A good diagnostic workup allows the specialists to tailor treatment just for you. Below are the common tests used to diagnose PSC. Because misdiagnosis of PSC is common, you may have identified your disease through a long and frustrating route. Our brochure, Diagnosing PSC, covers in detail how the disease is determined. Click here for the brochure.
In diagnosing PSC the medical team will ask about your symptoms and may mention other diseases that can be associated with PSC. The physician may run blood tests to examine liver function. These tests are ALT (alanine aminotransferase, AST (aspartate aminotransferase, ALP (alkaline phosphatase, and GGT (gamma-glutamyltranspeptidase), and bilirubin.
Blood tests may also determine certain antibodies related to PSC. Because the disease is often associated with ulcerative colitis you may have a colonoscopy. In addition an ERCP or MRCP could be ordered. These tests look inside your bile ducts to see how narrowed they have become from PSC. Sometimes a liver biopsy and ultrasound are needed.
PSC is “staged” which means doctors can determine how far the disease has progressed.
Stages of PSC:
Liver Function Tests
If a liver problem is suspected, one of the first things your doctors will do is test your blood and examine the results of your liver function tests, or LFTs. If the readings are above the normal ranges you may have a liver problem, although several of the results may also be elevated if you have bone or cardiac problems. The tests don‘t indicate what type of liver problem you may have and further tests must be done.
The LFTs will include:
Gamma-glutamyl transferase (but you don’t have to bother with the big names, everyone uses GGT): This is an enzyme found mainly in the liver and is very sensitive to changes in liver function. If the liver is injured (as a consequence of liver disease), or there is an obstruction, GGT levels rise. It is the most sensitive liver enzyme for detecting bile duct problems. For most of us this will be elevated above the normal range because PSC involves inflammation and damage to the bile ducts.
Alanine aminotransferase: An enzyme mainly found in the liver. Elevations usually indicate bile duct problems.
Alkaline Phosphatase: An enzyme related to the bile ducts. It is typically elevated when there are bile duct problems, blockages, dominant strictures etc
None of these tests tell us about how the liver is functioning. But the tests that do tell us are:
This is the yellow breakdown product of red blood cells. They last for about four months after which the red hemoglobin breaks down into bilirubin. This is a function of the liver. The unconjugated bilirubin is carried to the liver. Sugars are attached and conjugated bilirubin is then passed into bile by the liver.
Elevated levels of bilirubin indicate that the liver is not performing this function well. Jaundice begins to appear when these levels increase in the blood. Normally the bilirubin is further broken down and excreted in the stools, which give them their characteristic color. But if you become jaundiced, the stools become grey (and the urine dark-red wine colored).
This measures the main protein made by the liver. If the liver is not making adequate amounts the test result will be below the normal range. Albumin is particularly important in regulating blood volume, carrying hormones, bile salts, iron, fatty free acids, etc.
PT and INR
Prothrombin time and international normalized ratio: This measures how long it takes plasma to clot with a usual reference range of 12-15 seconds. The clotting process is also a function of the liver.
This measures albumin and all other proteins in the blood including antibodies, which help to protect against infection.
In a similar way to blood pressure, these test results will vary over time and such things as vigorous exercise or high levels of tea consumption can affect them. If you keep a record you need to look at the trend over some months. The test result forms are easy to read because they include the normal ranges. Most of us notice that with high-dose Urso the elevations are reduced—and the results can go back to the normal range. There are a number of useful websites. See for example, Lab Tests Online (www.labtestsonline.org) There are many other blood tests that your doctors may order but these are the main ones. We should all be monitored on a regular basis.
Note: The lab tests material was written by Ivor S. and reprinted from the March, 2008 issue, 39, PSC News