Hepatitis Testing for NASH Evaluation
Order hepatitis B surface antigen (HBsAg) and hepatitis C antibody with reflex HCV RNA testing to exclude viral hepatitis in patients being evaluated for NASH. 1, 2, 3
Essential Viral Hepatitis Screening
When evaluating a patient for NASH, the following hepatitis tests are mandatory to rule out viral causes of liver disease:
Core Required Tests:
- Hepatitis C antibody with reflex HCV RNA testing - This is the primary test to exclude hepatitis C, which can mimic NASH clinically 2, 3, 4
- Hepatitis B surface antigen (HBsAg) - Essential to rule out chronic hepatitis B infection 2, 3, 4
Additional Hepatitis B Tests to Consider:
- Hepatitis B surface antibody (HBsAb) - Useful for vaccine evaluation 3, 5
- Hepatitis B core antibody (HBcAb) IgG - Can identify occult HBV infection, though not everyone requires this test due to high positivity rates with uncertain clinical significance 3, 4, 5
- If HBsAg is positive: Check HBeAg, HBeAb, and quantitative HBV DNA, then refer to hepatology 5
Important Caveats:
Hepatitis E consideration: In patients with unexplained ALT elevations or acute-on-chronic liver injury, consider anti-HEV IgM or HEV RNA testing, as hepatitis E is now one of the most common causes of acute viral hepatitis and can cause fulminant disease in patients with pre-existing liver disease 6, 7
HIV screening: Should be performed if antiviral therapy may be needed, since tenofovir-based treatments are HIV-active medications 6
Complete Initial Workup Beyond Viral Hepatitis
The baseline evaluation should simultaneously assess for other causes of liver disease 1, 2, 3:
- Autoimmune markers: ANA, ASMA, AMA (though note that 21% of NAFLD patients have elevated ANA ≥1:160 or ASMA ≥1:40 without autoimmune hepatitis) 8
- Iron studies: Serum ferritin and transferrin saturation (elevated ferritin is common in NAFLD but doesn't require iron overload workup unless transferrin saturation is also elevated) 8, 3
- Alpha-1 antitrypsin (A1AT) 2, 3, 4
- Immunoglobulins - particularly if autoantibodies are positive 3
Clinical Context
The rationale for this testing strategy is straightforward: NASH is a diagnosis of exclusion. Viral hepatitis B and C can cause steatosis and inflammation that histologically and clinically overlap with NASH 8, 9. Most NASH clinical trials exclude patients with viral hepatitis to ensure a pure NASH population 8.
Critical pitfall: Do not assume elevated transaminases in an obese diabetic patient are automatically due to NASH without excluding viral hepatitis first. HCV in particular can coexist with metabolic risk factors and cause diagnostic confusion 9.
The 2021 Gastroenterology clinical care pathway 4 and 2022 AACE/AASLD guidelines 3 both explicitly list HBV and HCV serology as part of the initial evaluation table for suspected NAFLD, making this testing non-negotiable before confirming a NASH diagnosis.