ACUTE PHASE REACTANTS
Acute phase reactants are a group
of plasma proteins, the levels of which alter in response to tissue injury, inflammation
Interpretation: ESR provides a non-specific screening test for the presence of
an acute phase reaction. CRP measures one specific acute phase reactant. Although
the ESR and CRP may be valuable indicators of an acute phase response, normal results
do not exclude active disease. There is no added diagnostic value in measuring other
specific proteins. However, an awareness that they are acute phase reactants is of
value in the interpretation of results in patients with inflammatory or neoplastic
disorders. Levels of fibrinogen, ferritin, haptoglobins, a1-antitrypsin,
ceruloplasmin, factor VIII, von Willebrand factor, complement (CH50, CH100) and complement
components (C3 and C4) may be increased in an acute phase response; these increases
may mask a true deficiency state, if present. Levels of some proteins may be reduced
during an acute phase response, eg albumin, prealbumin, transferrin. Although
an acute phase response can be detected by serum protein electrophoresis, this is
not an appropriate test in this situation. Cryofibrinogen may also be present in
patients with an acute phase reaction, but this finding has no diagnostic value.
ERYTHROCYTE SEDIMENTATION RATE
C -REACTIVE PROTEIN
Reference: Pepys M. In: Roitt I et al eds. Encyclopedia of Immunology.
Academic Press 1992.