FROM ERYTHROCYTE SEDIMENTATION-RATE TO PROFILES OF ACUTE-PHASE PROTEINS

The main biological sign of inflammation is an increase in erythrocyte sedimentation rate (ESR). However it can be falsely normal (polyglobulia, cryoglobulinemia, hemoglobinopathy) or spuriously high in the absence of inflammation (anemia, hypergammaglobulinemia). In cases of doubt, the acute phase reactants (APR) should be measured: C reactive protein (CRP), fibrinogen, haptoglobin, alpha1 acid glycoprotein. They have different kinetics of variation and various degrees of increase (some - the so called ''negative'' proteins - actually decrease). Several pitfalls can be avoided if it is remembered that the APR themselves can be modified by causes other than inflammation: low fibrinogen in intravascular coagulation, very low haptoglobin in hemolysis, raised orosomucoide in renal insufficiency and elevated transferrin in iron deficiency. Furthermore liver insufficiency or leakage through the kidney or gut lesions can lower them. In some patients, the observed levels of APR are thus the result of opposite trends. In complex cases, these pathological mechanisms are more apparent on profiles which express the concomitant blood levels of several APR in a normalized or comparative manner. In medical practice, ESR serves first and foremost to detect an inflammatory syndrome. CRP is prominent among the APR because its changes show a great sensitivity, are independent of those of ESR and have a time course fitting closely that of the inflammatory processes. Profiles yield detailed information but rarely provide major evidence in the quest of a diagnosis or the choice of a treatment. Because of their cost they are to be used only in difficult cases.