Diagnosis of Progressive Familial Intrahepatic Cholestasis (PFIC)

Summary Diagnostic Tests

There are different diagnostic tests, which are used to identify PFIC and potentially determine which type of PFIC is present.

These are blood tests which may help to assess the general condition of the liver and can provide some information as to the type of PFIC. One particularly useful test is gamma GT (GGT), which is a type of liver enzyme which may help to distinguish between the types of PFIC. The GGT levels in the blood are low or normal in FIC1 and BSEP deficiencies but raised in MDR3 deficiency. Markers of liver injury (ALT and AST) may provide some differentiation between FIC1 and BSEP disease, these enzymes are often lower in FIC1 disease.

These are more specialized blood and urine tests. Children with PFIC will have quite elevated levels of bile acids in blood – 10 to 20 times the normal bile acid concentration. If bile acids are not elevated this may suggest a problem making bile acids (bile acid synthesis disease), which may be identified by looking at bile acids in the urine.

A small piece of liver tissue is extracted with a small needle, and then examined under the microscope. An open surgical operation is not usually needed. Results from the liver biopsy are used to help make the diagnosis, to assess the severity of the disease and to advise about the future (prognosis).

Genetic testing can reveal exactly which gene is mutated and provide information about the severity of the disease. This type of testing can therefore identify the subtype of PFIC. Genetic testing can be done with a blood sample, and involves extracting the code of the PFIC genes from the DNA in the blood. Note that these tests are expensive, might not be covered by insurance and are not available in all countries.

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