G6PD enzyme activity in normal term neonates and adults using OSMMR-D kit with HB normalisation

Abstract

Background Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common cause of neonatal jaundice in South East Asia. Screening of cord blood for G6PD deficiency by the semiquantitative fluorescent spot test can miss cases of partial G6PD deficiency. Enzymes quantitation using colorimetric method is relatively simple, and able to quantitate the level of the enzymes. We evaluated the method of enzyme quantitation using OSMMR-D kit with haemoglobin (Hb) normalisation and established the normal range of G6PD activity for the normal term neonates and adults. Methods The blood sample was mixed with 75 µL of elution buffer in a well of microplate. The microplate was slowly warmed to 37°C. After incubation for 8 min, the microplate was read at 405 nm for Hb evaluation. Then, colour reagent mixture (OSMMR-D kit, Greece) was added and the microplate was read again at 550 nm at 0 min, then at 10 min. The results are directly expressed in U/g Hb. Blood samples from a total of 106 neonates and 281 adults (aged between 15 and 59 years) were randomly selected for enzyme quantitation. Results All cases showing bright activity with fluorescent spot test demonstrated normal level of G6PD activity with mean of 12.43 U/g Hb for neonates and 9.35 U/g Hb for adults. There was no significant difference in the mean normal G6PD activity between the two racial groups (Malays and Chinese) as well as between the genders. The reference range for normal G6PD activity is 10.15–14.71 U/g Hb for neonates and 6.75–11.95 U/g Hb for adults. Conclusions This study has established the normal range for the G6PD level in normal term neonates and adults. The quantitation of G6PD enzymes using OSMMR-D kit with Hb normalisation was simple since the Hb was analysed simultaneously and the results were reproducible with CV of less than 5%.