A “One-Stop” Screening Protocol for Haemoglobinopathy Traits and Iron Deficiency in Sri Lanka

Abstract

Introduction: The high frequencies of carriers of severe haemoglobinopathies and of iron deficiency in Southeast Asia require reliable and affordable tests to improve on current screening procedures. Objectives: We evaluate a “one stop” approach using the THALCON dichlorophenolindophenol (DCIP) and one-tube osmotic fragility (OF) tests and measurement of Zinc Protoporphyrin (ZPP) to detect and distinguish HbE and β-thalassaemia traits from iron deficiency. We compare findings with current screening practice in Sri Lanka that relies on the identification of low mean red cell volume and/or mean red cell hemoglobin for this purpose. Methods: Between November 2017 and May 2018, we undertook a cross-sectional survey of secondary school students in Gampaha district, Sri Lanka. The THALCON–DCIP and OF tests were compared to capillary electrophoresis (CE), used as a gold standard to detect haemoglobinopathies. ZPP was measured in whole blood. Plasma ferritin and C-reactive protein (CRP) were measured in students with a raised ZPP concentration. Results: We collected venous blood samples from 1,324/1,332 (99.4%) students. The median age of the students was 17 (IQR 16–18) years, all were Sinhalese and 814/1,324 (61.5%) were female. CE identified 3 students with HbE trait and 26 students with β-thalassaemia trait. The THALCON–DCIP test was positive only in the 3 students with HbE (sensitivity 100%, 95% CI 29.2–100.0; specificity 100%, 95% CI 99.7–100.0). The THALCON–OF test identified all 26 students with β-thalassaemia trait (sensitivity = 100%, 95% CI 86.8–100.0) and 287 students with a normal CE result (specificity = 77.9%; 95% CI 75.5–80.1). It was also positive in 2/3 (66.7%) students with HbE trait. Iron deficiency (ZPP > 70 μmol/mol heme) was present in 118/1,240 (9.5%) students with a normal hemoglobin genotype, all of whom had plasma ferritin <15 ng/ml and CRP <5 mg/L. Conclusion: This one–stop approach offers reliable and affordable population screening for both haemoglobinopathy traits and iron deficiency in resource-limited settings where these conditions are common and ensures that iron supplements are targeted only to those who require them. Further work is warranted to refine the OF test to reduce the number of false positive results.

Knowledge and practices on childhood anaemia, thalassaemia and iron deficiency among mothers of children aged between 6 and 59 months in a suburban area of Sri Lanka

“…The facilities for screening for thalassaemia are available throughout the country for free [ 31 , 32 ]. The low figure reported in our study highlights that despite its existence for over 15 years, the National Thalassaemia Prevention Programme has not been able to deliver the message to the public [ 12 ]. In a recent study done among 245 females diagnosed with anaemia during pregnancy, we found that 18 had undiagnosed β-thalassaemia trait, which was not recognised up to the pregnancy [ 33 ].…”

“…Thalassaemia trait is an asymptomatic condition which results in mild microcytic anaemia [ 11 ]. It does not require any treatment; however, the affected individuals should avoid marrying a partner with thalassaemia trait to prevent the birth of a child with severe homozygous forms of thalassaemia (thalassaemia major) [ 12 ]. The prevalence of β- and α-thalassaemia traits in Sri Lanka is reported as 2.8% and 8%, respectively [ 13 , 14 ].…”

Shooting shadows: India’s struggle to reduce the burden of anaemia

“…Several strategies (78) are available and the regional experience in Sri Lanka could be instructive (79) . An advocacy effort might work to gain support for furthering research and development into rapid screening which could test for haemoglobinopathies and Fe deficiency in one test, as demonstrated in a recent study conducted in Sri Lanka (80) .…”