Journal of

A B S T R A C T
Background and Objectives
Accurate hemoglobin measurement is essential in blood donor screening and contributes to donor safety and, potentially, blood product quality. Capillary hemoglobin measurement is commonly used in donor screening because of its speed, ease of use, and low sample-volume requirements. However, evidence for agreement between capillary and reference venous hemoglobin measurements remains limited, particularly at higher hemoglobin concentrations. This study aimed to evaluate the agreement between capillary and venous hemoglobin measurements in male blood donors with hemoglobin concentrations of 18 g/dL or higher.
Materials and Methods
This multicenter cross-sectional study was conducted across 21 Iranian blood transfusion centers and included 550 male blood donors aged 17–70 years. An initial capillary hemoglobin measurement was, followed by a confirmatory venous measurement using automated hematology analyzers. Agreement between the two methods was assessed using Pearson’s correlation coefficient, intraclass correlation coefficient , and Bland–Altman analysis.
Results
Mean hemoglobin concentrations measured by the capillary and venous methods were 18.95±0.86 and 19.02±0.93 g/dL, respectively, with no statistically significant difference between the methods. Both the Pearson correlation coefficient and the Intraclass Correlation Coefficient were 0.50, indicating a moderate association and, according to the study’s intraclass correlation coefficient interpretation criteria, moderate agreement. The mean bias was −0.07 g/dL. Bland–Altman analysis did not indicate a significant overall  systematic bias ; however , the dispersion of differences between the two methods increased with rising hemoglobin levels, particularly at values above 20 g/dL.
Conclusions 
Within the studied range, capillary hemoglobin measurement showed a small mean difference compared to venous measurement, with no statistically significant overall systematic bias. Nevertheless, the greater variability in measurement differences in  hemoglobin concentration above 20 g/dL suggests that capillary results in this range should be interpreted with caution. In such cases, confirming the findings with a  venous blood sample using a reference method may help improve the  accuracy of clinical decision-making.