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274 - Laboratory diagnosis of autoimmune diseases of the hepatobiliary tract

Autor(s): N. Bizzaro

Issue: RIMeL - IJLaM, Vol. 6, N. 4, 2010 (MAF Servizi srl ed.)

Page(s): 274 - 80

The autoimmune cholangiopathies comprehend chronic disorders of the intrahepatic (primary biliary cirrhosis, PBC) and of the intra- and extrahepatic (primary sclerosing cholangitis, PSC) biliary ducts. However, while PBC is a prototypic autoimmune disease, the inclusion of PSC among the autoimmune diseases is still controversial since criteria are only in part fulfilled and PSC should be more properly considered an immune-mediated disorder. PBC is a chronic and progressive disease of unknown etiology, characterized by inflammation and progressive destruction of the small-to-medium bile ducts, which leads to cholestasis. Cholestasis over a long period of time may cause scarring and cirrhosis. PBC is usually diagnosed in patients between the ages of 35 to 60 years and about 90% of patients are women. Environmental factors such as infections, may trigger the disease in genetically predisposed individuals. Due to widespread laboratory screening, more than 60% of newly diagnosed PBC patients now are asymptomatic. The key blood test abnormality in PBC is an elevated alkaline phosphatase and gamma glutamyl transpeptidase enzyme level. Other liver enzymes, sferase, may be either normal or only slightly elevated at the time of diagnosis. The presence of high-titer anti-mitochondrial antibodies is a distinctive feature of the disease. Ursodeoxycholic acid is the only accepted treatment for PBC. PSC is a chronic cholestatic liver disease of unknown etiology characterized by inflammation and stenosis of the intrahepatic and extrahepatic biliary tree. The disease is usually progressive, leading to cirrhosis, portal hypertension, and liver failure. The diagnosis is based on a combination of clinical features and cholestatic biochemical profile, along with typical cholangiographic abnormalities, and confirmed by liver histology findings. Multiple autoantibodies have been detected in the serum of PSC patients but none are sufficiently sensitive or specific to have clinical utility. However, the presence of P-ANCA is frequent and may be related to the close association of PSC with ulcerative colitis which is present in 70-80% of PSC patients. Other antibodies, such as antinuclear, anti-smooth muscle, anticardiolipin and rheumatoid factor are less prevalent. Anti-mitochondrial antibodies are typically absent. There is no proven medical therapy leaving liver transplantion as the only option for end-stage PSC.

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