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Lower Respiratory Tract Procalcitonin (PCT) Level in Nasopharyngeal Aspirate

Published: August 9, 2026Updated: August 16, 2026

This test measures procalcitonin, a protein produced by cells in the respiratory tract, to help assess whether a respiratory infection may be caused by bacteria rather than viruses. It’s used in the lower respiratory tract (e.g., from a nasal swab).

Quick summary

["Procalcitonin helps guide whether antibiotics may be needed for suspected bacterial lung infections."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
92986-9
Short code
C pneum DNA Lower resp Ql NAA+n-prb
Synonyms
C pneum DNA Lower resp Ql NAA+n-prb
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
non-probe-amp-tar
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order this test if you have symptoms like cough, fever, or breathing difficulties that suggest a possible bacterial infection in your lungs or airways. It helps distinguish between viral and bacterial causes, especially in cases like pneumonia or bronchitis.

How Is the Sample Collected?

A small sample of fluid from your nasal passage (nasopharyngeal aspirate) is collected using a soft tube. This is usually done by a healthcare provider in a clinic or hospital setting.

What Does the Test Result Mean?

Elevated levels of procalcitonin may indicate a bacterial infection, while lower or normal levels suggest a viral infection or no bacterial involvement. Your doctor will interpret results in the context of your symptoms and medical history.

Common Causes of Abnormal Results

High procalcitonin levels can occur with bacterial pneumonia, bronchitis, or other serious bacterial lung infections. Very low or absent levels are more typical of viral infections or non-infectious conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Nasal PCT Screening

Frequently asked questions

What are the normal results for this test?
Normal results vary by lab and test method, but generally, procalcitonin is low in viral infections and higher in bacterial infections. Your doctor will discuss the specific meaning of your result in relation to your health.
How soon will I get my results?
Results are typically available within 1–3 business days, depending on your lab and healthcare provider. Your doctor will contact you directly with the results.
Can I take anything before the test?
No special preparation is needed for this test. However, always follow your healthcare provider’s instructions if you have any concerns about fasting or medications.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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