Tests of the liver
Tests of the liver
The work of the liver can be tested by doing blood tests, which are called liver function tests. These include measurement of:
Serum bilirubinBilirubin is a yellow-brown pigment that is a breakdown product of red blood cells, and it is present in the bile. In many liver diseases, the bilirubin level in the blood goes up, and this gives a yellow colour to the skin and the whites of the eyes, which is referred to as jaundice.
Liver enzymesThe serum levels of certain liver enzymes such as ALT and AST (also called transaminases) are raised when there is damage to liver cells. The levels of some others, called ALP (alkaline phosphatase) and GGT are raised when bile does flow properly.
Clotting testsIn chronic liver disease, the clotting of blood may be affected, and this shows up by an increase in what is called the Prothrombin time, or the INR.
Serum albuminIn chronic disease, the liver’s ability to make proteins can be diminished, and this shows up by a fall in the serum albumin level.
The anatomy of the liver (i.e. is the shape of the liver altered in any way, or are there tumours within it) can be assessed by doing scans like:
UltrasoundThis involves running sound waves through the abdomen and picking up abnormal echoes. It is painless, quick, relatively inexpensive, and does not involve radiation. The accuracy is however very much dependent on who does and interprets the scan.
CT (computed tomography)This involves lying in a scanner that resembles a giant polo-mint while the machine takes complex x-ray pictures of one’s insides, which are then seen as serial horizontal or vertical slices through the body. Injection of contrast media into the veins is often done at the time of the scan to sharpen the images.
MR (magnetic resonance)Somewhat similar to CT, but uses a different principle, and no radiation. The scanner is more like a small tunnel that one has to lie in, and the scan cannot be done on people who have metal implants in their bodies. MR can be used to obtain a picture of the bile duct and the pancreatic duct, and this called MRCP.
Nuclear medicine scansSome of these scans actually test the function of the liver rather than its structure. For example a HIDA scan checks the speed at which the liver takes up a substance from the blood and releases it into the bile. Other nuclear medicine tests (such as PET scans) can show up tumours.
Endoscopy and ERCPIt is possible for doctors to pass a camera that is contained within a flexible tube, down the throat into the stomach and duodenum (the first part of the bowel), and look at the inner lining of these organs. This is called Endoscopy or Oesophago-gastro-duodenoscopy (OGD). In ERCP, after an initial Endoscopy, dye is injected into the bile duct and pancreatic duct so that they show up on x-rays. You can download an information sheet that will tell you more about these tests.
Liver BiopsyThis involves passing a needle through the skin into the liver and removing a tiny core of liver tissue for testing. It is done under local anaesthesia, usually in the x-ray department. It can also be done by passing a catheter though one of the veins in the neck, and this is called a Transjugular liver biopsy. You can download an nformation sheet that will tell you more about liver biopsy.