7. Erythrocyte Sedimentation Rate (ESR)

What does ESR stand for?

Erythrocyte Sedimentation Rate.

What is the definition of ESR?

The rate at which red blood cells in anticoagulated blood settled in a standardized tube over a specific period.

What is the core principle behind ESR measurement?

Based on Stoke’s law, which states that the velocity of falling particles is affected by plasma protein concentration and the formation of rouleaux.

What are the two main methods used for ESR testing?

Wintrobe and Westergren.

Which method is most commonly used in hospitals for ESR testing?

The Modified Westergren method.

What does a high ESR indicate?

It indicates inflammation and is used for disease monitoring.

How is ESR measured?

By measuring the distance that red blood cells fall in a vertical tube over a given time period.

In what units is ESR reported?

Millimeters per hour (mm/h).

What factors affect ESR?

RBC size and shape, plasma fibrinogen levels, globulin levels, mechanical and technical factors.

What effect do increased fibrinogen levels have on ESR?

They cause increased settling, resulting in a higher ESR.

What is rouleaux in relation to ESR?

Rouleaux refers to the stacking of red blood cells, which allows them to settle faster.

Which anticoagulant is recommended for ESR testing?

EDTA is the recommended anticoagulant.

What are common causes of decreased ESR?

Sickle cell anemia, polycythemia vera, severe anemia.

What is the procedure for the Westergren method?

Mix anticoagulated blood, draw it into the tube, wipe the bottom, set upright, and read after 1 hour.

What limitations are associated with ESR testing?

Includes mechanical factors, improper sample handling, and physiological conditions affecting results.

What is the normal ESR value for adult men?

0-15 mm/h.

What is the normal ESR value for adult women?

0-20 mm/h.

What are key differences between Wintrobe and Westergren methods?

Differences include tube type, anticoagulant used, blood mixing, and sensitivity.

Which method is considered the reference standard for ESR measurement?

Westergren method.

What physiological conditions lead to increased ESR?

Conditions include infections, inflammation, tissue injury, and various cancers.

What is an abnormal effect of sickle cells on ESR?

They cannot form rouleaux and may give a falsely low ESR.

What role does plasma viscosity play in ESR?

ESR is inversely proportional to plasma viscosity.

How does extreme leukocytosis affect ESR?

Very high white blood cell counts can lead to a decreased ESR.

What is hypofibrinogenemia?

A condition of low fibrinogen levels which can lead to decreased ESR.

What might cause falsely elevated ESR readings?

Cold agglutinins, improper anticoagulation, or a tilted tube.

What automated methods are used for ESR testing?

Methods using undiluted EDTA blood with algorithms and photometric rheology.

What is the length and diameter of the Westergren tube?

30 cm long, 2.5 mm in diameter.

Why is it important to keep the ESR rack level?

To prevent tilting which can cause errors in the result.

What is a common aspect of quality control in ESR testing?

Running commercially prepared controls before testing patient samples.

How do rouleaux affect ESR measurement?

Rouleaux formation increases the mass of red blood cells leading to faster settling.

What is the significance of observing a higher ESR in pregnant women?

It is considered a normal physiological response.

How can automated analyzers differ from traditional methods of ESR measurement?

They may measure red cell aggregation kinetics rather than waiting for gravity.

What types of errors can affect the accuracy of an ESR test?

Errors like vibration, temperature variations, and hemolysis can affect results.

What kinds of diseases can present with elevated ESR?

Rheumatic diseases, infections, malignancies, and autoimmune conditions.

What happens to ESR results if a sample is hemolyzed?

Hemolyzed samples are unacceptable for accurate ESR measurement.

What is the maximum time a tube can stand vertically for ESR measurement?

One hour.

What factors can lead to falsely decreased ESR readings?

Technical errors, abnormal plasma proteins, or low fibrinogen levels.

What is the relationship between RBC mass and ESR?

ESR is directly proportional to RBC mass.

What is the primary use of ESR in clinical practice?

As a nonspecific screening test to indicate inflammation.

What is the range of ESR for children?

Varies, generally lower than adults and dependent on age.

How does rheumatoid arthritis affect ESR?

It typically causes an increase in ESR due to inflammation.