A new study has suggested that health care professionals should be careful when using measurements from a single drop of finger-prick blood. To achieve consistent test results, it’s necessary to combine up to six or nine drops of blood. The study, believed to be the first of its kind, is the work of two bioengineers at Rice University. It shows that measurements from just one drop of blood are highly variable, an important discovery in an age where devices that just use one drop of blood to give test results are becoming more and more available.
The study came about through work that one of the bioengineers was involved with to help develop new, low-cost tests for anemia, platelet and white blood cell counts. While the most accurate way to test for these properties is to draw blood from a vein and then send it to a lab, there are settings where results are needed quicker, the professional isn’t trained to draw vein blood or there’s no lab, which would make a finger-prick test a more viable option.
For their study, the researchers tested six droplets of blood drawn in succession from each of their 11 donors. They also ran another test with a separate set of donors to check whether the minimum droplet size made a difference, and checked all the results against blood taken from donors’ veins. The results of the tests showed that hemoglobin content, platelet count and white blood cell count varied significantly from drop to drop. The results, according to the researchers, were at times surprising. For example, the hemoglobin concentration in some donors changed by more than two grams per deciliter with just two successive drops of blood. The researchers pointed out the importance in understanding how different protocols can affect the results of finger-prick tests, and how the results of the same test can vary from patient to patient. The authors of the study found that averaging the results of six to nine successive droplet tests produced results on par with vein blood tests. If you’d like to learn more, you can click here, or take a look at this video below: