Infections & SerologyNo Fasting RequiredTurnaround: 4–8 hours (same day)

Hepatitis B Surface Antigen (HBsAg)

Also known as: HBsAg Test, Australia Antigen, Hep B Screen, HBsAg Rapid / ECLIA

Parameters Measured in the Report

A breakdown of individual biomarkers and biological reference intervals typically found in your report:

Biomarker	Standard Range	Unit	What It Means
HBsAg (Qualitative / Index) (HBsAg)	Non-Reactive / Negative (< 1.0 index COI)	Cutoff Index (COI)	Outer envelope protein of HBV; positive indicates active (acute or chronic) viral infection.

* Note: Reference ranges may vary slightly between testing instruments and reagent kits. Always refer to the reference interval printed on your specific pathology report.

Clinical Focus

Qualitative and quantitative detection of Hepatitis B virus outer surface envelope protein in blood.

Sample & Specimen

Venous blood (Serum tube)

Fasting Protocol

No fasting required. Maintain regular diet and fluid intake.

Turnaround Time

4–8 hours (same day)

What Is This Test?

The Hepatitis B Surface Antigen (HBsAg) test is the primary diagnostic screening tool for detecting active infection with the Hepatitis B Virus (HBV). Transmitted through blood, perinatal transmission from mother to baby, and sexual contact, HBV infects hepatocytes in the liver and can persist silently for decades. HBsAg is the very first immunological marker to appear in the bloodstream — detectable as early as 1 to 9 weeks post-exposure, well before clinical symptoms or liver enzyme elevations appear. Persistence of HBsAg in the blood for **longer than 6 months** defines Chronic Hepatitis B infection, carrying elevated risks for cirrhosis and hepatocellular carcinoma.

Why Did Your Doctor Order This Test?

Physicians routinely prescribe the Hepatitis B (HBsAg) in the following clinical scenarios:

Screening for viral hepatitis in patients with jaundice, dark urine, pale stools, elevated ALT/AST, or chronic fatigue

Mandatory routine prenatal screening in all pregnant women to enable immediate newborn immunoprophylaxis

Mandatory pre-operative infectious screening prior to all surgical procedures and dental interventions

Screening high-risk groups: healthcare workers, dialysis patients, household contacts of known carriers, and blood donors

How to Prepare Before Your Test

Fasting Requirement: No fasting required. Maintain regular diet and fluid intake.

No fasting or special preparation required.

Understanding Your Results

What higher or lower readings generally mean in clinical practice:

If Values Are Higher Than Normal

A Reactive / Positive HBsAg confirms active Hepatitis B infection and potential infectiousness. The patient requires complete viral workup: HBeAg/Anti-HBe, HBV DNA Viral Load by PCR, and Liver Function Tests to assess liver inflammation and guide antiviral therapy (e.g., tenofovir, entecavir).

If Values Are Lower Than Normal

A Non-Reactive / Negative HBsAg indicates the absence of detectable active viral antigen. (To verify immunity from past Hepatitis B vaccination, an **Anti-HBs antibody** test is performed; titers > 10 mIU/mL confirm protective immunity).

Frequently Asked Questions

What is the difference between HBsAg and Anti-HBs?

HBsAg is the virus protein itself (positive means active infection). Anti-HBs is the protective antibody your immune system creates after recovery or after successful vaccination (positive means you are immune and protected).

Related Laboratory Tests

Tests frequently prescribed together or used as follow-up investigations:

Liver Function Test (LFT / Hepatic Panel)

Bilirubin fractions, transaminases (ALT/SGPT, AST/SGOT), Alkaline Phosphatase (ALP), and proteins (Albumin, Globulin).

Complete Blood Count (CBC / Hemogram)

Counts and evaluates red blood cells, white blood cells, hemoglobin, hematocrit, and platelets.

PT / INR (Prothrombin Time & International Normalized Ratio)

Time in seconds for blood plasma to clot via the extrinsic pathway, and standardized international ratio.

Medical & Diagnostic Disclaimer

This guide is published for educational and patient informational purposes only. It is not a substitute for professional medical evaluation, diagnosis, or clinical advice.

A laboratory result that falls slightly outside standard statistical reference intervals does not automatically indicate disease; conversely, a normal result does not guarantee the absence of medical conditions. Only your attending physician can interpret lab findings in the context of your medical history, physical exam, and symptoms.