Erythrocyte Sedimentation Rate: Normal range and text explanation

 Erythrocyte Sedimentation Rate

Normal range (Westergren Method)

Male: up to 15 mm/hr

Female: up to 20 mm/hr

Child: up to 10 mm/hr

Newborn: 0-2 mm/hr

Indications

The ESR is a nonspecific test used to detect illnesses associated with acute and chronic infection, inflammation, advanced neoplasm, and tissue necrosis or infarction.

Test Explanation

ESR is a measurement of the rate at which the red blood cells (RBCs) settle in saline solution or plasma over a specified time period. It is nonspecific and therefore not diagnostic for any particular organ disease or injury. Because inflammatory, neoplastic, infectious, and necrotic diseases increase the protein (mainly fibrinogen) content of plasma, RBCs have a tendency to stack up on one another, increasing their weight and causing them to descend faster. Therefore in these diseases the ESR  will be increased. ESR provides same information as an acute--phase reactant protein. That is to say that it occurs as a reaction to acute illnesses as described above.

The test can be used to detect occult disease. Many physicians use the ESR test in this way for routine patient evaluation for vague symptoms. Other physicians regards this test as so nonspecific that it is useless as a routine study. The ESR test occasionally can be helpful in differentiating disease entities or complaints. For example in a patient with chest pain ESR will be increased with myocardial infarction (MI) but will be normal in a patient with musculoskeletal chest pain.

The ESR is a fairly reliable indicator of the course of disease and therefore can be used to monitor disease therapy, especially for inflammatory autoimmune disease. In general, as the disease worsens, the ESR increases; as the disease improves, the ESR decreases. If the results of the ESR are equivocal or inconsistent with clinical impressions, the C-reactive protein test is often performed.

ESR has several limitations

• As mentioned above, it is nonspecific.
• It is sometimes not elevated in the face of active disease.
• Many other factors may influence the results

ESR elevation may lag behind other indicators early in an infection. Likewise, in the convalescent stage of disease or infection, the ESR may remain elevated longer than other disease indicators. ESR cannot be used as an indicator of tumor burden when it is associated with neoplastic diseases, such as myeloma or breast cancer.

Interfering factors

• Artificially lower results can occur when the collected specimen is allowed to stand longer than 3 hours before the test.
• Pregnancy (second and third trimester) can cause elevated levels.
• Menstruation can cause elevated levels.
• Some anemias can falsely increase the ESR. There are correction nomograms available for variations in RBC count.
• Polycythemia is associated with decreased ESR.

Procedure

• Fasting: No
• Blood tube commonly used: Yellow
• In the laboratory, the blood is aspirated into a calibrated Sedimentation and allowed to settle, usually for 60 minutes. The remaining clear area (plasma) is measured as the sedimentation rate.

Test results and clinical significance

Increased levels

• Chronic renal failure
• Malignant disease
• Bacterial infection
• Inflammatory disease
• Necrotic disease
• Severe anemias

Falsely decreased levels

• Sickle cell Anemia
• Spherocytosis
• Hypofibrinogenemia
• Polycythemia

    Reference:  Mosby's Manual of Diagnostic and Laboratory Tests