Which of the following can result in decreased ESR?

Which of the following can result in decreased ESR?

• A. Slightly tilted ESR tube
• B. High room temperature
• C. Use of heparin as anticoagulant
• D. Delayed testing of specimen

Answer: (D)

Erythrocyte sedimentation rate is highly sensitive to preanalytical factors that affect how red cells aggregate (rouleaux) and how viscous the plasma is. When testing is delayed, changes occur in the blood specimen over time that tend to reduce rouleaux formation and slow the settling of the cells, so the measured rate can be lower than it would be if you tested promptly. This is why delaying the test can yield a decreased ESR. In contrast, factors like tilting the tube can introduce measurement error and alter the path of sedimentation, higher room temperature tends to decrease plasma viscosity but often increases the rate of sedimentation rather than decrease it, and the type of anticoagulant (such as heparin) can affect results but is not the primary cause of a true, decreased ESR due to preanalytic handling. The key idea is that timely, properly handled samples best reflect the patient’s ESR.

Erythrocyte sedimentation rate is highly sensitive to preanalytical factors that affect how red cells aggregate (rouleaux) and how viscous the plasma is. When testing is delayed, changes occur in the blood specimen over time that tend to reduce rouleaux formation and slow the settling of the cells, so the measured rate can be lower than it would be if you tested promptly. This is why delaying the test can yield a decreased ESR.

In contrast, factors like tilting the tube can introduce measurement error and alter the path of sedimentation, higher room temperature tends to decrease plasma viscosity but often increases the rate of sedimentation rather than decrease it, and the type of anticoagulant (such as heparin) can affect results but is not the primary cause of a true, decreased ESR due to preanalytic handling. The key idea is that timely, properly handled samples best reflect the patient’s ESR.