The routine measurement of platelet volume: a comparison of light-scattering and aperture-impedance technologies

Abstract

The effect of dipotassium ethylenediaminetetra-acetic acid (EDTA) on platelet count and mean volume (MPV) was evaluated using two routine measurement systems, a Coulter S Plus (Phase 1) (S+) and a Technicon H6000 (H6000). In normal subjects (n = 29) MPV increased by 17% during 39 h storage in EDTA when measured by the S+. In contrast MPV decreased by 22% when measured by the H6000. MPV differences of up to 40% were observed between the two systems. Concomitant platelet counts, in both systems, changed by less than 4%. A mathematical model of the variation of MPV with storage time was constructed, enabling experimental results to be extrapolated, with accuracy, to time zero (MPV0). The H6000 average MPV0 was significantly larger than the S+ average MPV0. Using the anticoagulant sodium citrate and prostaglandin E1 (NaCitrate-PGE1) there were no significant changes in MPV measured by the S+ during 7 h storage, although a linear decrease in platelet count was observed. A decrease in H6000 MPV was observed whether the blood was stored in EDTA or NaCitrate-PGE1. Methodology, anti-coagulation and storage time all influence MPV. Until these determinants are standardised the clinical value of MPV cannot be assessed.

Association of Mean Platelet Volume With Risk of Stroke Among 3134 Individuals With History of Cerebrovascular Disease

“…21 First, platelets swell in a time-dependent fashion after blood sampling in EDTA. 19 The intention of conducting assays 24 to 48 hours after blood collection (when platelet swelling will have ceased 19,20,25 ) was intended to minimize such errors. However, a relatively large proportion was assayed outside of the proposed time window.…”

“…Second, the MPV measurements were made with the use of a different machine in each of the collaborating countries over a period of approximately 2 years. The quality control program identified machine-dependent differences between the average levels of MPV in the participating countries, especially between New Zealand (where the machine used an optical mechanism, in which measured MPV appears to decrease with swelling) and other countries (where machines used an electric impedance mechanism of assay, in which measured MPV tends to increase with swelling 25 ). Country stratification or a country dummy variable was used in all analyses, although such adjustment is unlikely to have controlled completely for the differences between the machines.…”

A Retrospective Evaluation of Mean Platelet Volume as a Discriminating Factor in Thrombocytopenia of Hypoproductive and Hyperdestructive Aetiologies

“…The data on the size of the platelets have interested physicians since the last three decades. [1][2][3] The recent advancements in automated hematology analyzers have added new dimensions to the platelet indices (mean platelet volume, plateletcrit, platelet distribution width and platelet -large cell ratio). While the data on red blood size (mean corpuscular volume) is universally acknowledged and even applied, the diagnostic and prognostic utility of platelet size (mean platelet volume) in thrombocytopenia is still in its nascent stage of exploration.…”

Mean platelet volume: a quick, easy determinant of thrombotic risk?

“…Conversely when MPV is measured by an optical light scatter system derived from the modal platelet size, the MPV decreases over time, possibly as a result of the dilution of cytoplasmic contents leading to a decrease in light scatter [6]. An equation allowing for the correction of MPV over time from venepuncture has been published [7], but this is not widely used because of the unpredictability in the time taken to equilibrate in individual samples.…”