Because the levels of CRP rise much more significantly during acute inflammation than the levels of the other acute phase reactants, the CRP test has been used for decades to indicate the presence of systemic inflammation, infection, or sepsis.
Although its low specificity may be its primary drawback as a biomarker of sepsis in adults, it is commonly used to screen for early onset sepsis (occurring during the first 24 hours of life) because its sensitivity is generally considered to be very high in this setting .
Aiding diagnosis of sepsis with a CRP blood test
Because of the non-specific nature of the acute-phase response and the resulting rise in CRP levels, CRP cannot be used alone to diagnose any condition.
CRP can, however, provide supportive evidence for diagnosis of several infections, such as sepsis. For instance, when certain criteria are present, such as high fever and increased respiratory rate, CRP values can be used to diagnose an inflammatory condition or infection, which could develop into sepsis.
CRP in combination with a procalcitonin (PCT) test can effectively distinguish systemic inflammation from sepsis. Sepsis is the result of an uncontrolled immune-response to infection and has a mortality rate close to 30 %.
CRP, PCT and lactate or a combination of these biomarkers correlate with the severity of the infection and offer prognostic value around the clinical course of the patient.
If the lactate concentration exceeds 2.0 mmol/L, it is a sign of severe organ hypoperfusion, which may lead to septic shock with a mortality rate of around 50 % [2-6].
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