Evaluation of hemoglobin of blood donors deferred by the copper sulphate method for hemoglobin estimation
Received 20 July 2006; received in revised form 21 November 2006; accepted 21 November 2006.
Abstract
Introduction
The copper sulphate (CuSO4) specific gravity test for Hb screening tends to give inappropriate failures. This prompted us to compare it with alternate screening methods.
Aim
To study the impact of inaccuracy of CuSO4 method on donor deferral.
Methods
Capillary and venous blood samples of 400 potential blood donors failing the primary Hb screening using appropriately standardized CuSO4 test (specific gravity 1.053) were tested by Hemocue photometer, the Hb colour scale, Cyanmethemoglobin method as well as the automated hematology analyser, which was considered as the standard reference method.
Results
One hundred and sixteen donors (29%) who failed the CuSO4 test had true Hb levels >12.5g/dl. The Hb levels of 131 (32.8%) deferred donors were between 12 and 12.5g/dl. The sensitivity of Hemocue, Hb colour scale and Cyanmethemoglobin was 99%, 97% and 96% and their specificity was 45%, 93% and 46%, respectively. The positive predictive values (PPV) of Hemocue and Cyanmethemoglobin methods were low (43% and 44%, respectively) but their negative predictive values (NPV) were high (99%, and 97%, respectively). The Hb colour scale had an overall best performance with a PPV of 96% and NPV of 95%.
Conclusion
The Hemoglobin colour scale which is inexpensive, convenient for field testing and has the overall best performance, is the most suitable for donor Hb screening. Since its readability is 12g/dl, lowering the donor Hb threshold to 12g/dl should be actively considered.
aAdvanced Centre for Treatment Research and Education in Cancer (ACTREC), Department of Transfusion Medicine, Tata Memorial Centre, Sector 22 Kharghar, Navi Mumbai 410208, India
ABSTRACT