Bing Yan, Department of Clinical Laboratory, Characteristic Medical Center (formerly 306 Hospital).
Edited by Liu Yan/Cui Yan, Medical Science Popularization Center
Many patients see the item procalcitonin (PCT) on the report list and think that it is related to the metabolism of calcium, but in fact, procalcitonin (PCT) is an important reference index for the diagnosis and treatment of bacterial infectious diseases, and compared with other inflammatory markers, procalcitonin (PCT) has better specificity for bacterial infection, and has been widely recognized in clinical application. Next, let's take a look at what is procalcitonin (PCT)? What are its advantages? How does it assist clinical diagnosis and treatment?
Biological properties of procalcitonin (PCT) (source)
Procalcitonin (PCT) is a glycoprotein with a molecular weight of 13 KDa, which is produced by parathyroid C cells under normal physiological conditions, so it is also known as thyroid calcitonin. However, in bacterial infection, macrophages and monocytes in the liver can also synthesize and secrete PCT, resulting in a significant increase in PCT levels.
In the case of inflammatory stimuli, especially bacterial infection/sepsis, various tissues and cell types of the body can produce PCT and release it into the blood circulatory system, showing rapid and highly specific growth (detectable in 3-6 hours).
Clinical application of procalcitonin (PCT) testing (use)
(1) Distinguish between non-bacterial infections and bacterial infections
When the body is invaded by bacteria and causes systemic inflammatory reactions, the serum PCT concentration will increase significantly. In the case of inflammatory reactions caused by viral infections, organ transplant rejection, autoimmune diseases, etc., the serum PCT concentration will remain low. The level of serum procalcitonin concentration can be used as an indicator to distinguish whether the infection is caused by bacteria.
In addition, the concentration of procalcitonin in the plasma of patients with systemic bacterial infection rises earlier than that of other inflammatory factors, usually rises sharply between 2 and 6 hours, and remains high for 8 to 24 hours. C-reactive protein (CRP) does not slowly increase until 8 to 12 hours later. Therefore, procalcitonin has better sensitivity and diagnostic specificity than other inflammatory markers.
(2) Important indicators for diagnosing and monitoring sepsis
Early diagnosis of sepsis is clinically important for the treatment of sepsis. There is evidence that procalcitonin is very effective in diagnosing sepsis, superior to CRP and white blood cell count (WBC), and the severity of sepsis can be judged by the level of procalcitonin markers.
As early as 2001, the International Sepsis Conference regarded PCT as one of the important indicators for the diagnosis of sepsis, and its specificity and sensitivity were as high as 100% in distinguishing systemic inflammatory response from severe sepsis.
(3) Assist in the diagnosis and treatment of heart failure complicated with lower respiratory tract infection
A prospective study of 1641 patients with dyspnea evaluated the diagnostic value of PCT in patients with dyspnea. The Kaplan-Meier curve showed that antibiotics in patients with acute heart failure with PCT > 0.21 ng/mL significantly reduced mortality (Figure B). Antibiotic use in patients with acute heart failure with a PCT < 0.05 ng/mL significantly increases mortality.
(4) Dynamic monitoring of PCT levels to guide the application of antibiotics
A series of problems such as drug resistance and the emergence of superbugs caused by the misuse of antibiotics have made people realize the importance of rational use of antibiotics. Based on the initial level of PCT in different clinical settings and the results of repeat measurements, it is clinically valuable to effectively guide the timing of initiation, continuation or discontinuation of antibiotics.
(5) Application of PCT in other diseases
Procalcitonin (PCT) is a very sensitive hematologic indicator of acute myocardial infarction and may be associated with the inflammatory process of acute myocardial infarction. In addition, procalcitonin can be used as an indicator of infection after surgery.
The economic value of procalcitonin (PCT) as an adjunct to guide antibiotic therapy
The economic value of PCT is mainly reflected in the reduction of the number of days of antibiotic treatment and the cost of antibiotics, the shortening of hospital stays, and the reduction of hospital costs, thereby improving the quality of life of patients and reducing medical costs.
(The picture comes from the Internet)