Complete Blood Count (CBC) Test
A molecular test to detect mutations in the pncA gene that cause resistance to pyrazinamide, an important antibiotic used to treat tuberculosis.
{"Detects genetic mutations that cause resistance to pyrazinamide antibiotic","Helps doctors choose the right antibiotics for tuberculosis treatment","Results guide personalized treatment plans for drug-resistant TB"}
Key facts at a glance
- LOINC
- 94059-3
- Short code
- PNCAMUT
- Synonyms
- Bacterial pncA drug res mut Islt/Spm
- Category
- chemistry
- Sample
- serum
- Container
- Sterile, leak-proof, screw-capped transport container (cryovial or 50 mL conical tube); can also be collected in serum separator tubes for serum-based testing or specialized mycobacterial transport media
- Units
- N/A
- Ref low
- 44
- Ref high
- 147
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- molgen
- CPT
- 87153
- SNOMED
- 122548000
- Specimen volume
- 2-5 mL of serum or 1-3 mL minimum specimen volume depending on testing methodology
- Stability
- Refrigerated at 2-8°C: up to 7 days; Frozen at -20°C or -70°C: up to 30 days for serum specimens. Avoid repeated freeze-thaw cycles. Transport on cold chain if shipping to reference laboratory.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–168 hours
- Order
- routine
What is a complete blood count (CBC) test, and exactly what does it measure in a sample of your blood?
This test looks for specific changes (mutations) in the pncA gene of bacteria, especially Mycobacterium tuberculosis (the germ that causes tuberculosis). These genetic changes can make the bacteria resistant to pyrazinamide, an important antibiotic used to treat tuberculosis.
Why might my healthcare provider order a complete blood count (CBC) test as part of my checkup or care?
If you have tuberculosis, this test helps your doctor know if the infection is resistant to pyrazinamide. This information is crucial for selecting the most effective combination of antibiotics for your treatment. Using the right medicines early can improve your chances of recovery and help prevent the spread of drug-resistant tuberculosis.
How is a complete blood count (CBC) test performed, and should I expect any pain during the blood draw?
A blood sample will be collected from you. In the laboratory, scientists will analyze the genetic material (DNA) from the bacteria to look for mutations in the pncA gene. This molecular testing method is fast and accurate.
What do the results of my complete blood count (CBC) test mean, and how will my doctor explain them to me?
If mutations are found (positive result), it means the tuberculosis bacteria are likely resistant to pyrazinamide. Your doctor will then choose different antibiotics. If no mutations are found (negative result), pyrazinamide may still be effective as part of your treatment plan.
Reference range
Adult: 44-147 U/LN/A
No fasting required. Patient should be informed about the purpose of the test. Specimen should be collected prior to initiation of anti-tuberculosis therapy when possible, or before next dose if already on therapy, to optimize detection of resistance mutations. Patient identity and specimen labeling must be verified before collection.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is important for combating drug-resistant tuberculosis. Detecting pncA gene mutations helps doctors personalize treatment, avoid ineffective antibiotics, and improve patient outcomes. It also helps prevent the spread of drug-resistant tuberculosis in the community.
Pyrazinamide is a key first-line antibiotic for tuberculosis treatment. Resistance to this drug, caused by pncA gene mutations, is a significant concern worldwide. This test provides critical information for effective disease management.
Frequently asked questions
Is the test painful?
How long does it take to get results?
What happens if I have drug-resistant TB?
Can I still spread TB to others if I have drug-resistant TB?
Sources
- 1CDC - Tuberculosis (TB)Source
- 2
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy