Development of Lyophilized Control Material for G6PD Quantitative Point-of-Care Testing

G6PD deficiency affects approximately 500 million people globally, necessitating enzymatic screening before antimalarial treatment to prevent drug-induced hemolysis. Despite the expansion of quantitative point-of-care testing (POCT), standardized lyophilized controls are still limited. This study aims to develop these materials to ensure diagnostic accuracy and support EQA program. Control materials were prepared from G6PD-normal and deficient packed red blood cells (PRBCs). PRBCs were washed and mixed with 5% (w/v) sucrose at the optimized 1:5, 1:10, 1:15 and 1:20 ratios. G6PD activity and hemoglobin (Hb) levels were quantified using the STANDARD™ G6PD test. Stability was evaluated at 4 and -20°C through 6 months. The 1:20 formulation demonstrated optimal reconstitution and clear phenotype differentiation. At 4°C, G6PD activity of G6PD normal control materials remained stable for 1 month followed by a fluctuation below the normal threshold at month 2 (3.9 U/g Hb) while at -20°C, it maintained stability for up to 6 months, despite a gradual decline to 4.0 U/g Hb. Whereas the G6PD deficient control materials exhibited remarkable stability at both temperatures. In addition, Hb levels appeared relatively stable across all tested conditions throughout the 6-month period. In conclusion, lyophilized G6PD control materials with 5% sucrose solution at a 1:20 ratio are suitable for quantitative POCT. For long-term stability, -20°C storage is recommended. This material provides a robust foundation for developing EQA programs compliant with ISO/IEC 17043:2023, ensuring reliable G6PD quantitative Point-of-Care testing.