Comparative analysis of diagnostic methods for G6PD deficiency: fluorescent spot test versus quantitative methods

Introduction: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a prevalent enzymopathy with significant public health implications. This study compares the diagnostic performance of the fluorescent spot test (FST), a qualitative method, with two quantitative assays--namely, the World Health Organization (WHO)-recommended method and the Glock and McLean (G&Mc) method--to assess their reliability and applicability. Methods: A total of 221 blood samples collected between 2009 and 2021 were analyzed. Hemolysates were prepared under controlled conditions to preserve enzyme activity. Quantitative assays measured nicotinamide adenine dinucleotide phosphate(NADPH) production using spectrophotometry, while the FST provided visual confirmation under ultraviolet light. Median G6PD activities were calculated, and the sensitivity and specificity of the FST were evaluated against activity thresholds defined by the quantitative methods. Results: The adjusted male median G6PD activity was 12.6 IU/gHb for the WHO method and 8.8 IU/gHb for the G&Mc method. The FST exhibited high sensitivity and specificity across different thresholds, with near-perfect performance at 30% activity and above. Conclusion: The FST is a reliable tool for field-based screening of G6PD deficiency, demonstrating robust sensitivity and specificity. Quantitative methods offer enhanced precision for detailed evaluations, supporting their complementary roles in diagnostics.