Is it okay to do a HIDA (Hepatobiliary Iminodiacetic Acid) scan with hyperbilirubinemia?

HIDA Scan with Hyperbilirubinemia of 4.3 mg/dL

A HIDA scan can be safely performed with a bilirubin level of 4.3 mg/dL, as this level is below the 5 mg/dL threshold where diagnostic accuracy begins to decline significantly. While elevated bilirubin can affect interpretation, a level of 4.3 is within the acceptable range for reliable results.

Relationship Between Bilirubin Levels and HIDA Scan Accuracy

The diagnostic utility of HIDA scans varies based on bilirubin levels:

• Bilirubin <5 mg/dL: High sensitivity (100%) and specificity (100%) for detecting biliary complications 1
• Bilirubin >5 mg/dL: Maintained specificity (100%) but reduced sensitivity with increased false negatives and inconclusive results 1
• Bilirubin up to 5 mg/dL: Definitive diagnosis of hepatocellular disease and biliary obstruction is possible 2

Mechanism and Considerations

HIDA scans use technetium-99m labeled iminodiacetic acid compounds that are:

• Taken up by hepatocytes
• Excreted into the biliary system
• Visualized to assess biliary tract patency and function

Importantly, research has shown that even very high serum bilirubin levels do not necessarily impair hepatic uptake of the radiotracer. A case study demonstrated normal uptake and excretion of Tc-99m DISIDA despite serum indirect bilirubin exceeding 30 mg/dL 3.

Clinical Application Algorithm

1. For bilirubin levels <5 mg/dL (including 4.3 mg/dL):

   • Proceed with HIDA scan as planned
   • Expect reliable diagnostic results
   • Document bilirubin level for interpretation context

2. For bilirubin levels >5 mg/dL:

   • Consider alternative or additional imaging first (MRI with MRCP)
   • If HIDA scan is performed, interpret with caution
   • Be aware of increased risk of false negatives and inconclusive results

Diagnostic Pathway for Suspected Biliary Issues

1. Initial evaluation: Abdominal ultrasound (first-line imaging for suspected biliary obstruction) 4, 5
2. If ultrasound is negative but clinical suspicion persists:
   • HIDA scan (for bilirubin <5 mg/dL)
   • MRI with MRCP (especially for bilirubin >5 mg/dL) 5
3. For specific scenarios:
   • Suspected bile leak: HIDA scan is particularly useful 5
   • Suspected malignancy: CT abdomen with contrast 4

Important Caveats

• While a bilirubin of 4.3 mg/dL is acceptable for HIDA scanning, interpretation should account for this mild elevation
• Correlation with clinical status and other imaging modalities is essential to confirm detected abnormalities 6
• The American College of Radiology recommends MRI with MRCP for persistent clinical suspicion of liver disease despite negative ultrasound results 5

In summary, with a bilirubin level of 4.3 mg/dL, a HIDA scan can be performed with expectation of reliable diagnostic results, as this level falls below the 5 mg/dL threshold where diagnostic accuracy significantly diminishes.