Introduction

{“title”:”Hepatitis B Diagnosis and Antiviral Therapy in India: A Comprehensive Guide”,”excerpt”:”This article provides an exhaustive overview of laboratory investigations for diagnosing Hepatitis B in India, along with antiviral treatment regimens approved by the Indian regulatory authorities. It includes detailed testing protocols, drug choices, dosage schedules, monitoring guidelines, and special considerations for Indian patients.”,”content_html”:”n

Hepatitis B virus (HBV) infection remains a significant public health challenge in India, with an estimated prevalence of 4–5% among the general population. Early and accurate diagnosis followed by timely antiviral therapy is crucial to prevent cirrhosis, hepatocellular carcinoma, and liver failure. This article delineates the laboratory investigations required for definitive diagnosis in Indian clinical settings and outlines antiviral treatment plans endorsed by the Central Drugs Standard Control Organization (CDSCO) and the Indian Council of Medical Research (ICMR).

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1. Laboratory Investigations for Hepatitis B Diagnosis

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The diagnostic algorithm typically involves a combination of serological, molecular, and biochemical tests. The following sections detail each test, its clinical relevance, recommended cut‑offs, and interpretation guidelines specific to Indian laboratories.

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1.1 Initial Screening – Surface Antigen (HBsAg)

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• Method: Enzyme‑linked immunosorbent assay (ELISA) or chemiluminescent microparticle immunoassay (CMIA).

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• Reference Range: Negative if <1.0 IU/mL; Positive if ≥1.0 IU/mL.

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• Interpretation: A positive HBsAg indicates current HBV infection (acute or chronic). Repeat testing after 4–6 weeks is recommended to confirm persistence.

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1.2 Confirmation of Chronic Infection – HBeAg & Anti‑HBe

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• Method: ELISA for HBeAg; immunoassay for anti‑HBe.

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• Interpretation:n
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  • Positive HBeAg: High infectivity, active viral replication.

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  • Negative HBeAg but positive anti‑HBe: Lower infectivity, possible seroconversion.

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• Clinical Note: In India, 70–80% of chronic carriers are HBeAg‑negative but may still exhibit significant replication.

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1.3 Viral Load – Quantitative HBV DNA PCR

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• Method: Real‑time PCR using platforms such as Roche COBAS® AmpliPrep/COBAS® TaqMan or Bio-Rad Laboratories’ QIAGEN kits.

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• Detection Limit: <50 IU/mL; lower limits of detection are critical for treatment decisions.

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• Interpretation:n
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  • ≥20,000 IU/mL (or 2×10^4) in HBeAg‑positive patients and <2000 IU/mL (2×10^3) in HBeAg‑negative patients may indicate treatment eligibility.

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  • Patients with HBV DNA <2000 IU/mL and normal ALT are generally observed.

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1.4 Liver Function Tests (LFTs)

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• ALT, AST, ALP, GGT, Bilirubin (total & direct), Albumin, INR.

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• Interpretation: Elevated ALT/AST (≥2–3× upper limit) signifies active hepatic inflammation.

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1.5 Hepatitis B Core Antibody (Anti‑HBc IgM & IgG)

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• IgM: Indicates acute infection or reactivation.

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• IgG: Confirms past exposure; useful in serological pattern interpretation.

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1.6 Additional Serology – Anti‑HBs (Hepatitis B Surface Antibody)

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• Positive anti‑HBs (>10 mIU/mL) post‑vaccination or post‑treatment indicates immunity.

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1.7 Liver Imaging – Ultrasound & Fibroscan

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• Ultrasound: Detects focal lesions, biliary dilatation, cirrhosis.

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• Transient elastography (Fibroscan): Quantifies liver stiffness; >12.5 kPa suggests cirrhosis.

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1.8 Additional Tests – HBV Genotyping & Resistance Mutations

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• Indicated for patients on antiviral therapy or with virologic breakthrough.

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• Sequencing of the S, Pre‑S, or RT regions identifies genotypes (A–J) and resistance mutations (e.g., rtM204V/I).

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2. Antiviral Treatment Plans Approved in India

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The Indian regulatory framework recognizes the following nucleos(t)ide analogues for chronic HBV treatment: Entecavir, Tenofovir disoproxil fumarate (TDF), and tenofovir alafenamide (TAF). Lamivudine, adefovir dipivoxil, and telbivudine are no longer first‑line due to high resistance rates.

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2.1 First‑Line Agents

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• Entecavir (ETV)n
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  • Dose: 0.5 mg orally once daily for HBeAg‑positive; 1 mg daily for HBeAg‑negative.

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  • Resistance Profile: <0.1% after 3 years; lower than TDF in some studies.

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  • Renal Safety: Requires dose adjustment for eGFR <50 mL/min/1.73m².

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• Tenofovir disoproxil fumarate (TDF)n
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  • Dose: 300 mg orally once daily.

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  • Resistance: <1% after 5 years; excellent potency.

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  • Renal & Bone Safety: Monitor eGFR and serum phosphate; consider TAF if renal dysfunction.

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• Tenofovir alafenamide (TAF)n
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  • Dose: 25 mg orally once daily.

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  • Renal & Bone Safety: Superior profile compared to TDF; preferred in patients with pre‑existing renal or bone disease.

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2.2 Treatment Indications (Indian Guidelines 2024)

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• HBeAg‑positive with ALT >2× ULN and HBV DNA ≥20,000 IU/mL.

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• HBeAg‑negative with ALT >2× ULN and HBV DNA ≥2000 IU/mL.

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• Patients with cirrhosis irrespective of ALT/HBV DNA levels.

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• Pregnant women with high viral load (HBV DNA >10^7 IU/mL).

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2.3 Treatment Duration & Monitoring

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• HBeAg‑positive: Continue therapy until HBeAg seroconversion and sustained HBV DNA <2000 IU/mL for ≥12 months. Post‑seroconversion, continue for a minimum of 12–18 months.

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• HBeAg‑negative: Treat until HBV DNA <20 IU/mL for ≥2 years; then consider stopping with close monitoring.

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• Monitoring Schedule:n
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  • Every 3 months: ALT, AST, HBV DNA (quantitative), renal function.

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  • Every 6 months: eGFR, phosphate (for TDF/TAF), and bone density if risk factors.

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• Resistance Surveillance: If virologic breakthrough (≥1 log10 increase in HBV DNA), perform resistance testing and switch to a higher potency agent.

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2.4 Special Populations

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• Pediatrics: Entecavir 0.5 mg/kg/day (max 0.5 mg) or TDF 1 mg/kg/day (max 300 mg). Dose adjustment for renal impairment.

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• Pregnancy: TDF preferred over Entecavir due to limited data
  
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