Objectives To emphasise the limits of sensibility regarding haemoglobin electrophoresis in beta thalassemia diagnosis.

Methods We performed haemoglobin electrophoresis and alcalino-resistant haemoglobin evaluation during a 7-year period (2000–7) for 146 children based on the following inclusion criteria: a suggestive clinical examination, positive family history and haematological features of thalassaemia (low levels of haemoglobin and medium erythrocyte volume correlated with high values for red cell distribution width and erythrocytes number, corresponding to a value below 13 for the Mantzer index). Patients with nutritional anaemia (low blood level for iron) and small infants (up to 6 months of age) were excluded from the study.

Results The haemoglobin electrophoresis evaluation was normal in 59 cases (40.41%) and modified in 87 cases (59.58%). The haemoglobin electrophoresis anomalies were divided as follows: one case with fetal haemoglobin persistence; two major beta-thalassaemia patients; three patients with intermediate beta-thalassaemia; three patients with D type haemoglobin; one case of heterozygote beta-delta thalassaemia (minor thalassaemia phenotype) and 78 cases with minor thalassaemia (53.42%).

Conclusions The patients with normal values of haemoglobin electrophoresis and microcytic anaemia with no improvement after iron therapy could be considered as “minimal” or “silent” thalassaemia (they need further investigations, eg, high performance liquid chromatography).