Diagnostic Approach for Elevated ALT/AST

Understanding the Clinical Context

The American College of Radiology states that contrast-enhanced CT has >90% sensitivity for detecting biliary obstruction and can accurately determine both the site and cause of obstruction 3, 4, 5
If the CT is normal during the acute spike, biliary obstruction and structural hepatobiliary pathology have been effectively excluded, according to the American College of Radiology 3, 5
HIDA scanning is designed to diagnose cystic duct obstruction in acute cholecystitis, not to evaluate hepatocellular injury, as recommended by the Clinical Infectious Diseases guidelines 1, 6

The American Gastroenterological Association recommends performing serologic testing to exclude common hepatic diseases (viral hepatitis, autoimmune hepatitis, hemochromatosis, Wilson's disease, alpha-1 antitrypsin deficiency) 7
The American Gastroenterological Association suggests reviewing all medications, supplements, herbs, and over-the-counter drugs as potential causes of drug-induced liver injury 7
The American Gastroenterological Association advises assessing alcohol consumption and metabolic risk factors (obesity, diabetes, hyperlipidemia) for non-alcoholic fatty liver disease 7

The Clinical Infectious Diseases guidelines state that first-line imaging is ultrasound for suspected acute cholecystitis (sensitivity 73%, specificity 83%) 1, 8
If ultrasound is equivocal, the Clinical Infectious Diseases guidelines recommend proceeding to CT scan as the next step in non-pregnant adults 1, 6
HIDA scan is reserved for when BOTH ultrasound AND CT are equivocal/non-diagnostic but clinical suspicion for acute cholecystitis persists, according to the Clinical Infectious Diseases guidelines 1, 2, 6

For persistent or markedly elevated ALT/AST with normal CT, the American Gastroenterological Association recommends completing the serologic workup for common liver diseases 7
The Journal of the American College of Radiology suggests considering MRI with hepatocyte-specific contrast if better characterization of liver parenchyma or detection of small metastases is needed 4, 5
The American Gastroenterological Association advises arranging close clinical follow-up with serial liver chemistry testing 7
If elevations persist beyond 6 months or if there are signs of chronic liver disease or hepatic decompensation, the American Gastroenterological Association recommends proceeding to liver biopsy 7