Autoimmune diseases of the liver may remain inconspicuous for a long time without symptoms or with very non-specific symptoms such as fatigue or arthralgia. Hence, the disease is often diagnosed only at a late stage – even though early treatment might prevent permanent damage. Therefore, it is important to correctly interpret the early signs of an autoimmune liver disease and to perform further tests.
Elevated liver tests
Often, elevated liver enzyme values are the first sign of an autoimmune liver disease. Liver enzymes are proteins that especially exist in liver cells. They can be are released into the blood upon damage of the cells and can then be measured in a blood test. The most important liver enzymes are:
- GOT (glutamate oxaloacetate transaminase), also known as AST (aspartate aminotransferase)
- GPT (glutamate pyruvate transaminase), also known as ALT (alanine aminotransferase)
- GGT (gamma glutamyltranferase)
- AP (alkaline phosphatase)
These “liver tests” (also called “liver function tests” (LFTs)) are also elevated in many different diseases of the liver and hence can easily be misinterpreted. If only slightly elevated and if no other symptoms are reported these test results are often considered to be not important.
However, especially a slight elevation of the liver tests may point to an autoimmune cause. Hence, they should always lead to further tests with regard to an autoimmune disease. With such an approach, many diseases can be diagnosed at an early stage and may then be treated successfully.
In autoimmune liver diseases the own immune system targets the body’s own cells in the liver. The immune system during this process produces so-called autoantibodies. Autoantibodies are specialized proteins that attach themselves to special parts of the cells and damage these. Most autoantibodies are part of other autoimmune diseases and hence are no highly specific sign, but hint at the correct diagnosis.
In some patients, so-called SLA/LP autoantibodies may occur. Their existence is a clear sign for an autoimmune hepatitis since they can almost never be found in any other disease.
Tissue sample (biopsy)
If an autoimmune liver disease is suspected, an examination of the liver tissue – the liver biopsy – is necessary in almost all cases. Under local anaesthetic and ultrasound control a special needle will be very briefly inserted into the liver. Sometimes, patients may be given a sedative so that the examination is not stressful for the patient.
The needle is then withdrawn from the liver and contains liver tissue which is then examined under the microscope. Specific structures of the liver cells, the bile ducts and the connective tissue will hint at an autoimmune liver disease and at its type, and may exclude other causes of liver disease.
Alternatively, a minilaparoscopy under local anaesthetic may be conducted. A small tube is inserted near the umbilicus allowing the liver surface to be evaluated, and a biopsy can be taken. This is one of the advantages of this technique in autoimmune liver diseases: typical changes are spread irregularly over the organ. Minilaparoscopy allows a biopsy also in patients with an increased bleeding tendency because potential bleedings can be stopped by coagulation immediately under visual control.
Diagnosis of an autoimmune liver disease is not medical routine. As in many other diseases, the diagnosis is the sum of various symptoms and findings. Experience in these rather rare diseases is advantageous in making the diagnosis. It is most important to consider an autoimmune liver disease in the differential diagnosis of unexplained liver disease, and to start further diagnostic procedures accordingly. The right diagnostic intuition may prevent permanent liver damage and thus may be of immeasurable value for the patient’s life.