The effects of over-anticoagulated blood on hematocrit values by the microcentrifuge method.

Objective: To determine equivalency of hematocrit results by three methods.

Design: A total of 101 whole blood samples in EDTA tubes were analyzed in this repeated measures study.

Setting: East Carolina University's clinical laboratory science program, Greenville NC.

Participants: The blood specimens were from adult patients at Nash General Hospital in Rocky Mount NC who had a CBC performed.

Main Outcome Measure: Hematocrit values from a whole blood sample with EDTA anticoagulant performed by a Sysmex XE-2100 and by microcentrifuge with two different types of capillary tubes (i.e., heparinized and non-heparinized) filled from the EDTA tubes.

Results: The hematocrit means of the total sample for the three methods were 36.2%, 35.4%, and 35.6% for the Sysmex XE-2100, non-heparinized capillary tubes, and heparinized capillary tubes, respectively. Pearson correlation coefficient (pairwise) analyses produced significant r-values at an alpha of .01 for all three method comparisons.

Conclusions: Based on statistically significant Pearson (pairwise) correlation coefficients, the hematocrit values by all three methods can be considered relatively equivalent. The differences between methods are quite small and would be clinically insignificant, thus likely not altering clinical decisions. Though this study was conducted under somewhat ideal conditions relative to the blood specimens selected, the results indicate that the additional dilution produced in a heparinized capillary tube when being filled from an EDTA-anticoagulated tube is not sufficient to produce clinically different microhematocrit results as compared to using the recommended non-heparinized capillary tube.