MedicineNet.com
About Us | Privacy Policy | Site Map
November 24, 2009
MedicineNet home Picture Slideshows Diseases and conditions Symptoms and signs Procedures and tests Medications Health and Living Picture Image Collection MedTerms medical dictionary
Font Size
A
A
A

Primary Biliary Cirrhosis (cont.)

In this Article

What is the role of blood tests?

The key blood test abnormality in PBC and all liver diseases associated with cholestasis is an elevated alkaline phosphatase enzyme level in the blood. The finding of a concurrent elevation of the gamma glutamyl transpeptidase (ggt) blood level proves that the elevated alkaline phosphatase is from the liver, rather than from bone (another source of alkaline phosphatase). Other liver enzymes, such as aspartate aminotransferase (AST) and alanine aminotransferase (ALT), may be either normal or only slightly elevated at the time of diagnosis. As the duration of disease increases, both of these liver enzymes (the aminotransferases) usually become elevated to a mild to moderate degree, while the alkaline phosphatase can become very high. For more information about liver blood tests, please read the Liver Blood Tests article.

Other blood tests may also be helpful in the diagnosis of PBC. For example, serum immunoglobulin M (IgM) is frequently elevated. Also, just about all patients with cholestasis develop increased cholesterol levels (as noted previously), and some also develop elevated triglycerides. Moreover, testing the levels of these fats (lipids) can identify patients who might form cholesterol deposits in the skin or nerves. (See the section on xanthomas above.)

What is the role of testing for antimitochondrial antibodies?

AMA are detectable in the serum in 95 to 98% of patients with PBC, as noted earlier. The most economical test for AMA applies diluted samples of a patient's serum onto tissue sections from rat stomach or kidney in the laboratory. (Remember that the mitochondria are present in all cells, not just the cells of the liver and bile ducts.) Serum antibodies that attach (bind) to mitochondrial membranes within the tissue cells can then be observed with a microscope. The most dilute sample of serum showing this binding reaction is reported, using the term titer. The titer indicates the most dilute serum sample that reacts with the tissue mitochondria. A higher titer means there is a greater amount of AMA in the serum.

The AMA titers in PBC are almost universally greater than or equal to 1 to 40. This means that a serum sample diluted with 40 times its original volume still contains enough antimitochondrial antibodies to be detected in the binding reaction. A positive AMA with a titer of at least 1:40 in an adult with an elevated alkaline phosphatase is highly specific for a diagnosis of PBC. The antigen recognized by AMA in patients with PBC is now known to be PDC-E2 and is also often referred to as the M2 antigen, as discussed earlier. So, newly developed tests for antibodies that bind to PDC-E2 are more specific and are now available to confirm the diagnosis of PBC.

It is noteworthy that approximately 20% of patients with AMA also have antinuclear (ANA) and/or anti-smooth muscle (SMA) autoantibodies in their blood. The ANA and SMA are more characteristically found in a disease called chronic autoimmune hepatitis. It turns out that patients who have persistently undetectable AMA but otherwise have clinical, laboratory, and liver biopsy evidence of PBC, all have either ANA or SMA. These patients have been referred to as having AMA-negative PBC, autoimmune cholangiopathy, or autoimmune cholangitis. The natural history, associated diseases, laboratory test abnormalities, and liver pathology are indistinguishable between the AMA-positive and AMA-negative patients. Thus, it seems inappropriate, for now at least, to classify this AMA-negative disease as different from PBC. Accordingly, this situation should be referred to as AMA-negative PBC. Rarely, some other patients appear to concurrently have features of both PBC and chronic autoimmune hepatitis. Such patients are said to have an overlap syndrome.



Next: What is the role of imaging tests? »

Primary Biliary Cirrhosis - Symptoms Experienced

The MedicineNet physician editors ask:

Please describe the symptoms of your primary biliary cirrhosis.

Comment submissions for this question have ended. Patient Discussions FAQs
See 21 Viewer Comments

View Comments


Printer-Friendly Format  |  Email to a Friend


Suggested Reading by Our Doctors
MedicineNet Doctors
  • colchicine, Colchicine - Read about colchicine, a drug prescribed for the pain of gouty arthritis. Side effects, drug interactions, dosage, and preagnancy information is also included in the information.
  • Liver Blood Tests - Learn about liver blood tests used to detect liver damage disease such as fatty liver, cirrhosis, hepatitis, Tylenol liver damage, and more. This includes measuring the aminotransferases enzymes (AST and ALT levels)
  • Liver Cancer - Get information on liver cancer, its symptoms, causes, diagnosis, staging, prognosis, treatment, and prevention.

Latest Medical News


Women's Health

Find out what women really need.


Are you Depressed? Take the Quiz

Your Guide to Symptoms & Signs: Pinpoint Your Pain












Health categories:

Slideshows | Diseases & Conditions | Symptoms & Signs | Procedures & Tests | Medications | Health & Living | News & Views | Medical Dictionary

Popular health centers:

Allergies | Arthritis | Cancer | Diabetes | Digestion | Healthy Kids | Heart | Men's Health | Mental Health | Women's Health | More...

Publications:

ePublications (PDFs) | XML News via RSS | Audio Podcasts | Email Newsletters

MedicineNet.com:

About Us | Privacy Policy | Site Map | WebMD® | Medscape® | eMedicine® | eMedicineHealth® | RxList®

This website is certified by Health On the Net Foundation. Click to verify. This site complies to the HONcode standard for trustworthy health information:
verify here.

©1996-2009 MedicineNet, Inc. All rights reserved. Notices and Legal Disclaimer.
MedicineNet does not provide medical advice, diagnosis or treatment. See additional information.