Hunt for the hidden trait

To assess the efficacy of a peripheral smear examination as a screening tool for β-thalassemia trait.

17 623 Leishman-stained peripheral smears were evaluated during the period from July 2006 to September 2007. The following parameters were studied: hemoglobin, red blood cell count, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration and red cell distribution width. All the cases that showed microcytosis, hypochromia, erythrocytosis and absence of anisopoikilocytosis were suspected of having the thalassemia trait (TT), and all these cases were further evaluated with Alkaline Hemoglobin Electrophoresis for confirmation.

Of the 17 623 smears examined, 60 cases were considered suspicious of having TT. Alkaline hemoglobin electrophoresis carried out on all these cases revealed an elevated HbA(2) (Mean = 7.5%). Five cases evaluated were found to have other hemoglobinopathies (1 Sickle cell trait, 3 Hb-E, 1 thalassemia intermedia).

Careful screening of peripheral smear is an invaluable screening tool for thalassemia trait (PPV - 95%). There must be awareness among the peripheral centers about the importance of peripheral smear screening and the affected persons should be counseled.