3 alpha-hydroxylated bile acid profiles in clinically normal cats, cats with severe hepatic lipidosis, and cats with complete extrahepatic bile duct occlusion

Concentrations of 3 alpha-hydroxylated bile acids were measured in serum and urine of clinically normal (healthy) cats (n = 6), cats with severe hepatic lipidosis (n = 9), and cats with complete bile duct occlusion (n = 4). Bile acid concentrations were measured by use of a gradient flow high-performance liquid chromatography procedure with an acetonitrile and ammonium phosphate mobile phase and an in-line postanalytic column containing 3 alpha-hydroxysteroid dehydrogenase and a fluorescence detector. Specific identification of all bile acid peaks was not completed; unidentified moieties were represented in terms of their elution time (in minutes). Significant differences in serum and urine bile acid concentrations, quantitative and proportional, were determined among groups of cats. Cats with hepatic lipidosis and bile duct occlusion had significantly (P greater than or equal to 0.05) greater total serum and urine bile acids concentrations than did healthy cats. The proportion of hydrophobic bile acids in serum, those eluting at greater than or equal to 400 minutes, was 1.9% for healthy cats, 3.3% for cats with lipidosis, and 5.4% for bile duct-obstructed cats. Both groups of ill cats had a broader spectrum of unidentified late-eluting serum bile acids than did healthy cats; the largest spectrum developed in bile duct-occluded cats. The trihydroxy-to-dihydroxy serum bile acids ratio was 8.8:1 for healthy cats; 24.1:1 for cats with lipidosis: and 20:1 for cats with bile duct obstruction. There was a paucity of glycine-conjugated bile acids in all cats and small quantities of secondary bile acids in ill cats. A significantly (P < 0.05) smaller proportion of unconjugated primary bile acids was detected in sera from ill cats. Serum taurolithocholic acid was detected only in small quantities in cats of each group. There was significantly increased quantity, but lower proportion, of trihydroxy-cholestanoic acid in serum from ill cats, compared with healthy cats. A significantly (P < 0.05) greater proportional amount of unidentified moieties eluting at 130 and 277 minutes was detected in urine of cats with hepatic lipidosis; we believe that the unidentified moiety eluting at 277 minutes is tau- tauroallocholic acid. Large proportional amounts of taurocholic and cholic acids were detected in urine of all cats, but ill cats had significantly (P < 0.05) greater quantities (quantitatively and proportional). Ill cats had significantly (P < 0.05) more taurocholic than cholic acid in urine. Because taurine is an essential amino acid for cats and is a necessary daily dietary constituent, large urinary losses of taurine in conjugated bile acids may further compromise the health of anorectic cats with severe hepatic lipidosis.