Use of technicon H*1 technology in routine thalassaemia screening.

In a retrospective study of 36 cases of alpha-thalassaemia trait, 43 cases of beta-thalassaemia trait and 45 cases of iron deficiency, we have assessed the performance of the Technicon H*1 erythrogram, the hypochromia minus microcytosis (H-M) index, and the discriminant function (DF). The diagnostic accuracy of the erythrogram pattern was 83.3% for alpha-thalassaemia trait and 95.3% for beta-thalassaemia trait. The diagnostic accuracy for the H-M index was 19.4% for alpha-thalassaemia trait, 72.1% for beta-thalassaemia trait and 91.1% for iron deficiency. By comparison, the DF gave a diagnostic accuracy of 75.0% for alpha-thalassaemia trait, 81.4% for beta-thalassaemia trait and 88.9% for iron deficiency when using a locally derived value for the constant (k) = 19.2. Our study shows that the H*1 erythrogram pattern, the H-M index and the DF are useful predictive indicators in routine laboratory screening for thalassaemia.