Reference range:
1. The plasma PCT mass concentration of healthy people is less than 0.05ng/ml.
2. The plasma PCT mass concentration of the elderly, patients with chronic diseases, and less than 10% of healthy people is higher than 0.05ng/ml, up to 0.1ng/ml, but generally not more than 0.3ng/ml.
3. The diagnostic cut-off value of PCT in patients with sepsis is more than 0.5ng/ml, and the mass concentration of PCT in patients with severe sepsis and septic shock fluctuates between 5-500ng/ml. A very small number of patients with severe infection have plasma PCT levels exceeding 1000ng/ml.
Clinical significance:
The plasma PCT content of healthy people is extremely low, but in addition to thyroid trauma or tumors, it is significantly elevated in the serum of patients with systemic inflammatory response syndrome (SIRS), sepsis, acute and chronic pneumonia, acute pancreatitis, active hepatitis, trauma, etc., especially for patients with SIRS/sepsis, PCT (compared with WBC, IL-6, TNF-2, CRP, soluble selectin, etc.) is a very sensitive and specific serological marker. However, it remains at a low level during viral infection and tumor trauma. PCT can increase in the early stage of severe bacterial infection (after 2-3 hours), so it has early diagnostic value.
PCT concentration does not increase or slightly increases in diseases such as local infection, viral infection, chronic non-specific inflammation, cancer fever, graft-host rejection or autoimmunity, but only increases significantly in severe systemic infection. This is This determines the high specificity of PCT, so it can also be used for the differential diagnosis of various clinical situations.
PCT concentration is positively correlated with the severity of inflammation, and decreases to normal levels as the inflammation is controlled and the condition is alleviated. Therefore, PCT can be used as a reliable indicator to judge the condition and prognosis and to observe the efficacy. PCT has extensive and important clinical application value; it also provides standards for mortality and hospitalization time of ICU patients.
1. Department of Hematology and Oncology For patients with immunosuppression and neutropenia caused by chemotherapy or bone marrow transplantation, PCT can help make a clear diagnosis of systemic infections caused by bacteria and fungi. Even in chemotherapy patients, PCT can reliably detect and assess whether there is sepsis infection.
2. Post-operative sepsis, infection and multiple organ failure are still the most common causes of death in intensive care units today. Plasma PCT concentration is usually within the normal range in minor and medium-sized surgeries. In major surgeries such as major abdominal surgery or chest surgery, the PCT concentration often increases within 1-2 days after surgery, usually 0.5-2.0 ng·ml, and occasionally exceeds 5 ng·ml. , this condition often drops to normal levels within a few days with a half-life rate of 24 hours. Therefore, high or sustained high levels of PCT caused by infection after surgery can be easily identified.
12-24 hours after compound trauma, PCT is moderately elevated and can reach 2.0 ng·ml. In severe lung or chest trauma, PCT can reach 5 ng·ml. If there are no infectious complications, it generally drops to the normal range at a half-life rate.
3. Medical intensive care PCT selectively responds to systemic bacterial infections, similar bacterial infections and protozoal infections, but has no response or only mild response to aseptic inflammation and viral infections.
4. Transplant surgery PCT is used to diagnose infections in organ transplant patients. Immunosuppressive therapy severely weakens the anti-infection ability of organ transplant patients. PCT can indicate the presence of systemic infection as early as 2 hours after infection occurs. In the early stage of infection, PCT is >0.1 ng·ml, with a sensitivity of 77℅ and a specificity of 100℅. Monthly monitoring of PCT concentration can reliably evaluate the efficacy of antimicrobial therapy.
PCT is used in organ rejection. One of the main tasks of monitoring after organ transplantation is to clearly distinguish infection from organ rejection. Because the release of PCT is not caused by stimulation of acute or chronic organ rejection, high concentrations of PCT are considered to indicate the presence of infection. If the PCT concentration exceeds 10 ng·ml, 98% of the chance is infection rather than organ rejection.
5. Neonatology: The age-dependent normal value of PCT in premature infants and newborns: PCT reaches its physiological peak of 21ng·ml at 24-30 hours after birth, but the average value is only 2ng·ml. From the third day after birth, the normal reference value of PCT is the same as that of adults.
PCT is a highly specific indicator of neonatal sepsis: in premature infants and neonatal sepsis infections, PCT can make an earlier and more specific diagnosis than traditional methods, and its sensitivity and specificity for neonatal diagnosis can reach 100℅.
6. Pediatric PCT has high sensitivity and specificity for the differential diagnosis of bacterial and viral infections, so PCT can provide valuable information for the treatment of patients with non-specific infection symptoms.
7. Surgical PCT concentration is not affected by existing diseases such as cancer, allergies or autoimmune diseases. PCT is significantly better than other inflammatory factors such as CRP and cytokines. It is an objective and easy-to-detect indicator and has its own unique characteristics. diagnostic advantages. PCT is closely related to the occurrence and process of severe bacterial and septic infections, and can accurately reflect whether the source of infection causing lesions (such as peritonitis) has been eradicated. PCT can be used for monitoring surgical trauma or combined trauma.
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