Thalassemia Screening among Royal Thai Army Medical Cadets

Military Medicine, Apr 2004 by Nathalang, Oytip, Arnutti, Pasra, Nillakupt, Kamolthip

In Hb E trait subjects, the mean values of Hb and Hct were 14.5 � 0.9 g/dL and 43.4 � 3%, respectively. The mean values of MCV, MCH, and MCHC were 78.9 � 3.5 fl, 26.3 � 1.6 pg/dL, and 33.1 � 1.7 g/dL, respectively. The percentages of RDW and Hb E were 14.2 � 0.9% and 29.1 � 3%, respectively. All were negative for inclusion bodies.

In [alpha]-thalassemia^sub 1^ trait subjects, the mean values of Hb and Hct were 13.9 � 0.9 g/dL and 43.8 � 2.3%, respectively. The mean values of MCV, MCH, and MCHC were 69.9 � 2.1 fl, 22.2 � 0.6 pg/dL, and 31.8 � 0.9 g/dL, respectively. The percentages of RDW and Hb A^sub 2^ were 15.9 � 1.2% and 2.2 � 0.6%, respectively. All subjects were positive for inclusion bodies and confirmatory tests (DNA analysis of the [alpha]-thalassemia^sub 1^ gene).

In [beta]-thalassemia trait subjects, the mean values of Hb and Hct were 13.3 � 1.0 g/dL and 41.6 � 2.2%, respectively. The mean values of MCV, MCH, and MCHC were 61.2 � 1.4 fl, 19.5 � 0.7 pg/dL, and 31.9 � 0.9 g/dL, respectively. The percentages of RDW and Hb A^sub 2^ were 16.2 � 0.6% and 5.2 � 0.6%, respectively. All were negative for inclusion bodies. The laboratory results for homozygous Hb E and [beta]/E disease subjects are shown in Table II.

In 21 normal female subjects, the mean values of Hb and Hct were 12.9 � 1.4 g/dL and 38.2 � 4.2%, respectively. The mean values of MCV, MCH, and MCHC were 88.9 � 4.1 fl, 30.1 � 1.6 pg/dL, and 33.9 �1.3 g/dL, respectively. The percentages of RDW and Hb A^sub 2^ were 13.4 � 0.6% and 2.6 � 0.4%, respectively. All were negative for inclusion bodies. Hb E trait and [alpha]-thalassemia^sub 1^ trait subjects results are shown in Table III.

Discussion

The present study shows the prevalence of thalassemia among RTA medical cadets. The most common type in both genders is Hb E trait, which is similar to previous findings in Thailand and other Southeast Asian countries.1-3 In general, healthy individuals who carry the Hb E trait cannot be distinguished by routine CBC; only MCV is slightly decreased. Previous studies introduced the DCIP precipitation test to screen for Hb E;6 nevertheless, we performed Hb typing to determine different types of abnormal Hb. Additionally, homozygous Hb E was detected in two male RTA medical cadets. We found not only an abnormality of Hb E, but also slightly low values of Hb, Hct, and RBC indices. Confirmation of the [alpha]-thalassemia^sub 1^ gene by DNA analysis was carried out in all subjects who were positive for inclusion bodies and showed a decrease in MCV. Unfortunately, the determination of the [alpha]-thalassemia^sub 2^ gene was not included; this may reflect the low prevalence of the [alpha]-thalassemia gene in this study. In addition, two cases of normal female subjects were found to have slightly decreased Hct and Hb, but MCV and MCH were normal, which may be due to inadequacy of iron or other anemic causes.17

With regard to the [beta]-thalassemia trait group, we found abnormal RBC indices with increased percentages of the Hb A^sub 2^ level. One study showed that the OF test and/or abnormal electrophoretic pattern can be used as a screening test for thalassemia in Hellenic Army recruits.5 A combination of the OF test and the DCIP precipitation test was beneficial in screening for the Hb disorder in pregnant Thai women.6 The OF test showed a high sensitivity for [alpha]- and [beta]-thalassemia screening, whereas the DCIP precipitation test was effective for the detection of Hb E disorders. Both tests are useful for mass screening because of their simplicity and speed. However, further tests are needed to ensure more accurate results.7,8,18