Liver Function Tests

Liver is an organ of your body that carries out nearly 500 functions. It is impossible for us to test for each of these functions. The freely available tests at all laboratories are usually called liver tests or liver function tests which are ideally a screening test and helps the doctor decide a direction for the direction of next investigation. Liver disease per se develops symptoms very late. When they develop symptoms, the liver damage is often quite severe. The only ways to detect abnormalities of liver before the development of symptoms are the above battery of tests.  They not only tell us the reason for liver abnormalities, they also help to decide the severity. The tests include bilirubin, ALT, AST, ALP, GGT, Proteins, Albumin and Prothrombin Time. These tests are bundled together in different combinations are known as liver function tests. It is based on these tests doctors can gauze what is wrong with your liver.

The term jaundice is derived from French “jaun” (yellow). Bilirubin is a substance responsible for jaundice. Bilirubin is measured as total, direct and indirect. They differentiate between patients with predominant type of jaundice. Indirect bilirubin or unconjugated hyperbilirubinemia could be due to Gilbert’s syndrome, hemolysis, ineffective erythropoiesis or due to resorption of large hematoma in post-operative period. A series of investigations can then help differentiate thes conditions. Direct hyperbilirubinemia is suggestive of liver disease (viral, alcohol related, drug induced, autoimmune or metabolic etiology) or obstructive jaundice (stone, tumour or stricture) or uncommonly intrahepatic cholestatic disease (primary biliary cirrhosis or primary sclerosing cholangitis).  Hereditary direct hyperbilirubinemia due to Rotor syndrome or Dubin-Johnson syndrome is rarely encountered.

The transaminase (AST, ALT) and serum ALP elevations in patients with jaundice also give clue to possible etiology. They are markers of ongoing liver cell damage. Most commonly cause of these elevations currently in city of Ahmedabad is fatty liver. However other diseases also need to be ruled out when an individual has elevated levels of these enzymes. According to current data, the normal upper limit of ALT in males is 30 while those in females is 19 IU/L. Patients who have predominant increase in AST and ALT without significant elevation of alkaline phosphatase require further investigations for hepatocellular jaundice. These include tests for viral markers, autoimmune markers and tests for metabolic disorders.The range of elevation of AST and ALT may also give clue to possible etiology. The transaminase levels of 1000 to 2000 typically occur in acute viral hepatitis. Levels of up to 2 to5 times the upper limit of normal may occur in chronic viral hepatitis, drug induced hepatitis, autoimmune hepatitis or alcoholic hepatitis. Ratio of SGOT to SGPT of more than 2:1 is typical of alcoholic hepatitis. Transaminases levels of over 3000 to 5000 are seen in toxic hepatitis and in patients with circulatory shock.

ALP is indicative of obstructive etiology and an ultrasound is the next step to exclude some pathology in the bile duct or gall bladder.

In patients with severe liver disease prothrombin time becomes abnormal and in patients with long standing liver disease albumin levels start to come down.

If you have a abnormal test on routine screening, do not ignore it and meet your liver specialist right away. As described, liver disease produces symptoms very late.