Diagnosis of Intrahepatic Cholestasis
Diagnostic Approach
- The American Association for the Study of Liver Diseases recommends a sequential algorithmic approach to diagnose intrahepatic cholestasis, starting with a detailed clinical history and abdominal ultrasonography to exclude extrahepatic obstruction, followed by tests for antimitochondrial antibodies (AMA) and, if negative, magnetic resonance cholangiopancreatography (MRCP) and liver biopsy when the diagnosis remains uncertain 1, 2.
- The European Association for the Study of the Liver suggests that the diagnosis of intrahepatic cholestasis should involve a step-wise approach, including confirmation of biochemical abnormalities, evaluation of the patient's history, and performance of imaging studies such as ultrasonography and MRCP 3, 4.
Biochemical Confirmation and Initial Evaluation
- The American College of Gastroenterology recommends confirming an elevation of alkaline phosphatase (FA) >1.5 times the upper limit of normal (ULN) with gamma-glutamyltransferase (GGT) >3 times ULN to establish a hepatobiliary origin 5.
- The GGT elevates earlier and persists longer than FA in cholestatic disorders, but isolated GGT elevation lacks specificity and may reflect enzyme induction by alcohol or drugs 3, 4, 5.
Imaging Studies
- The American Institute of Ultrasound in Medicine suggests that ultrasonography is the first mandatory imaging step to differentiate intrahepatic cholestasis (non-dilated ducts) from extrahepatic cholestasis (dilated ducts) 1, 5, 6.
- MRCP has a sensitivity of 96-100% for detecting stones in bile ducts and should be used as the next diagnostic step in patients with intrahepatic cholestasis of unknown cause 1, 2, 5, 6.
Liver Biopsy
- The American Association for the Study of Liver Diseases recommends performing a liver biopsy when the diagnosis remains uncertain after negative AMA and MRCP 1, 2.
- A biopsy of adequate quality should contain ≥10 portal fields due to the high degree of sampling variability in patients with small bile duct disease 1, 2.
Classification of Biopsy Findings
- Biopsy findings should be classified into three categories: disorders involving bile ducts, disorders not involving bile ducts, and hepatocellular cholestasis with minimal histological abnormalities 1, 2.
Genetic Testing
- The European Association for the Study of the Liver suggests that genetic testing for ABCB4 should be considered in patients with negative AMA and biopsy findings compatible with primary biliary cirrhosis (PBC) or primary sclerosing cholangitis (PSC) 1.
Common Causes of Intrahepatic Cholestasis
- The American College of Gastroenterology lists the common causes of intrahepatic cholestasis, including hepatocellular cholestasis, cholangiocytic cholestasis, and infiltrative disorders 3, 4, 7.
Common Pitfalls to Avoid
- The American Gastroenterological Association advises against performing diagnostic endoscopic retrograde cholangiopancreatography (ERCP) as the first-line investigation, and instead recommends using MRCP or endoscopic ultrasonography (EUS) to avoid unnecessary complications 1, 2, 5, 6.
- The European Association for the Study of the Liver warns against assuming that isolated GGT elevation indicates cholestasis, as it may simply reflect enzyme induction 3, 4, 5.