Studies undertaken under controlled laboratory conditions using split venous samples have shown that the Hemocue has high correlation (0.96 with relative error of <3.5%) with Hb measured using the gold standard direct CMH method.18, 19, 20, 35 Studies report high specificity for the diagnosis of anemia in field methods using laboratory methods as the gold standard (94.2%)10, 22 but lower sensitivity ranging from 56% to 95%,30 implying that some individuals with anemia are not correctly diagnosed as such using Hemocue. This evidence concerns the gene GSTM1 and anemia (phenotype).