CBNAAT Test Normal Range Explained
Know about how and what is done in the CBNAAT test, and how to interpret the test results. Learn the tips for faster recovery from TB.
Written by Dr. J T Hema Pratima
Reviewed by Dr. Rohinipriyanka Pondugula MBBS
Last updated on 8th Aug, 2025
Introduction
If you or a loved one has been advised to take a CBNAAT (Cartridge-Based Nucleic Acid Amplification Test), it is an advanced diagnostic tool. As it's new, you might have questions about what it means and what the normal range is. This article will help you understand the test, its purpose, and what the results indicate in simple terms.
What is a CBNAAT Test?
The CBNAAT test is a highly advanced diagnostic tool used primarily to detect tuberculosis (TB). It is a rapid, automated test that identifies the genetic material (DNA) of the Mycobacterium tuberculosis bacteria, which causes TB. Unlike traditional tests that take weeks to give results, CBNAAT provides accurate findings within 2 hours.
Consult a Specialist Pulmonologist for TB diagnosis
Why is CBNAAT Important?
There are several advantages of the CBNAAT test, including:
- Fast and Accurate: Detects TB quickly, even in cases where other tests may miss it.
- Detects Drug Resistance: Helps identify if the TB strain is resistant to common drugs like Rifampicin, a crucial antibiotic for TB treatment.
- Useful for All Patients: Works well for both pulmonary (lung) and extrapulmonary (outside the lungs) TB.
Understanding CBNAAT Test Results
The interpretation of CBNAAT results includes positive, negative and invalid includes:
1. Positive Result
- If the test detects TB bacteria DNA, it means the person has an active TB infection.
- If Rifampicin resistance is also detected, the doctor will prescribe a different treatment plan.
2. Negative Result
A negative result means no TB DNA was found in the sample. However, in some cases (especially in early or very mild infections), the test may not detect TB. If symptoms persist, further testing may be needed.
3. Invalid/Error Result
Sometimes, the test may show an error due to technical issues. In such cases, the test may need to be repeated.
Is There a "Normal Range" for CBNAAT?
Unlike blood tests that have numerical ranges (e.g., sugar or cholesterol levels), CBNAAT is a qualitative test, meaning it gives a "Detected" (Positive) or "Not Detected" (Negative) result. There is no numerical normal range—it simply confirms the presence or absence of TB bacteria.
Who Should Get a CBNAAT Test?
You may need this test when:
- You have a persistent cough (for more than 2 weeks)
- You experience fever, night sweats, or unexplained weight loss
- You have been in close contact with a TB patient
- You have HIV or a weakened immune system (as TB risk is higher)
- Other TB tests (like sputum smear) were inconclusive
How is the CBNAAT Test Done?
The brief steps for the CBNAAT test include:
- Sample Collection: A sputum (mucus from the lungs) sample is usually taken. For extrapulmonary TB, other samples (like fluid from lymph nodes or the spine) may be used.
- Testing Process: The sample is placed in a cartridge, which is then inserted into the CBNAAT machine.
- Results: Available in about 2 hours.
What If My Test Is Positive?
In case the test result is positive:
- Consult a doctor immediately to start treatment.
- TB is curable with the right antibiotics, usually taken for 6-9 months.
- Complete the full course of medication to prevent drug resistance.
Tips for Managing TB
If diagnosed with TB, follow these steps for a faster recovery:
- Take medicines on time – Skipping doses can make TB harder to treat.
- Eat a nutritious diet – Include proteins, vitamins, and minerals to boost immunity.
- Avoid smoking and alcohol – They weaken the lungs and the immune system.
- Cover your mouth while coughing – Prevent spreading TB to others.
- Get enough rest – Helps the body fight the infection better.
When to Consult a Doctor?
If you have:
- A prolonged cough (more than 2 weeks)
- Fever, fatigue, or weight loss without reason
- Been exposed to someone with TB
Early detection and treatment can cure TB completely and prevent complications.
Final Thoughts
The CBNAAT test is a game-changer in TB diagnosis, providing fast and accurate results.The test is also an easy and simple procedure. If your test is positive, timely treatment along with Tips for managing TB can help you recover fully.
Consult Specialist Pulmonologist for TB diagnosis
Consult Specialist Pulmonologist for TB diagnosis
Dr. Varun Rajpal
Pulmonology Respiratory Medicine Specialist
12 Years • MBBS, DNB Respiratory Medicine, EDARM, IDCCM,FCCS,FSM, Certificate course in Diabetes.
Noida
DR. VARUN RAJPAL Lungs And Respiratory Care clinic., Noida
Dr Chetan Kumar
Pulmonology Respiratory Medicine Specialist
27 Years • MBBS, MD TB & CHEST DISEASE
Delhi
Cronus Hospital, Delhi
Dr. Ashish Kumar
Pulmonology Respiratory Medicine Specialist
14 Years • Doctor of Medicine, D.T.C.D
Noida
Noida Asthma and chest clinic, Noida
Dr. Hyder
Pulmonology Respiratory Medicine Specialist
5 Years • MBBS, MD (PULMONOLOGY)
Guntur
Kalam chest and multi-speciality clinic, Guntur
Dr. Lokesh Kumar Garg
Pulmonology Respiratory Medicine Specialist
15 Years • MBBS,DTCD,PGDS
Faridabad
Arsh Hospital, Faridabad
Consult a Specialist Pulmonologist for TB diagnosis
Dr. Varun Rajpal
Pulmonology Respiratory Medicine Specialist
12 Years • MBBS, DNB Respiratory Medicine, EDARM, IDCCM,FCCS,FSM, Certificate course in Diabetes.
Noida
DR. VARUN RAJPAL Lungs And Respiratory Care clinic., Noida
Dr Chetan Kumar
Pulmonology Respiratory Medicine Specialist
27 Years • MBBS, MD TB & CHEST DISEASE
Delhi
Cronus Hospital, Delhi
Dr. Ashish Kumar
Pulmonology Respiratory Medicine Specialist
14 Years • Doctor of Medicine, D.T.C.D
Noida
Noida Asthma and chest clinic, Noida
Dr. Hyder
Pulmonology Respiratory Medicine Specialist
5 Years • MBBS, MD (PULMONOLOGY)
Guntur
Kalam chest and multi-speciality clinic, Guntur
Dr. Lokesh Kumar Garg
Pulmonology Respiratory Medicine Specialist
15 Years • MBBS,DTCD,PGDS
Faridabad
Arsh Hospital, Faridabad
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