What should be done with an ESR (Erythrocyte Sedimentation Rate) result of 43 mm/hr from a heparinized sample?

ESR Testing: Heparinized vs. EDTA Samples

The technician should call the unit/floor and request a new EDTA sample to repeat the test, as ESR determinations should not be performed on heparinized samples.

Why Heparinized Samples Are Inappropriate for ESR Testing

Heparin significantly affects erythrocyte sedimentation rate (ESR) results, leading to falsely elevated values. Research has demonstrated that:

• Heparin increases red blood cell aggregation, which directly impacts ESR measurements 1
• Even at various concentrations (25-150 U/ml), heparin can increase ESR by approximately 75% compared to properly collected samples 1
• This effect occurs because heparin alters the normal aggregation properties of red blood cells, creating a measurement that does not accurately reflect the patient's true inflammatory status

Proper Sample Collection for ESR Testing

ESR testing requires specific sample collection conditions:

• EDTA (ethylenediaminetetraacetic acid) is the appropriate anticoagulant for ESR determination
• EDTA stabilizes the blood sample without affecting red blood cell aggregation properties in the way heparin does
• Using the wrong anticoagulant (heparin) invalidates the result regardless of quality control being in range

Action Algorithm for Laboratory Technicians

1. Identify the inappropriate sample type (heparinized tube)
2. Do not report the result in the Laboratory Information System despite QC being in range
3. Contact the unit/floor to request a new sample collected in an EDTA tube
4. Document the rejection of the original sample and reason
5. Process the new EDTA sample when received

Important Considerations

• Quality control being "in range" only confirms that the testing equipment is functioning properly with control materials, not that the patient sample is appropriate
• The value of 43 mm/hr may be significantly elevated from the patient's true ESR due to heparin's effect on red blood cell aggregation
• Reporting potentially inaccurate results could lead to inappropriate clinical decisions affecting patient care and outcomes
• Similar issues exist with other coagulation tests, where EDTA and citrate samples cannot be used interchangeably 2, 3

Common Pitfalls to Avoid

• Do not report results from improperly collected samples even if QC is acceptable
• Do not assume that an elevated result (43 mm/hr) is clinically significant when the sample type is inappropriate
• Do not attempt to "correct" or adjust results from heparinized samples
• Do not immediately notify the physician of abnormal results from an improperly collected specimen

The proper handling of this situation ensures accurate laboratory results that physicians can rely on for clinical decision-making, ultimately improving patient care and outcomes.