Increased serum bile acids (SBA) can be expected with hepatic, biliary or portal disorders that limit hepatic portal blood flow or hepatocellular uptake. Best clinicopathologic tests detecting those disorders remain controversial.

Results of paired SBA (pre- and 2 hours post-feeding) were retrospectively reviewed from samples obtained from animals undergoing bile acid (BA) testing because of suspected liver disease from two veterinary hospitals. The aim was to determine the frequency of altered values of fasting, postprandial and paired SBA, to evaluate if the clinical approach would be different depending on the selected test. SBA were sent off to an outside laboratory (IDEXX Barcelona) and measured by spectrophotometry with normal fasting value <10 µmol/L (a different cut-off of 25 µmol/L was also evaluated) and postprandial value <25 µmol/L.

The study included 484 samples from 392 dogs and 12 cats (178 females and 226 males). Median age was 5.4 years (0.17–13). Three feline breeds and 60 canine breeds were included.

Two hundred fifty-two paired SBA tests were considered as abnormal; among them, 175 (69.4%) fasting samples showed values >10 µmol/L (70 samples were 10–25 µmol and 105 samples were >25 µmol/L) and 201 (79.8%) postprandial samples were >25 µmol/L. In 131 tests (52.4%), only one BA value was altered; abnormal value was detected only with fasting value in 51 tests (20.4%) and only with postprandial value in 80 tests (32%). In 121 patients (48.4%), both fasting and postprandial values were increased. Among 70 animals with fasting value in 10–25 range, 37 had increased postprandial value. In 380 tests, fasting value was lower than postprandial value, but 101 tests showed higher fasting BA value.

Some authors have recently suggested that fasting BA can be a useful screening test (Straten 2015), but this study corroborates the higher value of paired SBA for this purpose, previously confirmed by others (Center 2011). If only fasting BA had been performed, and a higher cut-off had been selected (<20–25 µmol/L) as suggested by some authors, 52.8% of cases with fasting values in 10–25 range and abnormal postprandial values would have been missed; therefore, normal fasting value <10 µmol/L seems appropriate. Moreover, postprandial values were increased more often than fasting values; therefore, if just one BA can be performed, post-feeding could be the preferred test.

Fasting value exceeding the postprandial sample can occur, as shown in 1 out of 5 tests of this study. Although spontaneous gall bladder contraction may be responsible for it, if any value is abnormal, an hepatic abnormality is suggested (Lawrence 2017).

Disclosures

No disclosures to report