Drug Induced Liver Disease (Hepatotoxicity)-Chapter 10- DIAGNOSIS OF DILD Part-2

Imaging studies

Imaging studies are used to exclude causes of liver pathology, after which a diagnosis can be made.

• Ultrasonography: Ultrasonography is inexpensive compared with CT scanning and MRI and is performed in only a few minutes. Ultrasonography is effective to evaluate the gall bladder, bile ducts, and hepatic tumors.

• CT scanning: CT scanning can help detect focal hepatic lesions 1 cm or larger and some diffuse conditions. It can also be used to visualize adjacent structures in the abdomen.

• MRI: MRI provides excellent contrast resolution. It can be used to detect cysts, hemangiomas, and primary and secondary tumors. The portal vein, hepatic veins, and biliary tract can be visualized without contrast injections.

Procedures 

Liver biopsy: Histopathologic evaluation remains an important tool in diagnosis. A liver biopsy is not essential in every case, but a morphologic pattern consistent with the expected pattern provides supportive evidence.

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Figure.10.1:- Diagnosis of Drug-Related Hepatotoxicity. There is no single test, including liver biopsy, that can be used to diagnose drug-related Hepatotoxicity. Other causes of liver injury must first be considered with the use of a combination of serologic tests, imaging studies, and clues from the patient’s history. CT denotes computed tomography, MRI magnetic resonance imaging, MRCP magnetic resonance cholangiopancreatography, ERCP endoscopic retrograde cholangiopancreatography, AST aspartate aminotransferase, ALT alanine aminotransferase, TIBC total iron-binding capacity, and A1AT  alpha₁-antitrypsin.

 

Key Elements of and Caveats in Assessing Cause in the Diagnosis of Drug-Related Hepatotoxicity.

Exposure to a drug must precede the onset of liver injury for diagnosis as drug-induced.

Caveat: The latent period for the onset of injury after drug use is highly

variable.

Disease as a cause of liver injury should be ruled out before concluding that hepatotoxicity is drug-related.

Caveat: Drugs taken concurrently should also be evaluated.

Injury may improve when administration of a drug is stopped (so-called dechallenge).

Caveat: Liver injury may first worsen for days or weeks. In severe cases, falling enzyme levels may indicate impending liver failure, not improvement, especially if accompanied by worsening function.

Liver injury may recur more rapidly and severely on repeated exposure, especially if immunologic in nature.

Caveat: Worsening on rechallenge may not occur if adaptive tolerance has occurred.