Evaluation of the new red cell parameters on Beckman Coulter DxH800 automated haematology analyzer

Abstract

Objectives: The new red blood cell (RBC) parameters from automated haematology analyzers, such as reticulocyte haemoglobin content and percentage of hypochromic red cells or equivalent, are useful in the laboratory assessment of iron deficiency anaemia (IDA). However, the clinical utility of these parameters are confounded by thalassaemia trait (TT) especially in geographical areas of high thalassaemia prevalence. We aimed to evaluate the new formula derived from some red cell parameters on the Beckman Coulter DxH800 in distinguishing between IDA and TT in Hong Kong population.

Methods: A total of 246 normal subjects, 102 patients with IDA and 115 subjects with TT were accrued for the study. Concurrent chronic disorder and ovelapped IDA and TT cases were excluded. The new red cell parameters studied were red blood cell size factor (RSF), low haemoglobin density (LHD%), microcytic anaemia factor (MAF), standard deviation of conductivity of the non-reticulocyte population (SD-C-NRET) and unghosted cell (UGC). Comparison between groups was performed by student t-test and the diagnostic performance of the parameters was determined by receiver operating characteristic (ROC) curve analysis.

Results: Both LHD% and RSF were significantly higher in IDA than TT, whereas MAF was significantly lower. Although the biological basis was uncertain, SD-C-NRET was significantly lower in IDA than TT and showed the best diagnostic performance as a single parameter. A formula ((RBC+HB)*(HCT+SD-C-NRET))/(RDW-SD ) was devised to distinguish between IDA and TT. With a cutoff value of 23, the area under curve (AUC) was 0.995 (95% CI of 0.99 – 1.00), the sensitivity was 97% and the specificity was 99.1%. This formula was superior to other discriminant functions in the literature. The UGC number was not significantly different between alpha- and beta-TT.

Conclusions: The new RBC parameters on Beckman Coulter DxH800 provided useful information in distinguishing between IDA and TT, which is important for clinical decision making and streamlining further laboratory testing. This index can be used to screen patients who are likely to be IDA or TT for further hematological studies to confirm diagnosis.