GlycosyiatedHemoglobins : HematologicConsiderations Determine Which Assay for

This letter was referred for comment to Becton Dickinson and Co. For the four analytes for which Dr. Steindel found differences, they also found “clinically insignificant” differences. They comment farther: “We also extracted the contents of the tube with distilled water and determined calcium and LDH. The range of calcium extracted from the tube measured by atomic absorption [spectroscopy] was 0.4 to 0.5 mg/L, which is of negligible level to introduce any contamination. Levels of lactate dehydrogenase assayed with a centrifugal analyzer ranged from 1 to 2 U/L with the distilled water extract, similar to levels obtained by extracting the contents of a non-additive tube. Levels of potassium and chloride are too low to measure with the distilled water extract. Therefore, it is our opinion that the thrombin tube is suitable for stat blood collection for routine clinical chemistry procedures.”