Download Erythrocyte Sedimentation Rate (ESR)

ERYTHROCYTE SEDIMENTATION RATE (ESR)
An Educational Supplement prepared by ALQEP – May 2000
The ESR is a test widely utilized for the assessment of inflammation. Although relatively easy to perform, it is not easily
monitored using standard quality control materials and is not readily amenable to external quality assurance
measurements. A number of technical and physiologic variables affect results. A prolonged ESR is a non-specific finding
not readily linked to any one pathologic condition. The following paragraphs outline important technical and physiologic
variables affecting ESR measurement and indicate those conditions which have been shown to be effectively screened or
monitored by the ESR.
ESR is the measurement of the suspension stability of red blood cells (RBCS) in plasma under specified test conditions.
The descent of the plasma-red cell interface is plotted against time, forming a typical sigmoid curve with three distinct
phases. The initial portion of the curve, the lag phase, reflects red cells rouleaux formation. During the second,
decantation phase, the plasma-red cell interface falls more rapidly. During the final phase, the cell aggregates pile up on
the bottom of the tube. The two main determinants of ESR are degree of red cell aggregation and packed cell volume
(hematocrit). The ESR test result, read at 60 minutes will include varying contributions from the three phases.
Technical sources of error affecting the ESR include:
Specimen is too old (EDTA > 4 hours) results in crenation and sphering , decreasing the ESR
Improper filling of ESR tube – bubbles will cause a falsely increased ESR
Inaccurate timing – less than or greater than 1 hour
Inaccurate reading
Temperature – an increase in temperature, increases the ESR, a decrease in temperature decreases the ESR
ESR tube not vertical – results in an increased ESR
Vibration of ESR tubes – results in an increased ESR
Physiological and pathological factors increasing the ESR include:
Increased levels of plasma proteins in infection, inflammation and malignant conditions (including fibrinogen, IgM and
alpha2-macroglobulins) – affect RBC aggregation
Anemia – decreased numbers of RBCS
Autoagglutination – similar to rouleaux formation, clumps fall faster
Macrocytes – increased surface area (heavier), RBCS fall faster
Hemolysis – destruction of the RBCS (decreased number)
© Copyright 2004 College of Physicians and Surgeons of Alberta
ERYTHROCYTE SEDIMENTATION RATE (ESR)
Physiological and pathological factors decreasing the ESR include:
Protein abnormalities (e.g. hypofibrinogenemia, hypogammaglobulinemia)
Spherocytes or crenated RBCS – inhibit rouleaux formation
Microcytes – decreased surface area (lighter), RBCS fall slower
Clinical Management:
The ESR is indicated in the diagnosis and therapeutic monitoring of temporal arteritis and polymyalgia rheumatica. It may
be helpful in resolving conflicting clinical evidence in patients with rheumatoid arthritis and with the evaluation and
management of patients with specific autoimmune, inflammatory or infectious disorders (e.g. pelvic inflammatory
disease, bacterial endocarditis, septic arthritis and osteomyelitis). It is not meant to be used to screen asymptomatic
persons for disease.
References:
1.
Morrison, Dr. D.M. Capital Health Authority / Dynacare Kasper Medical Laboratories Laboratory Bulletin (Vol.
4 No. 8), July 1999.
2.
Sox HL, Liang, MH. The Erythrocyte Sedimentation Rate: Guidelines for Rational Use. Annals of Internal
Medicine 104: pp. 515-523, 1986.
3.
NCCLS Document, H2-A3, Methods for the Erythrocyte Sedimentation Rate (ESR) Test – Third Edition;
Approved Standard (Vol. 13, No. 8), August 1993.
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Alberta Laboratory Quality Enhancement Program
© Copyright 2004 College of Physicians and Surgeons of Alberta
CPSA: May 2000