Professor (Dr.) Mohammed Sawkat Hassan
Joint Editor
North East Medical Journal
ESR (Sed rate) is a non-specific measure of inflammation. The ESR is governed by the balance between prosedimentation factors, mainly fibrinogen, and those factors resisting sedimentation, namely the negative charge of the erythrocytes (zeta potential). When an inflammatory process is present, the high proportion of fibrinogen in the blood causes red blood cells to stick to each other. The red cells form stacks called rouleaux, which settle faster. Rouleaux formation can also occur in association with some lymphoproliferative disorders in which one or more immunoglobulins are secreted in high amounts.
Aids to diagnosis: Diseases associated with elevated ESR (almost any sudden or significant inflammatory condition may be associated with an elevated ESR): i) autoimmune disorders, ii) infective endocarditis and other systemic or localized infection, iii) IBD, iv) myeloma/lymphoma, v) pregnancy, vi) anemia, vii) CKD, viii) TB. An elevated ESR cannot establish any diagnosis by itself. However, a normal ESR does reduce the likelihood of giant cell arthritis, polymyalgia rheumatic and SBE.
To rule in or rule out a condition associated with an elevated ESR, patient’s history, clinical sign symptoms, physical examination and other test results required to be taken into consideration. However, up to 10% of normal, healthy people have a mildly elevated ESR and it tends to increase with age. The basal ESR is slightly higher in females.
Disease severity: It is a component of the PCDAI (Pediatric Crohn’s Disease Activity Index).
Monitoring response to therapy: The clinical usefulness of ESR is limited to monitoring the response to therapy in certain diseases e.g., temporal arthritis, polymyalgia rheumatica and rheumatoid arthritis.
Note: Since C-reactive protein levels in the blood rise more quickly after the inflammatory or infective process begins, ESR is often replaced with C-reactive protein measurement. However: both tests for ESR and CRP were found to be independently associated with a diagnosis (in cases of liver diseases, CRP is less synthesized, while ESR may be decreased in polycythemia, sickle cell anemia and congestive heart failure) and the combination of both measurements may improve diagnostic sensitivity and specificity.