Clinics in Mother and Child Health

Abstract

The Value of Red Blood Cells (Rbc) Indices and Osmotic Fragility Test as Screening Tests in Malay Pregnant Women with Alpha Thalassaemia

Rosline Hassan1, Nurul Ain Fathma Abdullah1, Rosnah Bahar1, Selamah Ghazali1 and Nor Aliza Abdul Ghaffa

Red blood cell (RBC) parameters obtained from hematology analyser has been very useful as the first line screening for thalassaemia. The changes are prominent in most type of β-thalassaemia but milder in α-thalassaemia. RBC parameters could have been normalized especially during pregnancy and in such situation screening these patients would require a different protocol. Blood samples from two hundred (200) Malay pregnant women attended obstetric clinic at Hospital Universiti Sains Malaysia (HUSM) were collected to screen for double α-gene deletion (-SEA, and –THAI), and the two single α-globin gene deletion (–α3.7 and -α4.2). Standard hematological analyses including red blood cell count and indices, and hemoglobin quantitation were performed on the blood samples. Of these, sixteen were excluded as they had HbA2 levels more than 4% and were diagnosed as HbE or β-thalassaemia trait. Then, multiplex GAP polymerase chain reaction (PCR) analyses of α-globin gene were performed on the remaining 184 blood samples. Total of 17 from 184 subjects confirmed to have α-thalassaemia (-α3.7/αα and --SEA/ αα genotype). The RBC indices were compared between those with α-thalassaemia and normal pregnant women and they were significantly different. -α3.7 kb single gene deletion (8.1%) was the commonest type followed by double gene South East Asia (--SEA) deletion (1.1%). We conclude that mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) with the cut off value of less than 86.3fl and 27.4 pg respectively are two useful RBC indices which can be used for screening of α-thalassaemia in pregnant women.