Effective screening for double heterozygosity of Hb E/alpha0-thalassemia.
One hundred and forty-one blood samples of hemoglobin E (Hb E) carriers were collected to define suitable cutoff values of Hb E level, mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH) as screening indicators for detecting individuals with double heterozygosity for Hb E/alpha(o)-thalassemia. Based on the values that gave 100% sensitivity, Hb E < 26%, MCV < 74 fl, and MCH < 24 pg were selected. Further validation of these selected values in additional 152 heterozygous Hb E pregnant women revealed 100% sensitivity, 86.2% specificity, and a 25.9% positive predictive value (PPV) for using Hb E cutoff point only, meanwhile, 100% sensitivity, 83.4% specificity, and 22.6% PPV were achieved for the MCV cutoff point. In addition, 100% sensitivity, 86.3% specificity, and 25.9% PPV were gained for the MCH cutoff point. Combining Hb E level with either MCV or MCH cutoff points, the specificity and PPV were increased to 95.1% and 50.0%, respectively. It is concluded that Hb E level < 26%, MCV < 74 fl, and MCH < 24 pg could be used for screening alpha(o)-thalassemia in heterozygous Hb E. However, to improve specificity and PPV of the tests, a combination of Hb E level < 26% with either MCV < 74 fl or MCH < 24 pg is recommended.
Faculty of Associated Medical Sciences, Centre for Research and Development of Medical Diagnostic Laboratories, Khon Kaen University, Khon Kaen 40002, Thailand. kanokwan@kku.ac.th
Kanokwan
K
Sanchaisuriya
Sunisa
S
Chirakul
Hataichanok
H
Srivorakun
Goonnapa
G
Fucharoen
Supan
S
Fucharoen
Yossombat
Y
Changtrakul
Pattara
P
Sanchaisuriya
D004909:Erythrocyte Indices; D005260:Female; D006580:Genetic Carrier Screening / Q000379:methods*; D006446:Hemoglobin E / Q000032:analysis / Q000235:genetics; D006801:Humans; D008403:Mass Screening / Q000379:methods; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D012016:Reference Values; D012680:Sensitivity and Specificity; D017085:alpha-Thalassemia / Q000235:genetics*
D006446:Hemoglobin E