Procalcitonin (PCT) Lab Values

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Determine the significance and clinical use of measuring Procalcitonin in clinical practice


Lab Test Name:

 Procalcitonin- PCT



While procalcitonin is an amino acid that serves as a prohormone for calcitonin, its function is unrelated to calcitonin. Procalcitonin serves as an early indicator of systemic infection 



  • Amino acid
  • Prohormone to calcitonin
    • PCT function unrelated to calcitonin
  • Highly sensitive detector of infection
    • Bacterial vs. viral
    • Infection vs. systemic inflammation



  • Diagnosis & severity of sepsis
  • Pneumonia
  • Meningitis
  • Endocarditis
  • Late stage CKD
  • Acute exacerbation COPD
  • UTI with renal involvement in children
  • Evaluation of antibiotic therapy
  • Trauma, burns, surgery


Normal Therapeutic Values:

Normal – 

  • <0.05 ng/mL


  • Plasma separator preferred


What would cause increased levels?

Bacterial Etiology

  • Sepsis
  • Meningitis
  • Pneumonia
  • UTI


Conditions combined with infection where PCT would be elevated:

  • Recent major surgery
  • Severe trauma
  • Severe burns
  • Prolonged cardiogenic shock


What would cause decreased levels?

  • Effective treatment of infection
  • False lows – do not mean there is NO infection
    • Early course of localized infection
      • Empyema, osteomyelitis, endocarditis, etc.
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Hey everyone. Welcome to My name is Abby, and in this lesson, we’re going to discuss the normal values for procalcitonin. We’ll also discuss what conditions, disease processes, et cetera, that we might see in its increased or decreased value. Let’s dive in!


Procalcitonin, abbreviated PCT, is to be measured as an early indicator of a systemic infection. Now, what is procalcitonin? It’s an amino acid or a protein, and it’s a prohormone to calcitonin. And, while it’s a prohormone for calcitonin, its function is entirely unrelated, so it’s actually a highly sensitive detector of infection. It helps us differentiate between a bacterial infection versus a viral infection and when it’s an infection and not just systemic inflammation. Clinical indications are to diagnose and verify the severity of sepsis. This could also be taken in someone with pneumonia, meningitis, or endocarditis. It’s also going to be apparent in late-stage chronic kidney disease and, during an acute exacerbation of COPD. A UTI, uh, in children, when there’s a known renal involvement, will also cause us to draw a PCT lab. It also helps us to evaluate antibiotic therapy. Is the antibiotic working? Do we still have a high level of PCTs? And then, also, it will be taken in terms of trauma, burns, and surgery. Remember, mostly we’re looking at infection, not just inflammation. Now, this is streptococcus pneumonia, a causative bacteria of meningitis. That’s what increases our PCT values. 


Normal therapeutic values are quite low, less than 0.05 nanograms per milliliter. Collection of this specimen takes place in a plasma separator tube like this green top. When lab values are increased for PCT or procalcitonin, that means that there is a bacterial source causing the sepsis, the meningitis, the pneumonia, or the UTI, also in other states as well. Now, we talked a little bit, just barely, about COPD. It’s not always going to be increased in COPD, but it will when there’s that acute exacerbation. It’s very evident in lung tissue, it helps a lot with those types of disease processes. Now, conditions when an infection is apparent is like after a major surgery, PCT would be elevated if infection is present, with severe trauma, burns, and in the case of prolonged cardiogenic shock. The values for PCT will be decreased in the effective treatment of infection. The antibiotic has taken care of the infection in the body, lowering the PCT values. There could be false lows, and that doesn’t mean there is no infection, right? It could just be early-on in the course, something like empyema, osteomyelitis, endocarditis, and those types of infections may have kind of a late manifestation of an increase in PCT. 


Procalcitonin or PCT, is a lab value that is highly sensitive and specific to bacterial infection. I want you to think sepsis all day, when we think about PCT. That’s when we most often see it drawn. It’s going to be normal if the value is exceptionally low, like less than 0.05 nanograms per milliliter, increased in sepsis, and when there’s infection in severe trauma and burns. The value will be decreased when our antibiotic therapy is effective. 


Now you’ve all done great on this lesson. We know you can do it, and we love you. Now, go out and be your best self today, and as always happy nursing.


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