This study attempted to check the reliability of qualitative method of testing G6PD (Methemoglobin reduction test) in reference to the spectrophotometric method and also to find out the frequency of deficient cases among the patient attending UCMS-TH, Bhairahawa, Nepal.
100 subjects were studied in our research and the frequency of G6PD deficient subjects was found to be 3%. In a study by Oni G et al. 60% were male subjects and 40% were female subjects with frequency of G6PD deficient males 40 and that of females 35 in contrast to our study in which, among 52% females and 48% males and all 3 of the deficient individuals were males. [14]
The positive (deficient) results given by both Methemoglobin Reduction Test and Spectrophotometric methods were same that is 3%. The spectrophotometric assay detected 7 individuals to be hyperactive which could only be considered as normal with methemoglobin reduction test. [15] Since our main concern was with deficiency of the enzyme, methemoglobin reduction test was considered as a good method for screening G6PD deficiency.
Suvitha Thilakarajan et al. (2014) stated, in their study that, methemoglobin reduction test was able to pick heterozygous female. Their study tested subjects only with methemoglobin reduction test and suggested to analyze its efficacy with a simultaneous enzymatic assay. On contrast to their study, the present study has adopted both the methods for testing G6PD assay. But in our study, none of the female subjects were found to be G6PD deficient hence we couldn’t predict if Methemoglobin reduction could analyze heterozygous females or not. [16]
The frequency of positive subjects in our study was similar to that found in Dhanusa district in previous study by Lamichanne N et al. (2017) where it was 3.1%. While it was different than prevalence in other districts like Jhapa where it was 9.8%, in Morang district where it was 5.8%. Our study was hospital based unlike their study. The samples in our study were suspected cases of G6PD deficient patients attending UCMS-TH only which could be low as compared to the susceptible patients of G6PD deficiency regions. [17]
The mean ± SD of G6PD activity in the sample population was 15.69 ± 4.23 U/gHb in our study which is quite different than that of Kim S et al. (2011) who projected 10.9 ± 4.6 U/g Hb. Since the study done by them was in different region of Asia i.e. in Cambodia which may vary G6PD enzyme activity geographically. Moreover, their method of assay was different from our study. They performed the tests using CareStart™, a rapid diagnostic test method for G6PD screening while ours was according to G-Six Kinetic Assay, Tulip Group, India, by Spectrophotometric assay. [18]
The male subjects having G6PD deficiency outnumbered the number female subjects in our study, similar to the study by Das K P et al. (2013) in which all the deficient subjects were males and the study conducted by Gautam N et al. (2019) in which 81.8% of the deficient subjects were males. [19, 20]This suggests the fact that G6PD deficiency is an x-linked genetic disorder and males are more prone to be affected than females.
In our study, the frequency of subjects having increased enzyme activity was 7% which is very similar to the result obtained by Khim et al. (2013) in which they have 5.1% of subjects considered in Class V which WHO classifies as a class of individuals having an increased activity of G6PD enzyme. [21, 22] According to Domingo G J et al. high count of young red cells or high leukocyte count might result in high G6PD activity because G6PD level is higher in these cells which supports our study in a way that all the subjects with hyperactivity of enzyme were having an increased level of reticulocyte count. [23]
The reticulocyte count was higher in the G6PD deficient subjects similar to result of Al-Nood AH et al. (2011), but in our study, the reticulocyte count was higher in all the subjects with hyperactive enzyme status. The mean ± SD of reticulocytes was 1.62 ± 0.90 and P-value was 0.004. [24] In our study 25% of the subjects were having high reticulocyte count and remaining 75% had a normal count.
The G6PD activity was statistically correlated with RBC count with P-value of 0.048 in our study while with PCV there was no significant correlation found. Since the G6PD deficiency precipitates the hemolysis with other factors that might have caused the RBC count to be significantly reduced. Also we didn’t find any statistical association between hemoglobin level and G6PD.