Determination of reference measurement values for the complete blood count
Gravimetrically controlled dilution of blood
The working group develops reference measurement procedures to determine blood cell concentrations. These are used in ring trials for the complete blood count to determine reference measurement values. This serves the external quality assurance of haematological laboratories as prescribed according to the Directive of the German Medical Association (RiliBÄK). For cell concentration measurement the blood sample is diluted with gravimetric control and then measured with a so called flow cytometer.
Flow cytometers count cells during passage of an orifice (electric measurement of a change in impedance) or passage through a laser beam (optical measurement of light scattering or fluorescence). The amount of sample is measured with a balance or using precision volumetric dosage systems developed by PTB. In this way the concentration of erythrocytes, leukocytes and platelets is determined. The approach can also be applied to measure the concentration of other blood cells.
The complete blood count also covers determination of the haemoglobin concentration. For this purpose all variants of haemoglobin are chemically transformed into a stable compound to determine the concentration at a proper dilution using a spectrophotometer.
Publications
Kammel, M.; Kummrow, A.; Neukammer, J.
Reference measurement procedures for the accurate determination of cell concentrations: present status and future developments
J. Lab. Med. 36 (2012) 25-34.
Reitz, S.; Kummrow, A.; Kammel, M.; Neukammer, J.
Determination of micro-litre volumes with high accuracy for flow cytometric blood cell counting
Meas. Sci. Technol. 21 (2010), 074006.
Witt K.; Wolf H.U.; Heuck C.; Kammel M.; Kummrow A.; Neukammer J.
Establishing traceability of photometric absorbance values for accurate measurements of the haemoglobin concentration in blood
Metrologia 50 (2013) 539-548.
Saraiva L.; Wang L.; Kammel M.; Kummrow A.; Atkinson E.; Lee J.Y.; Yalcinkaya B.; Akgöz M.; Höckner J.; Ruf A.; Engel A.; Zhang Y.Z.; O’Shea O.; Sassi M.P.; Divieto C.; Lekishvili T.; Campbell J.; Liu Y.; Wang J.; Stebbings R.; Gaigalas A.K.; Rigsby P.; Neukammer J.; Vessillier S.
Comparison of Volumetric and Bead-Based Counting of CD34 Cells by Single-Platform Flow Cytometry
Cytometry B 96B (2019) 508-513.
Measurands of the complete blood count
The parameters or derived quantities marked with * are referred to as erythrocyte indices and are calculated from the concentration of the red blood cells, the haemoglobin concentration and the haematocrit value. The symbols and formula symbols are based on DIN 58932-2.
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