Evaluation of stability and potential interference on the α-thalassaemia early eluting peak and immunochromatographic strip test for α-thalassaemia --SEA carrier screening.

Abstract

Objectives: α-Thalassaemia screening is crucial for identifying carriers at risk of having offspring with haemoglobin (Hb) Bart's hydrops fetalis syndrome. This study evaluated the performance of two potential screening methods: the α-thalassaemia early eluting peak (αEEP) identified by high-performance liquid chromatography (HPLC) and an immunochromatographic strip test (ICT), focusing on stability and potential interferences.

Methods: Ninety-two peripheral blood samples were used. Thirty were for assessment of αEEP and ICT stability and interference by icterus/lipaemia, and saline washing for interference removal. Diagnostic performance of αEEP and ICT were evaluated in 40 samples with glycated Hb (P2) ≥6.0 % and 22 with Hb F≥2.0 % on HPLC, using α-globin genotyping as the gold standard.

Results: Both αEEP and ICT results remained stable for 14 days. Neither test was significantly affected by icterus or lipaemia, though 3 of 20 ICT results (15 %) showed discordance after saline washing. Elevated HbA_1c and Hb F altered early eluting peak patterns but did not affect αEEP interpretation. For detecting --^SEA mutation, αEEP showed 100 % sensitivity and 100 % specificity when P2≥6.0 % or Hb F≥2.0 %, while ICT a low specificity (45 %) when Hb F≥2.0 %.

Conclusions: αEEP showed reliable performance in detecting α⁰-thalassaemia with --^SEA mutation in all conditions tested, while ICT showed low specificity when Hb F≥2.0 %. These findings support αEEP as a reliable test for routine clinical laboratory use, while cautions should be made for ICT in case of elevated Hb F levels.