Thanks to all the vets who joined us last month for the second of our 2019 evening seminars, which was focused on the diagnostic approach to liver diseases and was given by our colleague Selda Curtseit. Below is a short summary of one of the talks with the main key points.
Next BattLab evening seminar will be held on September 21st and will be about urinalysis. Details will follow in next newsletters.
DIAGNOSTIC APPROACH TO LIVER DISEASES – a few take home messages:
Laboratory tests play an important role in the recognition and diagnosis of canine and feline hepatobiliary diseases. These tests have several objectives that include determining whether hepatobiliary disease is present, if liver disease is primary or secondary, the definitive type of liver disease, and monitoring response to therapy or disease progression.
The main challenge in diagnosing hepatobiliary disease is the consequence of the large functional reserve of the liver. Thus, clinical signs and laboratory changes occur after a marked loss of functional hepatic tissue.
- Alanine aminotransferase (ALT) is the gold-standard marker for hepatocellular injury. In cats, because of short half-life of ALT activity, even mild elevations are considered to be clinically relevant.
- Aspartate aminotransferase (AST) starts to increase rapidly and mutually in parallel with ALT in liver disease. However, muscle damage and haemolysis can also cause considerable increases in AST activity. Therefore, AST is considered less liver specific than ALT.
- Alkaline phosphatase (ALP) and Gamma-glutamyltransferase (GGT) are both cholestatic markers. The main use of ALP is as sensitive indicator of cholestasis (it will increase before bilirubin), however it is non-specific because, in dogs, corticosteroids (exogenous/endogenous) induces production of this enzyme, with subsequent increases in serum or plasma activity. Elevation of ALP may also be observed in selected neoplastic processes (e.g. osteosarcoma, mammary tumours), bone fracture healing, hyperparathyroidism, and in young animals. Idiopathic elevations in ALP have been reported in Scottish Terrier and Siberian Husky dogs.
- Serum bile acids (SBA) provides useful information about the portal venous circulation and hepatic function. Fasting SBA concentrations of >20 μmol/L and postprandial SBA concentrations of >25 μmol/L are very specific for liver disease in dogs and cats. Fasting SBA concentrations between 5–20 μmol/L must be interpreted in light of other clinical and lab findings. Portosystemic shunt (CPSS) are usually associated with marked increase of both pre- and post-prandial bile acids.
- After CPSS ligation, SBA may remain increased for approximately 5 years. Values of SBA <50 umol/L in dogs with complete CPSS ligation are of minimal clinical significance. However, if pre-prandial values are persistently markedly increased, abdominal ultrasound is recommended to check for residual shunting or multiple acquired shunts.
- Cytological evaluation in hepatobiliary disease is most effective in the diagnosis of fatty change, neoplastic disease and least effective in inflammation, dysplasia, hyperplasia. Histopathology is preferred in those cases.
At BattLab we offer a wide variety of biochemistry tests. For more information don’t hesitate to contact us.
