How to Calculate Erythrocyte Sedimentation Rate

ESR (Erythrocyte Sedimentation Rate) Calculator

Calculate Westergren ESR and Reference Range Estimates

Distance the erythrocytes fell in the tube.

Standard Westergren is 1 hour.

Male Female

Calculated ESR Rate:

— mm/hr

Expected Max (Miller Formula)

— mm/hr

Clinical Interpretation

—

How to Calculate Erythrocyte Sedimentation Rate

The Erythrocyte Sedimentation Rate (ESR) is a common hematology test used to detect non-specific inflammation in the body. It measures how quickly red blood cells (erythrocytes) sink to the bottom of a vertical tube of anticoagulated blood.

The Basic ESR Formula

In a clinical setting using the Westergren method, the formula is straightforward:

ESR (mm/hr) = Distance of Fall (mm) / Time (hours)

Calculating Expected Normal Ranges (Miller Formula)

Because ESR naturally increases with age, clinicians often use the Miller Formula to estimate the upper limit of normal for a specific patient:

• For Men: Age (years) / 2
• For Women: (Age (years) + 10) / 2

Example Calculation

If a 60-year-old female has a blood sample where the plasma-erythrocyte interface drops 30mm in 1 hour:

1. Measured ESR: 30 mm / 1 hr = 30 mm/hr.
2. Normal Limit: (60 + 10) / 2 = 35 mm/hr.
3. Interpretation: Since 30 is less than 35, this result is within the age-adjusted normal range.

Factors Affecting Results

ESR can be elevated by factors other than inflammation, including anemia, pregnancy, and kidney disease. Conversely, conditions like polycythemia or sickle cell anemia can cause abnormally low ESR readings. Always consult a healthcare professional for clinical diagnosis.