Interpret Your Hepatitis B Surface Antigen Results
Enter your HBsAg value below and get an instant, free AI interpretation — a plain-English explanation checked against WHO/IFCC reference ranges.
Medical Disclaimer
This AI-generated interpretation is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Results may vary based on individual health factors not captured here.
Always consult a qualified healthcare professional before making any health decisions. Read full disclaimer →
Hepatitis B Surface Antigen Normal Ranges
HBsAg (Hepatitis B Surface Antigen) is the first serological marker to appear after Hepatitis B virus (HBV) infection, detectable 1–10 weeks after exposure — before symptoms or liver enzyme abnormalities appear.
| Reference Range | Unit | Notes |
|---|---|---|
| Negative / Non-reactive | qualitative | Negative = uninfected; Positive = active infection |
Also reported in: S/CO ratio.
Why Doctors Order the Hepatitis B Surface Antigen Test
HBsAg distinguishes active Hepatitis B infection (acute or chronic) from past resolved infection or vaccination. If HBsAg persists beyond 6 months, the infection is classified as chronic.
How to Enter Your HBsAg Result
Hepatitis B Surface Antigen is usually reported as a qualitative result — for example negative or positive — so enter it exactly as it is printed on your lab report. Some laboratories also report a numeric value (S/CO ratio); if yours does, choose the matching unit.
What a Negative or Positive HBsAg Result Can Mean
Negative (non-reactive) result
- A negative HBsAg means no active Hepatitis B infection (does not distinguish between never infected, resolved infection, or successfully vaccinated)
Positive (reactive) result
- Acute Hepatitis B infection (recent exposure within 1–6 months)
- Chronic Hepatitis B infection (HBsAg positive >6 months)
- Vertical transmission from mother to newborn (most common route in endemic areas)
- Unprotected sexual contact with infected person
- Shared needles (IV drug use)
These are common associations, not a diagnosis. A single result is read alongside your symptoms, history and other tests — discuss it with your doctor.
What Can Change Your HBsAg Result
Before you read too much into a result, consider whether any of these applied:
- HBsAg can be transiently positive for 1–18 days after HBV vaccination (very low-level, vaccine-induced)
- Some immunocompromised patients may have false-negative HBsAg despite HBV infection (test HBV DNA if clinical suspicion is high)
- High-dose biotin supplementation can interfere with some biotin-streptavidin immunoassays
Preparing for the test: No fasting required. A reactive (positive) HBsAg result on initial testing should be confirmed with a repeat HBsAg test on the same sample using a neutralization assay or a second method, per standard laboratory protocols.
Symptoms That Often Prompt HBsAg Testing
- Many acute HBV infections are asymptomatic (subclinical), especially in children
- Symptomatic acute hepatitis: jaundice (yellowing of skin/eyes), dark urine, pale stools
- Fatigue, loss of appetite, nausea, vomiting, right upper abdominal pain
- Low-grade fever and joint pain (serum sickness-like prodrome)
- Chronic HBV: often asymptomatic for decades; fatigue is common
Want the full clinical guide to Hepatitis B Surface Antigen?
Reference ranges, causes, symptoms, preparation, and FAQs.