Synonym/Acronym
Sed rate, ESR.
Rationale
To assist in diagnosing acute infection in diseases such as tissue necrosis, chronic infection, and acute inflammation.
Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction.
Normal Findings
Method: Westergren or modified Westergren.
| Age | Male | Female |
|---|
| Newborn | 0–2 mm/hr | 0–2 mm/hr | | Less than 50 yr | 0–15 mm/hr | 0–25 mm/hr | | 50 yr and older | 0–20 mm/hr | 0–30 mm/hr |
|
Study type: Blood collected in a completely filled lavender-top [EDTA] tube for the modified Westergren method or a completely filled gray-top [3.8% sodium citrate] tube for the original Westergren method; related body system: Circulatory/Hematopoietic and Immune systems.
The ESR is a measure of the rate of sedimentation of red blood cells (RBCs) in an anticoagulated whole blood sample over a specified period of time. The basis of the ESR test is the alteration of blood proteins by inflammatory and necrotic processes that cause the RBCs to stick together, become heavier, and rapidly settle at the bottom of a vertically held, calibrated tube over time. The most common promoter of rouleaux is an increase in circulating fibrinogen or globulin levels. In general, relatively little settling occurs in normal blood because normal RBCs do not form rouleaux and would not stack together.
The sedimentation rate is proportional to the size or mass of the falling RBCs and is inversely proportional to plasma viscosity. The test is a nonspecific indicator of disease and is an indicator of widespread inflammatory reaction due to infection or autoimmune disorders. Prolonged elevations are also present in malignant disease. The most commonly used method to measure the ESR is the Westergren (or modified Westergren) method.
The ESR is used less frequently as a primary study to identify and monitor inflammatory conditions. However, it remains an adjunctive tool in the workup of specific conditions such as temporal arthritis and rheumatoid arthritis. C-reactive protein has been shown to be a more sensitive and specific indicator of acute inflammation.
Factors That May Alter the Results of the Study
- Some drugs and other substances cause a systemic lupus erythematosus (SLE)-like syndrome that results in a physiological increase in ESR. These include anticonvulsants, nitrofurantoin, procainamide, and quinidine. Other drugs and substances that may cause an increased ESR include acetylsalicylic acid, antimicrobials (cephalothin, cyclosporin A), dextran, and oral contraceptives.
- Drugs and other substances that may cause a decrease in ESR include corticosteroids (corticotropin, cortisone, dexamethasone, prednisolone, prednisone), methotrexate, minocycline, NSAIDs, penicillamine, quinine, sulfasalazine, tamoxifen, and trimethoprim.
- Menstruation may cause falsely increased test results.
- Prolonged tourniquet constriction around the arm may cause hemoconcentration and falsely low values.
- The Westergren and modified Westergren methods are affected by heparin, which causes a false elevation in values.
- Bubbles in the Westergren tube or pipette, or tilting the measurement column more than 3 degrees from vertical, will falsely increase the values.
Other Considerations
- Movement or vibration of the surface on which the test is being conducted will affect the results.
- Inaccurate timing or a delay in performing the test once the specimen has been collected will invalidate test results.
- Specimens that are clotted, hemolyzed, or insufficient in volume should be rejected for analysis.
- The test should be performed within 4 hr of collection when the specimen has been stored at room temperature; delays in testing may result in decreased values. If a delay in testing is anticipated, refrigerate the sample at 2°C to 4°C; stability at refrigerated temperature is reported to be extended up to 12 hr. Refrigerated specimens should be brought to room temperature before testing.
Increased In
Increased rouleaux formation is associated with increased levels of fibrinogen and/or production of cytokines and other acute-phase reactant proteins in response to inflammation. Anemia of chronic disease as well as acute anemia influence the ESR because the decreased number of RBCs falls faster with the relatively increased plasma volume.
Decreased In
- Conditions resulting in high hemoglobin and RBC count
Before the Study: Planning and Implementation
Teaching the Patient What to Expect
- Discuss how this test can assist in identification of inflammation.
- Explain that a blood sample is needed for the test.
After the Study: Implementation & Evaluation Potential Nursing Actions
Treatment Considerations
- Teach how to perform hand hygiene to decrease infection risk.
- Discuss reportable symptoms of infection: fever, fatigue, malaise, chills, confusion, agitation, tachycardia.
- Discuss reportable symptoms of inflammation: red, swollen painful achy joints that are warm to the touch; joint stiffness; generalized fatigue and achiness; fever; chills.
- Teach the patient how to take and accurately record a temperature.
- Explain the importance of follow-up ESR to monitor the effectiveness of therapeutic interventions.
Clinical Judgement
- Consider an approach to clearly explain how trending lab results can assist in designing treatment modalities.
Follow-Up and Desired Outcomes
- Acknowledges contact information provided for the American College of Rheumatology (www.rheumatology.org) or the Arthritis Foundation (www.arthritis.org).
- Correctly describes reportable signs and symptoms of infection and inflammation.