What is PCT?

Procalcitonin (PCT) is a 116-amino acid peptide with a molecular weight of approximately 14.5 kDa and is a member of the calcitonin (CT) family.PCT is a protein whose plasma levels are elevated in severe bacterial, fungal, and parasitic infections, as well as in sepsis and multiple organ failure. PCT is not elevated in autoimmune, allergic and viral infections. Localised limited bacterial infections, minor infections and chronic inflammation do not lead to its elevation. Bacterial endotoxin serves a crucial role in the induction process.                                          

PCT reflects the degree of activity of the systemic inflammatory response. Factors affecting the level of PCT include the size and type of the infected organ, the type of bacteria, the degree of inflammation and the status of the immune response. In addition, PCT is only measurable 1-4 d after major surgery in a small number of patients.

Clinical application of PCT

Serum PCT level in humans is strongly associated with the progression of bacterial sepsis and septic shock. Moreover, It has also been shown that PCT can be induced by a variety of other stimuli, including bacterial endotoxins, pro-inflammatory cytokines, and triggering events such as injury or cardiogenic shock. PCT has become a testing and prognosis indicator for sepsis in most cases, and is also used as a biomarker of related inflammation caused by infections. Continuous monitoring of PCT is of great clinical value for observing infection development and evaluating prognosis.

Serum PCT concentrations are less than 0.05 µg/L in healthy individuals; in the elderly, chronically ill, and less than 10% of healthy individuals, serum PCT concentrations are greater than 0.05 µg/L and can be as high as 0.1 µg/L, but generally do not exceed 0.3 µg/L.

Specific clinical applications of PCT are shown below:

① PCT can be used as an acute parameter for the differential diagnosis of bacterial and non-bacterial infections and inflammation.

② When there is clinical suspicion of unexplained infections and sepsis, timely PCT is recommended to help further clarify the diagnosis of bacterial infectious diseases.

③ In patients with suspected sepsis, empirical antimicrobial therapy should be initiated immediately. a diagnosis of sepsis is facilitated by a PCT ≥0.5 μg/L.

④ In ICU patients with severe infections who are receiving antimicrobials, antimicrobial discontinuation is recommended when the PCT falls to 0.5 μg/L or less than 80% of peak concentrations.

⑤ Monitoring the dynamics of PCT after surgery for early detection of postoperative bacterial infections.

⑥ PCT can be an effective tool to guide the diagnosis and treatment of LRTI and the rational use of antimicrobials.

Capillary Blood PCT is usually performed by using a blood needle to puncture a specific part of the finger or heel to collect capillary blood for testing, and has the advantages of less pain during puncture, less blood collection, and easy operation, and is recommended for use in paediatric outpatient and emergency clinics.

Factors affecting PCT

Although PCT has been proposed as a serum inflammatory marker for bacterial infections, there are cases where the absence of bacterial infections or bacterial foci lead to elevated values of PCT. So the main reasons for elevated PCT are listed as shown below:

Bacterial infections accompanied by a systemic inflammatory response

(Peritonitis, soft tissue infections viral infections;HIV，Hepatitis B)

Sepsis, MODS Autoimmune diseases and chronic inflammation

Systemic fungal infections Allergic reactions (types I to IV)

Parasitic infections (dysentery) Localised limited bacterial infections, ulcers, superficial microbial graft development

Bile duct-induced pancreatitis   Toxic pancreatitis

Some cases after major surgical operations  Minor or intermediate surgical operations

Summary

PCT is more sensitive and clinically useful than full-scale C-reactive protein (CRP) and various inflammatory response factors (bacterial endotoxin, TNF-alpha, IL-2) for the diagnosis and identification of systemic bacterial infections, and for the judgement of the efficacy of treatment and prognosis. And PCT can be used as a biomarker for diagnosing Sepsis and identifying severe bacterial infections.Therefore, PCT is valuable for the early differential diagnosis, severity and prognosis assessment of bacterial and viral infections, SIRS, and sepsis, as well as guiding the use of antibiotics in the clinic, and is the gold standard for the diagnosis of infectious disease.

The ReLIA PCT and Terminal blood PCT Immunoassay is CE-marked cleared. For more details on ReLIA PCT and Terminal blood PCT Immunoassay products and prices please contact us at  marketing@ReLIAchina.com

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