Type of test Blood
Normal findings
 Westergren method
 Male: ≤15 mm/hr  
Female: ≤ 20 mm/hr
Child: ≤ 10 mm/hr
Newborn: 0-2 mm/hr
Test explanation and related physiology
 ESR is a measurement of the rate with which the RBCs settle in saline or plasma over a specified time period. It is nonspecific and therefore not diagnostic for any particular organ dis ease or injury. Because acute and chronic infection, inflammation ( collagen-vascular diseases), advanced neoplasm, and tissue necrosis or infarction 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 is increased. ESR is considered an acute-phase or a reactant protein (i.e., it occurs as a reaction to acute illnesses).
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 regard 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.
The ESR is a fairly reliable indicator of the course of dis ease and can be used to monitor disease therapy, especially for inflammatory autoimmune diseases (e.g., temporal arteritis or polymyalgia rheumatica). 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.
 Interfering factors
 • Artificially low results can occur when the collected specimen is allowed to stand longer than 3 hours before the testing.
• Pregnancy (second and third trimesters) can cause elevations.
 • Menstruation can cause elevated levels.
• Polycythemia is associated with decreased ESR.
* Drugs that may cause increased ESR levels include dextran, methyldopa, oral contraceptives, penicillamine, procainamide, theophylline, and vitamin A.
* Drugs that may cause decreased levels include aspirin, cortisone, and quinine.
Procedure and patient care
• See inside front cover for Routine Blood Testing.
 • Fasting: no
 • Blood tube commonly used: lavender (verify with laboratory)
Abnormal findings
 Increased levels
- Chronic renal failure
- Malignant diseases
- Bacterial infection
- Inflammatory diseases
- Necrotic tissue diseases
- Hyperfibrinogenemia
- Macroglobulinemia
- Severe anemias (e.g., iron deficiency or B₁₂ deficiency)
Decreased levels
- Sickle cell anemia
- Spherocytosis
- Hypofibrinogenemia
- Polycythemia vera