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the hematocrit bias: a very brief introduction

by Neoteryx | 2 min read

illustration of blood cells forming a tunnel like structure

For decades, Dried Blood Spot (DBS) cards have served as a useful alternative to painful venipuncutre, cold chain shipping and storage, and other hassles of wet blood collection. However, they have come with their own problems that have sandbagged their widespread adoption.

Chief among the drawbacks of DBS cards is the "hematocrit bias," also known as the "hematocrit effect."

Hematocrit is, in short, the volume percentage of red blood cells in a blood sample. Viscosity determines how well the blood spreads on the filter paper used in DBS. Blood hematocrit generally has an inverse relationship to the spread. Blood with a high hematocrit level results in a smaller dried blood sample, and a lower hematocrit level results in larger-size samples.

The hematocrit bias refers to effect of this relationship on the quality and reliability of data generated from such samples. An unevenly spread sample can easily lead to a disproportionate result. It can be difficult to extract the appropriate amount of the required analyte from the surface of the DBS card. Add to this the variations in paper quality, punching, and other factors, and you've got real problems.

In many cases, it made more sense to just take a larger wet sample, through old methods, to ensure enough blood to hit the "gold standard" for reliable results.

Now, however, there is a better way.

two images side by side, left side traditional DBS filter paper next to the modern Mitra blood microsampler

The Mitra® device, based on volumetric absorptive microsampling technology, was created in a quest to solve for the limitations of familiar DBS technology in general, and the hematocrit bias in particular. Simply put, microsampling using VAMS® technology takes the hematocrit bias out of the sampling equation.

With microsampling, a quantitative, volumetrically accurate sample can be easily collected anywhere, at any time, by almost anyone, yielding results comparable to those from wet blood. Microsampling doubles down on the benefits of DBS while overcoming its limitations.

It's no wonder that lab directors who never took DBS seriously before are now buzzing with enthusiasm to try this advance in dried blood sampling. If you're ready to embrace the advantages of capillary blood sampling without worrying about the hematocrit bias, we've can help you get started. Contact Neoteryx now to discover how small samples can deliver big data for you and your lab.

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Originally published Mar 22, 2018 6:54:00 AM, updated on November 11, 2021

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