Sunday, May 18, 2014

Erythrocyte Sedimentation Rate (ESR)

Erythrocyte Sedimentation Rate (ESR)


Background Information
Erythrocyte sedimentation rate (ESR), is a common hematology tests to determine/measure the rate at which RBCs sediment in a period of one hour. However it is a non-specific measure of inflammation and other confirmatory tests are required concurrently to diagnose clinical conditions of abnormal results.
The ESR is governed by the balance between pro-sedimentation 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 concentration of fibrinogen in the blood promotes the adherence and aggregation of RBCs together leading to a phenomenon called 'rouleaux,' (RBCs stacked up like a stack of coins). This rouleaux formation of RBCs will lead to an enhanced rate of sedimentation due to the increased density. 

Females tend to have a higher ESR, and menstruation and pregnancy can cause temporary elevations.
Visual presentation/explanation: 
Reference Ranges

Reportable range are usually  0 - 120 mm/hr, while sample with a result greater than 120 mm/hr should be reported as “>120 mm/hr". 

1. Adults (Westergren method):
  • Men under 50 years old: less than 15 mm/hr
  • Men over 50 years old: less than 20 mm/hr
  • Women under 50 years old: less than 20 mm/hr
  • Women over 50 years old: less than 30 mm/hr
2. Children (Westergren method):
  • Newborn: 0 to 2 mm/hr
  • Newborn to puberty: 3 to 13 mm/hr
Clinical Significance
An increased ESR rate may be due to:
  • Anemia
  • Cancers such as lymphoma or multiple myeloma
  • Kidney disease
  • Pregnancy
  • Thyroid disease
The immune system helps protect the body against harmful substances. In autoimmune disorder is a condition that occurs when the immune system mistakenly attacks and destroys healthy body tissue. ESR is often higher than normal in people with an autoimmune disorder. Common autoimmune disorders include:
  • Lupus
  • Rheumatoid arthritis in adults or children
Very high ESR levels occur with less common autoimmune disorders, including:
  • Allergic vasculitis
  • Giant cell arteritis
  • Hyperfibrinogenemia (increased fibrinogen levels in the blood)
  • Macroglobulinemia - primary
  • Necrotizing vasculitis
  • Polymyalgia rheumatica
An increased ESR rate may be due to some infections, including:
  • Body-wide (systemic) infection
  • Bone infections
  • Infection of the heart or heart valves
  • Rheumatic fever
  • Severe skin infections, such as erysipelas
  • Tuberculosis
Drugs that increase ESR
  • Dextran
  • Methyldopa
  • Oral contraceptives
  • Penicillamine procainamide
  • Theophylline
  • Vitamin A
Lower-than-normal levels occur with:
  • Congestive heart failure
  • Hyperviscosity
  • Hypofibrinogenemia (decreased fibrinogen levels)
  • Low plasma protein (due to liver or kidney disease)
  • Polycythemia
  • Sickle cell anemia
If the ESR is elevated, it is typically a result of globulins or fibrinogens. The doctor may then order a fibrinogen level (a clotting protein that is another marker of inflammation) and a serum protein electrophoresis to determine which of these (or both) is causing the elevated ESR.

Test Procedure (Modified WesterGren Method)
Whole blood collected are usually collected in EDTA tubes initially. The specimen is then transported at room temperature must be analyzed within 12hr of collection. Always check if sample is clotted or hemolyzed as they are criteria for test rejection.
Prior to performing tests, appropriate amount of EDTA-anti-coagulated whole blood is transferred into sodium citrated ESR 1.2ml Auto Plus Vacuum Tubes. Thoroughly mix the sample mixture by inverting a few times and introduce it to automated analyzers. Typical automated analysers use the modified Westergren method, which is a scientifically developed method to measure the traditional 60-min ESR procedure in only 30 minutes.


ESR vs C-Reactive Protein (CRP)
Both ESR and C-reactive protein (CRP) are markers of inflammation. CRP is an acute phase protein synthesized by the liver during an inflammatory reaction. CRP concentration in the blood is known to increase more rapidly on the onset of an inflammatory or infective process, while ESR on the other hand does not display substantive change. Since CRP is not affected by as many other factors as is ESR, this make CRP a better marker of inflammation. However, because ESR is an easily performed test, many doctors still use ESR as an initial test when they suspect an inflammatory condition in a patient. Several studies investigated the differential diagnostic values of ESR and CRP in inflammatory disease, and concluded ESR is a potential meaningful biomarker for disease differentiation

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