Primary Biliary Cirrhosis (cont.)

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What are risk factors for PBC?

Identification of risk factors for developing PBC should be an important priority, but astonishingly little research has been done in this area. A 2002 survey used questions from the National Health and Nutrition Examination Survey of the U.S. government. This survey compared the answers of 199 patients with PBC with those of 171 siblings and 141 friends of the patients. As anticipated, the patients with PBC were predominantly women (10 to 1 women to men), and the average age was 53 years.

The patients reported having had a high frequency of other autoimmune diseases, including sicca syndrome in 17.4% and Raynaud's phenomenon in 12.5%. Interestingly, 6% reported that at least one other family member had PBC. Statistical analysis showed that the risks of developing PBC for patients compared to friends as controls were:

  • 492% greater for having had other autoimmune diseases
  • 204% greater for having smoked cigarettes
  • 186% greater for having had tonsillectomy
  • 212% greater among women for having had urinary tract infections or vaginal infections.

Similar increased risks were found for the PBC patients when they were compared to siblings without PBC.

How is PBC diagnosed?

The diagnosis of PBC is established by the results of several types of tests. These include blood tests, serum autoantibody testing, ultrasound imaging of the liver, and liver biopsy.

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.)

Medically Reviewed by a Doctor on 1/9/2014

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