I want to inquire about verification of target mean/ranges for hematology analytes. We run a control material 20 times and calculate statistics such as mean, standard deviation, and coefficient of variation.

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An alternative is to use a limit of ± 25 percent but confine the analysis to samples with a platelet count of 40 × 10³/µL (40 × 10⁹/L) or greater. This is the approach taken with CAP proficiency testing, which uses only samples with platelet counts of 50 × 10³/µL (50 × 10⁹/L) or greater and an acceptability limit of ± 25 percent, as established under CLIA.

Sandhaus LM, Osei ES, Agrawal NN, Dillman CA, Meyerson HJ. Platelet counting by the Coulter LH 750, Sysmex XE 2100, and Advia 120: a comparative analysis using the RBC/platelet ratio reference method. Am J Clin Pathol. 2002;118(2):235–241.

Tim Skelton, MD, PhD
Medical Director
Core Laboratory and Laboratory Informatics
Lahey Hospital and Medical Center
Burlington, Mass.
Member, CAP Hematology/Clinical Microscopy Committee