A proposed reference haematocrit derived from multiple MCHC determinations via haemoglobin measurements

Area of Science:

• Clinical Chemistry
• Hematology

Background:

• Accurate reference haematocrit is crucial for quality control and automated analyser evaluation.
• Current methods are complex, time-consuming, and use difficult-to-obtain reagents, often focusing only on trapped plasma errors.
• Existing methods do not address errors from white-cell contamination, tube plugging defects, or red-cell dehydration.

Purpose of the Study:

• To develop a simple, rapid, and reliable reference haematocrit procedure.
• To provide an easily performed method for quality control and automated analyser evaluation.
• To address multiple sources of error in haematocrit measurement.

Main Methods:

• Utilized the principle that haematocrit equals haemoglobin/MCHC (mean corpuscular haemoglobin concentration).
• Performed MCHC determinations using haemoglobin analyses on small volumes (6 microliters) of packed red cells.
• Selected cells from the mid-portion of the packed red cell column to avoid white-cell contamination and red-cell dehydration.
• Validated the absence of trapped plasma through a secondary centrifugation cycle.

Main Results:

• Achieved high accuracy in MCHC determinations with a coefficient of variation (CV) less than 0.5%.
• The proposed method effectively eliminates interference from white-cell contamination and red-cell dehydration.
• Demonstrated the absence of trapped plasma in the selected cell fraction after short centrifugation times (4 min at 10,000 r.c.f.).

Conclusions:

• The proposed method offers a simple, rapid, and reliable reference haematocrit procedure.
• This technique addresses key limitations and errors of existing methods, improving accuracy.
• It is suitable for quality control, calibrator preparation, and automated analyser evaluation.