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**Overview**: Quantiferon-TB Gold Panel**Introduction**: The Quantiferon-TB Gold Panel is a diagnostic tool designed to screen for tuberculosis using whole blood samples. In India, latent TB infection (LTBI) affects ~40 percent of the population (~400-500 million), with high progression risk in HIV, diabetes, or close contacts; IGRA (QFT-Gold) detects interferon-gamma release to TB antigens with higher specificity than TST in BCG-vaccinated populations. High morbidity from under-testing in rural/low-SES contacts or high-risk groups, limited IGRA labs, delayed isoniazid preventive therapy leading to active TB. Per TB practices aligned with NTEP and ICMR guidelines, the test employs immunoassay for TB Antigen 1, TB Antigen 2, and interferon-gamma release over 1-2 days with high accuracy, valuable for LTBI diagnosis in BCG-vaccinated adults. This diagnostic falls under TB screening and targets contacts, healthcare workers, or immunocompromised patients, addressing accurate detection to guide preventive therapy. With elevated morbidity due to under-screening, the test supports public health efforts by enabling precise LTBI identification and reducing active TB incidence. Its whole blood-based approach ensures reliable IGRA response.**Other Names**: QFT Gold Pnl.**FDA Status**: FDA approved, CLIA certified for hematology/immunology, compliant with 2025 standards.**Historical Milestone**: QFT-Gold standard since 2000s; in India, integrated in NTEP for high-risk groups.**Purpose**: The test assesses 3 parameters including TB Antigen 1 to guide TB screening, detect LTBI, inform preventive therapy.**Test Parameters**: 1. TB Antigen 1, 2. TB Antigen 2, 3. Interferon-Gamma Release.**Pretest Condition**: No fasting required; patients should have TB exposure risk.**Specimen**: 3 mL whole blood in specialized TB tubes, transported within specified times to maintain sample viability.**Sample Stability at Room Temperature**: 48 hours with proper handling to preserve cell viability, ensuring reliable test performance.**Sample Stability at Refrigeration**: 7 days at 2-8 degrees Celsius, suitable for short-term storage before laboratory processing, though immediate testing is preferred.**Sample Stability at Frozen**: Not applicable (fresh sample preferred for IGRA).**Medical History**: Patients should provide details on TB contact, BCG status.**Consent**: Written informed consent is required, detailing the test's purpose, potential risks of undetected LTBI including active TB, benefits of screening, and minimal discomfort from blood draw.**Procedural Considerations**: The test involves sample processing using immunoassay by trained personnel to ensure sterile technique and interpret IFN-gamma within 1-2 days using provided controls. Laboratories must maintain a controlled environment, adhere to quality assurance protocols.**Factors Affecting Result Accuracy**: Delays beyond stability periods, improper storage conditions, or immunosuppression can affect results. Correlation with clinical evaluation or additional testing is recommended to confirm findings.**Clinical Significance**: Positive IFN-gamma release indicates LTBI, necessitating specialist input.**Specialist Consultation**: Pulmonologists or TB specialists should be consulted for management.**Additional Supporting Tests**: Chest X-ray, TST for confirmation.**Test Limitations**: Does not distinguish active/LTBI; comprehensive approach required.**References**: Indian Journal of Tuberculosis 2024, TB Studies India 2023. |
