Red Cell Indices and Formulas Used in Differentiation of β-Thalassemia Trait from Iron Deficiency in Thai School Children

Abstract

Red cell indices and formulas have been established as simple, fast, and inexpensive means for discrimination between the β-thalassemia (β-thal) trait and iron deficiency. However, there were no reports of the diagnostic reliability of different red cell indices and formulas in discrimination of β-thal trait from iron deficiency in the Thai population. The aim of this study was to examine the diagnostic accuracy of five red cell indices [red blood cell (RBC) count, mean corpuscular volume (MCV), mean corpuscular hemoglobin (Hb) (MCH), mean corpuscular Hb concentration (MCHC), and red cell distribution width (RDW)] and eight formulas (Sirdah, Green & King, RDW Index, Menzler, England & Fraser, Ehsani, Srivastava, and Shine & Lal). Their sensitivity, specificity, positive and negative prognostic value and efficiency, were analyzed in 77 Thai school children, 21 with the β-thal trait and 56 with iron deficiency. The Sirdah and Srivastava formulas proved to be the most reliable indexes as they had 100.0% sensitivity and negative predictive value, the highest efficiency (97.4%), and the highest Youden's Index value (96.4%). Therefore, these formulas could be used in initial discrimination of the β-thal trait from iron deficiency in Thai school children.

Red Cell Indices and Formulas Used in Differentiation ofβ-Thalassemia Trait from Iron Deficiency in Thai Adults

“…In the present study, RBC counts of b-thal trait were significantly higher than those of iron deficiency (5.7 vs. 4.3 Â 10 12 /L, p50.001) and was consistent with the previous studies (9)(10)(11)23). The RDW of the former was significantly lower than those of the latter (14.9 vs. 16.2%, p50.001).…”

“…However, it had a low specificity (66.70%) in detection of iron deficiency. The previous study in Thai school children, aged 8-14 years, showed that the Sirdah and Srivastava formulas provided the highest reliabilities in initial differentiation of b-thal trait from iron deficiency (10). Contrary to the present study, it showed that RDW/RBC was a reliable formula for discrimination between b-thal trait and iron deficiency in adult Thai subjects.…”

“…The contrary results could not be attributed to differences in the b-thal mutation types as reported by the previous studies (12,18,19). Because both school children in our previous study (10) and adult subjects in the present study are Thai and the most (470.0%) b-thal mutations in the Thai population are b 0 -thal codon 17 (A4T), codons 41/42 (ÀTCTT), codons 71/72 (+A) and IVSI-nt1 (G4T) mutations (20,21). However, the molecular analysis for b-thal mutations was not performed in the present study.…”

“…The inter-population differences in effectiveness of red cell indices and formulas in discrimination of b-thal trait from iron deficiency might be due to the differences of molecular spectrum of the b-thal disorders in various countries, the degree of anemia in iron deficient subjects, sample size, and mean age of subjects. The previous study in Thai school children showed that the Sirdah and Srivastava formulas proved to be the most reliable indexes for discrimination between the b-thal trait and iron deficiency (10). Whether these formulas could be applied to adult Thai subjects are unclear.…”

“…Moreover, blood features of thalassemia and iron deficiency are similar. Thus, there are many studies reporting the diagnostic reliability of different red cell indices and formulas used in discrimination of b-thal trait from iron deficiency (8)(9)(10)(11)(12). However, the screening reliability of these indexes is controversial and differ from one country to another (8,9,12).…”