[Utility of analytical parameters in the diagnosis of liver disease].

Liver function tests include biochemical parameters (AST, ALT, GGT or Alkaline phosphatase), bilirubin and albumin levels and coagulation tests as prothrombin activity. These tests are commonly used in the routine screening even in symptomatic as in asymptomatic patients, and the right evaluation of the results is of vital importance. Cytolytic elevation in serum aminotransferases: In mild chronic elevation pharmacological toxicity, viral hepatitis, alcoholic and non-alcoholic fatty liver disease and hemochromatosis, should be excluded. Cholestatic elevation os serum enzymes: The first option should be to establish the origin of the alkaline phosphatase elevation, with the evaluation of the GGT levels to confirm the hepatic origin. The next step should be to distinguish the presence of an extrahepatic (biliary obstruction) or intrahepatic (PBC, PSC, drugs, etc) cholestasis, in these cases the most important test should be the abdominal ultrasound, in order to evaluate the biliary system. Hyperbilirubinemia: Non conjugated hyperbilirubinemia (hemolysis, ineffective erythropoiesis, Gilbert or Criggler-Najjar syndromes) and conjugated hyperbilirubinemia, an unusual situation in which Rotor and Dubin-Johnson Syndromes should be considered. The evaluation of albumin and prothrombin levels evaluates the hepatic function per se, allowing to differentiate between acute and chronic diseases. At present, there are not prospective studies to evaluate the efficacy of the liver function tests. To carry out a complete medical history, an appropriate physical examination and the appropriate application of non-invasive diagnostic tests (serology, iron levels, autoimmunity or abdominal ultrasound) allow to perform a right diagnosis in most patients, making more complex tests, including liver biopsy, secondary.