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Probe for Procalcitonin (PCT) in Blood

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

This test measures a protein called procalcitonin, which is produced by cells in response to infections, particularly bacterial infections. It helps doctors assess whether an infection is bacterial or viral.

Quick summary

["Procalcitonin helps guide treatment decisions, especially for infections that may require antibiotics."]

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

Key facts at a glance

LOINC
74731-1
Short code
Deprecated GP bact Bld Pos Prb Mag-Imp
Synonyms
Deprecated GP bact Bld Pos Prb Mag-Imp
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-mag-capture
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order this test if you have symptoms of an infection, such as fever, chills, or signs of illness. It can also be used to monitor your condition if you’re already taking antibiotics for an infection.

What Does a Positive Result Mean?

A higher level of procalcitonin often suggests a bacterial infection. However, it can also rise slightly with viral infections or other inflammatory conditions, so results should be interpreted by your healthcare provider in the context of your overall health and symptoms.

How Is the Test Performed?

A small amount of blood is drawn from a vein, usually in your arm. The blood sample is then sent to a lab for testing.

What Are Common Causes of Elevated Levels?

Elevated procalcitonin levels are most commonly seen in bacterial infections (e.g., pneumonia, sepsis), but they can also appear in other conditions like severe viral infections, certain cancers, or inflammatory diseases.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

PCT Blood Probe

Frequently asked questions

Will this test show if I have a viral infection?
No, procalcitonin levels can rise with both bacterial and some viral infections, but they are more specific for bacterial infections. Your doctor will consider the test result alongside other symptoms and tests to make a diagnosis.
How soon will I get my results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time. Your doctor will discuss the results with you during your follow-up visit.
Can I eat or drink before this test?
You can eat and drink normally before this test, as it does not require fasting. However, always follow your doctor’s specific instructions for your blood draw.
  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