Akutfasereaktant

Akutfasereaktant, or acute-phase reactant, refers to a group of plasma proteins whose concentrations change markedly in response to inflammation, infection, tissue injury, or surgery. They are mainly produced by the liver under the influence of pro-inflammatory cytokines, especially interleukin-6 (IL-6), interleukin-1 (IL-1), and tumor necrosis factor-alpha (TNF-α). The response comprises two main directions: positive acute-phase reactants, which increase in concentration, and negative acute-phase reactants, which decrease.

Positive acute-phase reactants include C-reactive protein (CRP), serum amyloid A (SAA), fibrinogen, haptoglobin, ferritin, ceruloplasmin, and hepcidin. Some components of the complement system may also rise. Negative acute-phase reactants include albumin, transferrin, and transthyretin (prealbumin), which fall during inflammation. The hepatic shift in protein synthesis reflects the magnitude and duration of the inflammatory stimulus and can influence iron metabolism, osmotic balance, and coagulation.

Clinically, acute-phase reactants are used as biomarkers to detect and monitor inflammation, infection, and tissue injury. CRP is the most widely used test; it rises rapidly, typically within hours, and declines as inflammation resolves. High-sensitivity CRP (hs-CRP) is employed in cardiovascular risk assessment. While APR patterns can aid differential diagnosis, they are non-specific and can be affected by factors such as liver function, steroids, malnutrition, and chronic disease.