Assessment of liver damage
One way of assessing if liver cells are dying is by testing the level of the liver enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the blood. This is not particularly reliable as in most cases of chronic hepatitis C infection the liver function tests tend to fluctuate. Over the space of just a few days the results can vary from normal to noticeably raised. Raised ALT levels are present in around two-thirds of those infected while the remaining third show no evidence of elevated levels at all. These traditional liver function tests are not very effective indicators of liver damage in chronic hepatitis C. Currently the most reliable way to assess the extent of liver damage is by liver biopsy, however a Fibroscan or other non-invasive techniques will be sufficient in most cases.
There are also some new blood tests that are starting to be used in the UK as markers of liver damage. These are made by a variety of different companies and are marketed under names such as Fibrotest, Fibrosure, and Actitest. Another way some doctors determine the presence of cirrhosis is by looking over time at the AST/ALT ratio. It seems that if the AST is consistently higher than ALT or equal to it this is highly suggestive of cirrhosis.
At present the most accurate way to check the extent of liver damage is by biopsy. A liver biopsy is a test in which small pieces of liver tissue are removed and examined under a microscope. This is done via a long needle inserted usually between the 8th and 9th ribs under the right arm. The tissue will be assessed to see the extent of inflammation and fibrosis (as well as revealing other abnormalities such as damage to bile ducts and the presence of fat).
Fibroscan is a non-invasive test using a sound wave to measure the elasticity of the liver and is being used more and more in the UK. As damage to the liver increases, so it becomes stiffer. The stiffer or less elastic the liver, the faster the sound wave travels. The Fibroscan has been shown to be accurate in measuring little or no damage and in measuring cirrhosis. It has been less accurate at distinguishing intermediate degrees of fibrosis.
The machine is calibrated from 0 to 75, with around 4 representing no liver damage, 4-9 increasing amounts of fibrosis, 9.5 - 10.5 severe fibrosis, 11 and above cirrhosis.
Its advantage over a biopsy is that it is quick and completely painless. This is because the probe is simply placed against the skin and nothing is inserted into the body. It is also capable of distinguishing differing degrees of cirrhosis as 80% of its entire range measures cirrhosis. For example, a score of 30 indicates existing or imminent decompensation