Erythrocyte sedimentation rate (ESR) is a rate at which red blood cells (RBC) sediments or settle down on its weight in a period of one hour. It is a common hematology test that measures how quickly RBCs settles at the bottom of a test tube. During physiological conditions, RBCs settle down slowly. A faster than normal rate of settling of RBC indicates some pathological conditions like infection, inflammation, malignancy etc.

The extra proteins in the blood produced by inflammation, make the RBCs settle faster. When this happens, the ESR elevates.

Other names for ESR are sed rate, sedimentation rate, westergren sedimentation rate, wintrobe sedimentation rate.

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AIM OF ESR TEST:

Test is usually conducted to detect the presence of inflammation caused by conditions like infections, tumors and autoimmune diseases. Also helps in diagnose of some specific conditions like temporal arteritis, systemic vasculitis, polymyalgia rheumatica etc.

There are some conditions which are non-inflammatory, but still they can raise ESR. These include anemia, renal failure, obesity, aging, and female sex.

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RESULTS:

ESR HIGH THAN NORMAL;

If ESR is high than normal, it may indicate some inflammatory conditions like;

  • Infection
  • Rheumatic fever
  • Rheumatoid arthritis
  • Vascular disease
  • Inflammatory bowel disease
  • Kidney disease
  • Heart disease
  • Certain cancers i.e lymphoma, multiple myeloma

ESR LOWER THAN NORMAL:

ESR lower than normal indicates blood disorders like;

  • Sickle cell anemia
  • Polycythemia
  • Abnormal Increase in WBC, leukocytosis
  • Hyperviscosity of blood

MODERATELY ELEVATED ESR:

A moderate ESR is seen in conditions like pregnancy, menstruation, or may be in anemia. Some medicines like oral contraceptives, cortisone, aspirin etc also affects ESR.

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When to need an ESR?

If someone has inflammatory symptoms like fever, headache, weight loss, loss of appetite, anemia, joints and shoulder pain, then ESR is strongly suggested.

PROCEDURE:

Blood sample is drawn from a vein. Then in laboratory the sample is transferred into a vertical test tube, in which RBCs slowly settles at the bottom. This settling leaves a clear yellowish fluid at the top, which is actually blood plasma.

The result is reported in millimeters of clear fluid, present at the top portion of tube after one hour. Or simply, the portion through which RBC is descended in one hour. The normal range is  0-22 mm/hr for males and 0-29mm/hr in females.

MECHANISM:

Normally RBCs settles down slowly in ESR tube, leaving portion of plasma very clearly. While in the presence of  increased level of particular proteins called ACUTE PHASE REACTANTS, RBCs settles at a faster rate. The level of acute phase reactants such as C-reactive proteins (CRP) and fibrinogen increases in the blood in response to inflammation. People whose RBCs settle faster will have elevated ESR

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