Osmotic error in erythrocyte volume determinations

Area of Science:

• Hematology
• Clinical Chemistry
• Biophysics

Background:

• Erythrocytes exhibit different volumes when suspended in native plasma versus Isoton solutions.
• Osmotic forces and plasma composition influence erythrocyte volume discrepancies.
• Standard laboratory procedures may not account for these in vitro volume changes.

Purpose of the Study:

• To investigate the discrepancy in erythrocyte volume between native plasma and Isoton.
• To evaluate the impact of this discrepancy on electronic particle counter measurements.
• To highlight the importance of considering this matrix effect in quality assurance.

Main Methods:

• Comparison of erythrocyte volumes in native plasma and Isoton.
• Utilizing electronic particle counters (e.g., Coulter) for measurements.
• Analysis of factors influencing volume discrepancies, including osmolality and incubation time.

Main Results:

• Erythrocytes suspended in Isoton show altered volumes compared to those in native plasma.
• The magnitude of the volume difference varies with plasma osmolality and cell suspension duration.
• Mean Corpuscular Volume (MCV) and hematocrit values from electronic counters may deviate from true in vivo values.

Conclusions:

• The osmotic environment significantly affects erythrocyte volume measurements in vitro.
• Electronic particle counter-derived MCV and hematocrit can be inaccurate due to this matrix effect.
• Laboratory quality assurance programs must incorporate this erythrocyte volume discrepancy for accurate results.