Blood test results vary from drop to drop in fingerprick tests

http://www.eurekalert.org/pub_releases/2015-11/ru-btr111715.php

Public Release: 17-Nov-2015
Blood test results vary from drop to drop in fingerprick tests
Rice study: 6 to 9 drops of blood may be needed for consistent measurements
Rice University

When it comes to needles and drawing blood, most patients agree that bigger is not better. But in the first study of its kind, Rice University bioengineers have found results from a single drop of blood are highly variable, and as many as six to nine drops must be combined to achieve consistent results.

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Bond and Richards-Kortum found that hemoglobin content, platelet count and WBC count each varied significantly from drop to drop.

"Some of the differences were surprising," Bond said. "For example, in some donors, the hemoglobin concentration changed by more than two grams per deciliter in the span of two successive drops of blood."

Bond and Richards-Kortum found that averaging the results of the droplet tests could produce results that were on par with venous blood tests, but tests on six to nine drops blood were needed to achieve consistent results.

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