Hemoglobin screening in prospective blood donors: a comparison of methods.

The microhematocrit (MHCT) (MHCT) of blood obtained by ear lobe puncture (ELP) was found to be higher than that obtained by fingerstick (FS). Using copper sulfate solution to estimate hemoglobin concentration of ELP blood will lead to accepting prospective blood donors that would be rejected by fingerstick obtained samples. Raising the specific gravity of the copper sulfate solution from 1.053 to 1.055 for females and from 1.055 to 1.057 for males eliminates the discordance for males but leads to rejection of females at a high rate (20 per cent). The use of FS/MHCT to recheck those failing the gravimetric test with higher specific gravity copper sulfate is suggested. The MHCT of venous samples obtained via the needle at the conclusion of phlebotomy will be lower than the MHCT of a capillary sample obtained during screening because of a combination of : 1) hemodilution due to assumption of the recumbent position and 2) hemodilution in response to phlebotomy.