Evaluation of the Mentzer index in the screening of minor Thalassemia

About 7.5% of the population carrier ß -thalassemia geve in Sistan &Baluchestan province,
indicating a high prevalence in this region.
Several babies are born with severe thalassemia every year in this area,
Requiring a considerable financial maintenance cost. To evaluate and set a simple valid index
for mass screening of thalassemia, this cross- sectional analytical study was performed. Atotal of
2964 male students studying in final years of their secondary school located all over the province,
were subjected to the CBC test in 1376 (1997), using culture counter. Those with MCV<80FL were
selected for the study and they were subsequently examined for the presence of HbA2 in their blood.
The persons with HbA2 ≥ 3.5 were considered as having minor thalassemia and those with HbA< 3.4
considered to have iron deficiency.
The results showed 397 persons with MCV <80FL, consisted of 182 minor thalassemia and 178
cases of iron deficiency. The mentzer index (MCV/RBC) was tested in all individuals with
MCV<80, those with the ratio of ≤13 were suspected to have minor thalassemia. The mentzer index
and HbA2 were compared in this group. Thirty-seven low MCV cases disrupted their co-operation
and the study, therefore, was continued with 360 subjects. The data analysis revealed true positive
minor thalassemia in 164, false positive in 99, true negative in 79, and false negative in 36 cases.
The sensitivity and specificity of the test were 80% and 44%, respectively. The findings showed
that the measurment of the mentzer index can be used as a cost beneficial simple test for a primary
screening of minor thalassemia broadly in Sistan &Baluchestan province.