Whole-blood hemoglobin determinations: a comparison of methodologies

Area of Science:

• Clinical Chemistry
• Hematology

Background:

• Accurate hemoglobin (Hb) measurement is crucial for diagnosing anemia and monitoring treatment.
• Spectrophotometric methods for Hb determination can be affected by interfering substances like carboxyhemoglobin (HbCO) and sample turbidity.
• Variability in commercial standards and diluents impacts the reliability of manual Hb assays.

Purpose of the Study:

• To evaluate the accuracy of the Coulter Model S for total hemoglobin measurement in the presence of elevated carboxyhemoglobin (HbCO).
• To assess the quality and reliability of commercial diluents and standards used for spectrophotometric cyanmethemoglobin (HiCN) determinations.
• To identify optimal methods for manual hemoglobin measurement in clinical laboratories.

Main Methods:

• Comparison of hemoglobin measurements between the Coulter Model S and manual spectrophotometric methods.
• Testing of various commercial diluents and standards for cyanmethemoglobin (HiCN) assay performance.
• Evaluation of sample turbidity and carboxyhemoglobin (HbCO) interference on different assay methods.
• Assessment of the impact of centrifugation on diluent reliability.

Main Results:

• The Coulter Model S accurately quantifies total hemoglobin (Hb) content, unaffected by elevated carboxyhemoglobin (HbCO) levels.
• Commercial diluents exhibited variable quality, with many causing sample turbidity.
• Manual hemoglobin determinations were often higher than Coulter S measurements, potentially due to turbidity.
• The Van Kampen and Zijlstra reagent, enhanced by centrifugation, proved to be the most reliable diluent.

Conclusions:

• The Coulter Model S offers a reliable method for total hemoglobin determination, even with HbCO interference.
• Manual spectrophotometric Hb assays are susceptible to errors from diluent quality, turbidity, and HbCO.
• Narrow-band-pass spectrophotometers are not recommended for routine HiCN determinations due to sensitivity to turbidity and HbCO.