The effect of different haemoglobins on the glucose-6-phosphate dehydrogenase deficiency screening test (Brewer's test)

R Sugathadasa,Dm Dissanayake

doi:10.4038/jdp.v5i1.2957

Abstract

Glucose-6-phosphate dehydrogenase (G6PD) deficiency and haemoglobinopathies are common causes of haemolytic anaemia in Sri Lanka. Even though G6PD enzyme assay is indicated for diagnosis of G6PD deficiency, due to lack of reagents many of the government hospitals in Sri Lanka make the diagnosis only on the basis of a screening test (Brewer's test) for this deficiency. Both these tests are indicated in patients with chronic haemolytic anaemia. The aim of the study was to observe the effect of different haemoglobins on screening test for G6PD deficiency. We investigated the patients and carriers for commoner haemoglobinopathies (Hb E, Hb S, and Hb D) and thalassaemias using G6PD deficiency screening test as well as G6PD enzyme assay. The results show that patients with Hb E/β thalassaemia, Hb E trait and Hb E disease gave a false positive reaction with G6PD screening test (n=47), even though their G6PD enzyme levels were normal. Two subjects with Hb E showed low enzyme levels with positive screening test. Hb S (n=5) and Hb D (n=2) did not have any effect on the screening test for G6PD deficiency. The patients with Hb E and normal enzyme levels are likely to be misdiagnosed as having G6PD deficiency, if only the screening test is utilized. This study emphasizes the necessity for employing an enzyme assay method for the diagnosis of G6PD deficiency, at least in districts with high Hb E prevalence. Keywords: G6PD; Brewer's test; thalassaemia; haemoglobinopathy. DOI: 10.4038/jdp.v5i1.2957 Journal of Diagnostic Pathology 2006/07; 5: 30-34

Highlights

Glucose 6 phosphate dehydrogenase (G6PD) deficiency is the commonest enzymopathy causing haemolytic anaemia in human beings
The results show that Hb E present in Hb E/ thalassaemia, Hb E trait and Hb E disease, gives a false positive reaction with G6PD screening test, even though their G6PD enzyme levels were normal
The present study demonstrates that the patients with Hb E give false positive results with a screening test for G6PD

Summary

Introduction

Glucose 6 phosphate dehydrogenase (G6PD) deficiency is the commonest enzymopathy causing haemolytic anaemia in human beings. Haemoglobin E which is the commonest haemoglobinopathy in Sri Lanka is more prevalent in Kurunegala, Kandy, and Badulla and in Anuradhapura districts. Beta thalassaemia major is more prevalent in Kurunegala Kandy, Badulla and Anuradhapura districts.[1] The haemoglobinopathies and thalassaemic syndromes causing chronic haemolytic anaemia in Sri Lanka include thalassaemia major, thlassaemia intermedia, Hb E/ thalassaemia, Sickle cell anaemia, Hb S/ thalassaemia and Hb D/ thalassaemia. In some Thalassaemic syndromes the patients may need special treatment to prevent iron overload while this is not indicated in G-6-PD deficiency

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