI) with urease-producing bacteria. Methods A fasted blood sample was prospectively collected for ammonia and cobalamin analysis from 18 client-owned cats with renal azotemia (creatinine [Cr] ⩾1.6 mg/dl, urine specific gravity <1.030 or documentation of historical chronic kidney disease [CKD]). Correlations between blood ammonia and selected biochemical parameters were analyzed using Pearson’s correlation coefficient. Results Seven castrated males and 11 spayed females with a median age of 12 years (range 4–19 years) were enrolled. Ten of 18 (56%) cats presented for acute kidney injury (AKI) or acute on chronic kidney disease (AoCKD), and 8/18 (44%) presented for progressive CKD. The median Cr was 5.9 mg/dl (range 1.9–24.7 mg/dl). Hyperammonemia was documented in 4/18 (22%) cats, with a median of 95 µmol/dl (range 85–98 µmol/dl), and all four of these cats were classified as AKI/AoCKD. Blood ammonia concentrations had a significant moderate positive correlation between blood urea nitrogen (BUN) ( r = 0.645, P = 0.003), Cr ( r = 0.578, P = 0.012) and serum phosphorus ( r = 0.714, P = 0.0009) but not with cobalamin, potassium or white blood cell count. No cats had UTIs with urease-producing bacteria. Conclusions and relevance A correlation exists between blood ammonia and BUN, Cr and phosphorus in cats with renal azotemia. Future studies are warranted in a larger population of cats to determine the true prevalence, etiology and potential therapeutic effect of medical management of hyperammonemia on long-term prognosis in cats with kidney disease.

Development of a reference interval for urinary ammonia‐to‐creatinine ratio in feline patients

“…In humans, measurement of urinary ammonia excretion has been shown to be of value in assessing the response of the kidneys to acid challenges in different disease states 4,5 . Few studies have been published referencing alterations in urine ammonia in cats with CKD 7,12 . Having a reference interval for UACR in healthy cats will be useful in evaluating UACR in diseased populations.…”

“…4,5 Few studies have been published referencing alterations in urine ammonia in cats with CKD. 7,12 Having a reference interval for UACR in healthy cats will be useful in evaluating UACR in diseased populations. If certain disease states, such as CKD, are found to have UACR values outside of the RI for clinically healthy cats, UACR could become a clinically relevant value in assessing prognostic information and guiding clinical decision-making.…”

KID-T, a unique polyherbal extract, improves feline patients with azotemia and uremia: A pilot study

“…Blood ammonia is converted to urea in the liver via the urea cycle, which is eventually evaluated in the blood as blood urea nitrogen. Therefore, decreasing the ammonia concentration in the blood is essential to lower blood urea nitrogen levels in patients with kidney disease (Narasimhan et al, 2001;Imran et al, 2012;Adagra et al, 2015;Carvalho et al, 2021). Azotemia and uremia in patients with hyperammonemia are factors that aggravate kidney disease (Imran et al, 2012;Adagra et al, 2015;Carvalho et al, 2021).…”

“…Therefore, decreasing the ammonia concentration in the blood is essential to lower blood urea nitrogen levels in patients with kidney disease (Narasimhan et al, 2001;Imran et al, 2012;Adagra et al, 2015;Carvalho et al, 2021). Azotemia and uremia in patients with hyperammonemia are factors that aggravate kidney disease (Imran et al, 2012;Adagra et al, 2015;Carvalho et al, 2021). After administration of KID-T, ammonia levels, which were higher than the normal range before administration, decreased, suggesting that KID-T improves hyperammonemia and particularly contributes to liver detoxification and kidney toxin excretion functions.…”

Relationship between a plant‐based ‘vegan’ pet food and clinical manifestation of multiple nutrient deficiencies in two cats

“…The higher requirement for arginine in cats is also considered as one of its metabolic idiosyncrasies. Cats have, in fact, a low capacity of synthesising arginine from its precursors ornithine and citrulline (low enzymatic activity of pyrroline-5-carboxylase synthase and ornithine aminotransferase in the intestinal mucosa) coupled with the aforementioned inability to downregulate the liver-enzymes activity; hence, they need a high dietary concentration of arginine (Carvalho et al, 2020;Morris, 2002a). Near-adult cats fed a single arginine-free meal quickly develop hyperammonaemic encephalopathy due to the role of this amino acid in the conversion of ammonia into the less toxic urea (urea cycle inside liver's mitochondria) (Morris & Rogers, 1978).…”