[Development of the fingertip blood dilution method for blood cell counting]

For simple examination of blood disorders such as anemia, the results of blood cell counting using a small volume of blood sampled from a finger were evaluated. Because the sampling volume varies, tyramine was added to the blood dilution buffer as an internal standard. When blood is added to a tyramine-containing buffer, tyramine is diluted according to the blood volume regardless of the hematocrit. The degree of blood dilution can be calculated from the difference in the tyramine concentration. The diluted blood was measured for blood cell count items using XE-2100. After cell counting, the diluted blood was centrifuged, and the concentration of the internal standard in the supernatant was measured using the automated biochemical analyzer JCA-BM2250. Correlation coefficients of 0.824-0.995 were obtained in the blood cell counts between fingertip and venous blood samples from 48 volunteers. However, as platelet aggregation was observed by fingertip blood sampling, the correlation coefficient for the platelet count was 0.450. This method is considered to be useful for screening of blood disorders. It may also be applicable to medical care in remote areas and during disasters.