Inflammatory responses to tissue injury (the acute phase response) include alteration in serum protein concentration, especially increases in fibrinogen, serum amyloid A protein and C-reactive protein, and decrease in albumin. The changes occur in acute infection, during active phases of chronic inflammation and following injury. Erythrocyte sedimentation rate (ESR) is one of the methods which may indicate ongoing acute phase responses and may determine the severity and extent of the inflammation. ESR may also indicate some types of cancer. ESR may correlate with the disease activity. The principle of the test is that red cells are falling in plasma to the bottom in a straight, vertical positioned anticoagulated venous blood tube with a rate due to the difference in specific gravity between red cells and plasma. The result is the height of the clear plasma above upper limit of the column of sedimenting cells and expressed as ESR= X mm in 1 h. The sedimentation rate is influenced mainly by the extent to which the red cells form roulox, which sediment more rapidly than single cells. Other factors, which affect sedimentation include the ratio of red cells to plasma and some changes related with tube, and otherwise. The ESR is influenced by age, stage of the menstrual cycle and drugs. The ESR is higher in women than in men. It is especially low in polycytaemia, hypofibrino-genemia and congestive heart failure, and when there are abnormalities of the red cells such as poikilocytosis, spherocytosis or sickle cell. Although a normal ESR cannot be taken to exclude the presence of organic disease, the fact remains that the vast majority of acute or chronic infections and most neoplastic and degenerative diseases are associated with changes in the plasma proteins, which lead to an acceleration of sedimentation.

Acute phase response Erythrocyte sedimentation rate