- ESR is a qualitative test that measures how fast a patient's red cells fall within a column of blood in a specified time period (measured in mm/hr)
- The ESR is non-specific test that is not diagnostic of any particular disease. However, when elevated, it may indicate the presence of an underlying inflammatory, neoplastic, rheumatologic or infectious process
- When the ESR test is normal; this is reassuring than a significant acute inflammatory, infectious, rheumatologic or neoplastic process is not present
- Commonly used methods to measure the ESR are
- Westergren (or modified Westergren) method
- Wintrobe hematocrit method
Technical overview of ESR
- Normal erythrocytes settle slowly as they do not form rouleaux, nor do they stack or aggregate together. Instead they repel each other because of the negative charge on their cell surfaces.
- Plasma proteins, especially fibrinogen tend to adhere to the red cell membrane and neutralize the surface charges and make the cells more likely to aggregate forming stacks of rouleaux. The aggregated (stacked) cells have a higher ratio of mass to surface area than single cells and, therefore, will fall out from the plasma more readily, resulting in higher ESR.
- The sedimentation rate is proportional to the size or mass of the falling RBCs and is inversely proportional to plasma viscosity.
- ESR has high sensitivity but low specificity.
The clinical utility of the ESR test includes:
- The ESR test has high sensitivity but low specificity
- The ESR test is often used as a screening test to aid in diagnosis of occult or symptomatic disease such as:
- To discriminate iron deficiency anemia from anemia of chronic disease
- To monitor the disease progression in inflammatory or malignant disease
- To monitor the disease progression and theraupetic efficacy in conditions such as:
- If there is no immediate serious clinical concern related to an elevated ESR, a repeat of the test in a couple of months is often reasonable rather than initiation of a search for occult disease
- ESR is used as a "sickness index" in the elderly
- High ESR correlates with poor prognosis of various types of cancer
- ESR is an excellent predictor of early relapse in Hodgkin's (but not the sole criterion), especially if the value remains elevated after chemotherapy or fails to drop to a normal level within six months after therapy
- In patients with solid tumors, an ESR >100 mm per hour is suggestive of metastatic disease
- Low hematocrit (<10%) interferes with the test results (ESR will be higher than it should be)
Additional information
- Factors with no clinically significant effect or questionable effect on ESR, include:
- Obesity
- Body temperature
- Recent meal
- Drugs such as Aspirin, NSAIDs
- Related laboratory tests include:
- Antinuclear antibody
- Complete blood count
- C-reactive protein
- Fibrinogen
- Microorganism-specific serologies and related cultures
- Protein electrophoresis
- Rheumatoid factor
Conditions associated with elevated ESR values include:
- Infectious diseases [Any significant infection will elevate ESR]
- Collagen vascular/Rheumatologic diseases
- Malignant and neoplastic conditions
- Breast cancer
- Chronic lymphocytic leukemia
- Colorectal cancer
- Gastric carcinoma
- Hodgkins disease
- Lymphoma
- Multiple myeloma
- Prostate cancer
- Renal cell carcinoma
- Metastatic malignant tumors
- Advanced age
- Gastrointestinal diseases
- Myocardial infarction
- Pregnancy - third month to 3 wks postpartum
- Renal disorders
- Subacute bacterial endocarditis (SBE)
- Miscellaneous disorders
- Anemia - acute or chronic (macrocytosis)
- Heavy metal poisoning (acute)
- Hypothyroidism
- Kawasaki's disease
- Primary macroglobulinemia
- Infantile cortical hyperostosis
- Sarcoidosis
- Thyroiditis
- Waldenström's macroglobulinemia
- Trauma from surgery or burn injury
- Drugs
- Acetylsalicylic acid
- Anticonvulsants
- Cephalothin
- Cephapirin
- Clozapine
- Cyclosporine A
- Dextran
- Etretinate
- Fluvastatin
- Hydralazine
- Hydrazine derivatives
- Indomethacin
- Isotretinoin
- Lomefloxacin
- Methyldopa
- Methysergide
- Misoprostol
- Nitrofurantoin
- Ofloxacin
- Oral contraceptives
- Procainamide
- Propafenone
- Quinidine
- Sulfamethoxazole
- Zolpidem
Factors, which cause false positive levels of ESR, include:
- Hemoconcentration due to prolonged tourniquet constriction
- High room temperature during the test procedure
- Heparin interferes the Westergren and modified Westergren methods
- Bubbles in the Westergren tube or pipette
- Excess tilting of the measurement column from vertical
- The presence of fibrinogen, globulins, C-reactive protein, and high cholesterol
Conditions associated with decreased ESR values include:
- Extreme leukocytosis
- Polycythemia
- Red blood cell abnormalities:
- Acanthocytosis
- Anisocytosis
- Microcytosis (Iron deficiency anemia)
- Poikilocytosis
- Sickle cell disease
- Spherocytosis
- Protein abnormalities
- Bile Salts
- Low plasma proteins due to liver and kidney disease
- Elevated blood glucose
- High phospholipids
- Drugs
- Aurothiomalate
- Corticotropin
- Cortisone
- Cyclophosphamide
- Dexamethasone
- Gold
- Hydroxychloroquine
- Leflunomide
- Methotrexate
- Minocycline
- Penicillamine
- Prednisolone
- Prednisone
- Quinine
- Steroids (high dose)
- Sulfasalazine
- Tamoxifen
- Trimethoprim
Factors, which cause false negative levels of ESR, include:
- Allowing the blood sample to stand >6 hrs before the test
- Low room temperature during the test procedure
- Movement or vibration of the surface on which the test is being conducted
- Dilutional error
- Inadequate mixing
- Clotted sample
- Short ESR tube
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