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One-Minute Point-of-Care Anemia Test Shows Promise in New Study
A simple point-of-care testing device for anemia could provide more rapid diagnosis of the common blood disorder and allow inexpensive at-home self-monitoring of persons with chronic forms of the disease, according to researchers at Emory University.
The disposable self-testing device analyzes a single droplet of blood using a chemical reagent that produces visible color changes corresponding to different levels of anemia. The basic test produces results in about 60 seconds and requires no electrical power. A companion smartphone application can automatically correlate the visual results to specific blood hemoglobin levels.
A paper describing the device and comparing its sensitivity with that of gold-standard anemia testing was published August 30 in the Journal of Clinical Investigation.
Using a two-piece prototype device, the test works this way: The patient sticks a finger with a lance similar to those used by diabetics to produce a droplet of blood. The device’s cap, a small vial, is then touched to the droplet, drawing in a precise amount of blood using capillary action. The cap containing the blood sample is then placed onto the body of the clear plastic test kit, which contains a chemical reagent. After the cap is closed, the device is briefly shaken to mix the blood and the reagent.
Blood hemoglobin then serves as a catalyst for a reduction-oxidation reaction, which takes place in the device. After about 45 seconds, the reaction is complete, and the patient sees a color ranging from green–blue to red, indicating the degree of anemia.
A label on the device helps the patient interpret the color, or the device can be photographed with a smartphone running an application that automatically correlates the color to a specific hemoglobin level.
To evaluate the sensitivity and specificity of the device, blood was obtained from 238 children and adults. Each sample was tested four times using the device, and the results were compared with reports provided by conventional hematology analyzers.
The results of the 1-minute test were consistent with those of the conventional analysis. The smartphone app produced the best results for measuring severe anemia.
“The test doesn’t require a skilled technician or a draw of venous blood, and you see the results immediately,” said senior author Dr. Wilbur Lam. “We think this is an empowering system, both for the general public and for our patients."
The device could be on pharmacy shelves sometime in 2016, Lam says.
Source: Emory University; September 11, 2014.