Laboratory diagnosis of thalassemia

Abstract

Summary The thalassemias can be defined as α‐ or β‐thalassemias depending on the defective globin chain and on the underlying molecular defects. The recognition of carriers is possible by hematological tests. Both α‐ and β‐thalassemia carriers (heterozygotes) present with microcytic hypochromic parameters with or without mild anemia. Red cell indices and morphology followed by separation and measurement of Hb fractions are the basis for identification of carriers. In addition, iron status should be ascertained by ferritin or zinc protoporphyrin measurements and the iron/total iron‐binding capacity/saturation index. Mean corpuscular volume and mean corpuscular hemoglobin are markedly reduced (mean corpuscular volume: 60–70 fl; MCH: 19–23 pg) in β‐thalassemia carriers, whereas a slight to relevant reduction is usually observed in α‐carriers. HbA2 determination is the most decisive test for β‐carrier detection although it can be disturbed by the presence of δ‐thalassemia defects. In α‐thalassemia, HbA2 can be lower than normal and it assumes significant value when iron deficiency is excluded. Several algorithms have been introduced to discriminate from thalassemia carriers and subjects with iron‐deficient anemia; because the only discriminating parameter is the red cell counts, these formulas must be used consciously. Molecular analysis is not required to confirm the diagnosis of β‐carrier, but it is necessary to confirm the α‐thalassemia carrier status. The molecular diagnosis is essential to predict severe transfusion‐dependent and intermediate‐to‐mild non‐transfusion‐dependent cases. DNA analysis on chorionic villi is the approach for prenatal diagnosis and the methods are the same used for mutations detection, according to the laboratory facilities and expertise.

Validation of new indices for differentiation between iron deficiency anemia and beta thalessemia trait, a study in pregnant females

“…20 In their study, the Mentzer indices were able to correctly diagnose 94.7% and 92.9% of cases, respectively, and both are easy to calculate. 21 Similar results (Mentzer index: sensitivity, 90.9%; specificity, 80.3%) were found by Ghafouri et al 19 Their results overlapped those of our study. In the present study, YI evaluated the discriminating function of the red cell indices and their derived formulae.…”

“…20 Ntaios et al reported a Sn and Sp of 59.78% and 99% respectively with YI of +0.58. 21 Hence Mentzer index showed high validity in this study and these results are comparable to other studies.…”

β-thalassemia minor, carbohydrate malabsorption and histamine intolerance

“…There are poor data on the precise prevalence, overall burden, and trends of these diseases in Europe. Although β-thalassemia minor sometimes causes mild anaemia, carriers of disease are usually clinically asymptomatic [6]. …”

Challenges in Early Infant Diagnosis of Beta Thalassemias

“…Laboratory diagnosis of thalassemia, which consists of blood film examinations and hemoglobin electrophoresis, are the most common modalities in our country since DNA analysis for  or ß globin mutations is high cost and only available in the capital city. On the other hand, diagnosis of thalassemia becomes more complicated because of high prevalence of iron deficiency anemia in the country [1]. Health survey data in 2001 showed the prevalence of deficiency anemia in infants 0-6 months, infants 6-12 months, and children under five years old were 61.3%, 64.8%, and 48.1%, respectively.…”