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Procalcitonin Blood Test

Last updated July 9, 2019

Approved by: Maulik P. Purohit MD MPH

The Procalcitonin Blood Test is a test that measures levels of procalcitonin circulating in blood.


What are the other Names for this Test? (Equivalent Terms)

  • PCT Blood Test

What is Procalcitonin Blood Test? (Background Information)

  • Procalcitonin (PCT) is a precursor to the hormone calcitonin. It is normally produced by the thyroid gland. However, 2-4 hours after a severe bacterial infection, immune cells also begin to produce PCT, which leads to increased blood PCT levels
  • The increase in PCT levels accompanies internal bacterial infection; not infection by other pathogens, such as viruses. Thus, PCT is useful in differentiating bacteria from other infectious agents
  • High levels of procalcitonin are also observed during thyroid cancer. However, the test is not a useful diagnostic tool, in this case
  • The Procalcitonin Blood Test measures levels of procalcitonin circulating in blood

What are the Clinical Indications for performing the Procalcitonin Blood Test?

The following are clinical indicators for performing Procalcitonin Blood Test:

  • Elevated heart rate (tachycardia)
  • Fever
  • Low blood pressure (hypotension)
  • Rapid breathing (hyperventilation)
  • Altered mental status
  • In order to monitor the course of a known bacterial infection

How is the Specimen Collected for Procalcitonin Blood Test?

Sample required: Blood

Process: Insertion of a needle into an arm vein.

Preparation required: None

What is the Significance of the Procalcitonin Blood Test Result?

Procalcitonin (PCT) levels are directly related to the severity of a bacterial infection, thus:

  • High PCT levels could indicate a serious infection
  • Low PCT levels could indicate a minor infection

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful Information:

  • Genetic defects in procalcitonin can make it susceptible to aggregating. These aggregates deposit as amyloid. Diseases, caused by amyloid deposition are called amyloidoses

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

References and Information Sources used for the Article:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: March 10, 2014
Last updated: July 9, 2019