Comparison of detection of glucose-6-phosphate dehydrogenase deficiency using fluorescent spot test, enzyme assay and molecular method for prediction of severe neonatal hyperbilirubinaemia

Introduction: This study aimed to compare the detection rates of glucose-6-phosphate dehydrogenase (G6PD) deficiency in neonates by fluorescent spot test (FST), enzyme assay and molecular methods, and to identify which method was a significant predictor of severe hyperbilirubinaemia. Methods: 74 term infants of Chinese descent admitted with severe hyperbilirubinaemia (total serum bilirubin equal or greater than 300 micromol/L) and 125 healthy term infants born in the hospital without severe hyperbilirubinaemia were recruited into the study. Specimens of blood were collected from each infant for FST, G6PD enzyme assay and TaqMan (R) minor groove binder single nucleotide polymorphism genotyping assay. Results: 26 (13.1 percent) infants were diagnosed to have G6PD deficiency by FST. They had significantly lower median enzyme levels (0.8 IU/g Hb, interquartile range [IQR] 0.4-4.3) than those diagnosed to be normal (12.0 IU/g Hb, IQR 10.3-15.8) (p-value is less than 0.0001). Based on the enzyme assay, 39 (19.6 percent) infants had G6PD deficiency at an enzyme cut-off level of less than 8.5 IU/g Hb. G6PD mutation was detected in 27 (13.6 percent) infants. Logistic regression analysis showed that the only significant predictors of severe hyperbilirubinaemia were G6PD deficiency based on a cut-off level of less than 8.5 IU/g Hb (adjusted odds ratio [OR] 5.3, 95 percent confidence interval [CI] 2.4-11.4; p-value is less than 0.0001) and exclusive breast-feeding (adjusted OR 11.4, 95 percent CI 3.1-42.4; p-value is less than 0.0001). The gender and birth weight of infants, FST results, G6PD mutation and the actual G6PD enzyme levels were not significant predictors. Conclusion: A G6PD enzyme level of less than 8.5 IU/g Hb is a significant predictor of severe hyperbilirubinaemia.