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| ORIGINAL ARTICLE |
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| Year : 2017 | Volume
: 2
| Issue : 2 | Page : 137-142 |
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Evaluation of glucose-6-phosphate dehydrogenase enzyme deficiency and methemoglobin concentration in blood donors in a Nigerian Tertiary hospital-based blood bank
John C Aneke1, Nancy C Ibeh2, Chide E Okocha1, Ebelechukwu Orakpor2
1 Department of Haematology, College of Health Sciences, Nnamdi Azikiwe University, Nnewi, Anambra State, Nigeria
2 Department of Medical Laboratory Science, College of Health Sciences, Nnamdi Azikiwe University, Nnewi, Anambra State, Nigeria
| Date of Web Publication | 11-Sep-2017 |
Correspondence Address:
John C Aneke
Department of Haematology, College of Health Sciences, Nnamdi Azikiwe University, Nnewi, Anambra State
Nigeria
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/GJTM.GJTM_21_17
Background: Glucose-6-phosphate dehydrogenase (G6PD) enzyme deficiency and methemoglobinemia adversely impact on blood transfusion safety by significantly increasing blood storage lesion. Objective: To determine G6PD enzyme deficiency and methemoglobin levels among blood donors in a tertiary hospital-based blood bank in Nigeria. Subjects and Methods: One hundred blood donors who met the criteria for blood donation were prospectively studied. Two milliliters of venous blood was collected from each participant into potassium-ethylenediaminetetraacetic acid specimen containers and analyzed for G6PD status and methemoglobin levels by spectrophotometry, on the same day of sample collection. Results: Among the donors, 43% had normal G6PD activity (9.32 ± 2.26 U/gHb), 44% had partially enzyme deficiency (4.92 ± 1.33 U/gHb), while 13% had total deficiency (0.47 ± 3.49 U/gHb); these were statistically different (P < 0.001). Methemoglobin concentration was elevated in 25% of study participants (3.05 ± 2.30%), while it was normal in 75% (0.99% ± 0.60%); these differences were statistically different (P < 0.001). Conclusion: A significant proportion of our blood donor set has G6PD enzyme deficiency (partial or total) as well as evidence of oxidation of hemoglobin; these findings have adverse implications on transfusion safety.
Keywords: Blood donors, oxidant injury, red cell enzyme, transfusion safety
How to cite this article:
Aneke JC, Ibeh NC, Okocha CE, Orakpor E. Evaluation of glucose-6-phosphate dehydrogenase enzyme deficiency and methemoglobin concentration in blood donors in a Nigerian Tertiary hospital-based blood bank. Glob J Transfus Med 2017;2:137-42 |
How to cite this URL:
Aneke JC, Ibeh NC, Okocha CE, Orakpor E. Evaluation of glucose-6-phosphate dehydrogenase enzyme deficiency and methemoglobin concentration in blood donors in a Nigerian Tertiary hospital-based blood bank. Glob J Transfus Med [serial online] 2017 [cited 2023 Mar 30];2:137-42. Available from: https://www.gjtmonline.com/text.asp?2017/2/2/137/214275 |
| Introduction | |  |
Blood transfusion is an important component of curative and preventive medicine and is equally a significant contributor to global health indices. It is crucial that adequate red cell survival (posttransfusion) is maintained, as this is of importance to good transfusion practices and optimal hematocrit recovery in transfusion recipients. Intracorpuscular defects in the red blood cell have been shown to be intimately linked with its survival and resistance to varying degrees of stress.[1]
Glucose-6-phosphate dehydrogenase (G6PD) is the most common human enzymopathy known globally, and in Sub-Saharan Africa, prevalence rate as high as 32.5% has been reported.[2] In addition to the high prevalence rates reported in Africa, G6PD deficiency has also been observed to affect individuals of Asian, Mediterranean, Middle-Eastern, and Latin American descents.[2],[3] Affected individuals are particularly prone to oxidative red cell damage, arising from their inability to protect red cells against oxidative stresses generated during normal body metabolism or following the ingestion of certain foods or drugs.[4]
Methemoglobin is a metalloprotein hemoglobin, which is formed following the oxidation of the iron in heme to the ferric state. Unlike hemoglobin, methemoglobin cannot adequately transport oxygen; therefore, marked tissue hypoxemia (functional anemia) could occur when it is present in the blood in high concentrations.[5]
In transfusion medicine, significant storage lesions could occur in the presence of intrinsic donor red cell defects and this could adversely impact on the quality of donor units and over all transfusion safety.[6] Blood donors who have high blood levels of methemoglobin or are negative for the G6PD enzyme are generally asymptomatic; consequently, these individuals are frequently missed during donor selection, leading to increase in donor units with potential to develop blood storage lesions.
In red cell exchange for neonatal hyperbilirubinemia, it has been observed that exchanges done with G6PD deficient red cells resulted in less effective clearance of serum bilirubin, due to exacerbated hemolysis which occurred postexchange.[7] Consequently, donor screening for G6PD deficiency is increasingly advocated for neonatal red cell exchange as well as in a number of other disease states which are pathogenetically linked with increased red cell destruction.[7]
There is a paucity of literature on the G6PD status and methemoglobin concentrations in potential blood donors in South-East Nigeria, despite the high general population prevalence of G6PD deficiency in the country. This study was therefore designed to evaluate the G6PD activity and methemoglobin levels in potential blood donors in a tertiary hospital-based blood bank in South-East Nigeria.
| Subjects and Methods | | |
Study area
This study was carried out at the hematology and blood transfusion unit of Nnamdi Azikiwe University Teaching Hospital (NAUTH), Nnewi, Nnewi North Local Government Area, Anambra State, Nigeria. The NAUTH is a tertiary health-care facility serving the high-, low-, and middle-income populations of Nnewi and its environs. Nnewi is a commercial town, divided into four major villages, namely, Umudim, Uruagu, Nnewichi, and Otolo; the languages of communication in the town are Igbo and English.
Study design
This cross-sectional research is designed to study 100 prospective blood donors who presented at NAUTH Nnewi, Anambra State, Nigeria, and satisfied the criteria for blood donation. A convenient sampling method was employed until the sample size was achieved. Each participant had 2 ml of venous blood collected following standard protocols for venesection, into potassium ethylenediaminetetraacetic acid specimen containers, for the estimation of G6PD activity and blood methemoglobin concentration. All the samples were analyzed the same day of sample collection.
Study population
The sample population was 100 blood donors, both males and females within the age of 18 years to 60 years.
The sample size was calculated using the method described by Naing et al.:[8]
n = Z2P(1 − P)/d 2
(1.96)2(0.06)(1 − 0.06)/(0.05)2 = 86
where,
n is the desired number of samples.
Z is the desired number of variation, usually set at 1.96 which corresponds to 95% confidence level.
P is the expected prevalence or proportion of attribute present in the population. The prevalence of G6PD deficiency in Nigeria ranges from 4% to 26%.[9]
d is the precision, usually set at 0.05.
Ethical consideration
The ethical clearance for this research was obtained from the NAUTH' Ethical Committee. Oral informed consent was obtained from the blood donors at the point of recruitment, according to the Helsinki declaration on researches that involve human subjects.
Inclusion and exclusion criteria
- Inclusion criteria: All blood donors who satisfied the screening for blood donation
- Exclusion criteria: Blood donors who are under specific medications such as antihypertensives (α-methyldopa) which could exacerbate red cell lysis and those known or suspected to have underlying hemoglobinopathy.
Sample analysis
The G6PD activity was determined following the protocol of Lohr and Waller,[10] which is based on the measurement in the rate of change of absorbance at 340 nm due to the reduction of oxidized nicotinamide adenine dinucleotide phosphate (NADP +). The test kits used were manufactured by RANDOX Laboratories ®; these have inbuilt sensitivity (minimum precision level) of 156 U/L and 98% accuracy.[11] The designation for normal enzyme activity was between 6.97 and 20.50 U/gHb.[11]
Blood methemoglobin concentration was estimated based on the method described by Lewis and Roper,[12] by adding 2 ml of 0.1 M phosphate buffer to 100 μl of whole blood followed by the addition of 250 ul of 4% potassium ferricyanide. The absorbance of the reaction mix was read spectrophotometrically after 10 min, at 630 nm wavelength. The classification of blood methemoglobin concentration (into high or low) was as follows: ≤2% is normal and ≥2% is high.[5]
RANDOX ® control samples were used during the testing for G6PD enzyme activity while pooled blood samples from apparently healthy controls were used to control the assay for blood methemoglobin levels.
Statistical analysis
Statistical Package for the Social Sciences (SPSS) version 21.0 (SPSS Inc., Chicago, IL, USA) was used for all data analyses. Results were expressed as means ± standard deviations while comparison of means was done using the Student's t-test and/or analysis of variance. The level of statistical significance was set at P < 0.05.
| Results | | |
One hundred prospective blood donors were studied (aged 18–60 years); 39% of the donors were aged 18–25 years, 36% were 26–35 years, 11% were in the 36–45 years, while 14% were aged 46 years and above [Table 1]. The gender distribution of the study participants included 85% males and 15% females [Table 1].
The ABO blood group distribution of the study participants included 70% (blood group O), 22% (blood group A), and 8% (blood group B) [Table 2].
The G6PD status of participants is shown in [Table 3]; 43 participants had normal enzyme activity (9.32 ± 2.26 U/gHb), 44 had partial deficiency (4.49 ± 1.33 U/gHb), while 13 had total deficiency (0.47 ± 3.49 U/gHb). These differences were statistically significant (P < 0.001).
Methemoglobin concentration was elevated in 25% of the participants (3.03% ± 2.30%), while 75% had normal blood level (0.99% ± 0.60%); these differences were statistically different (P < 0.001) [Table 4].
There were no significant differences in G6PD enzyme status and blood methemoglobin concentration in study participants when compared to gender [Table 5], blood group, and age distribution (P > 0.05). The hemoglobin concentration of study subjects was significantly higher in subjects with G6PD enzyme deficiency compared with those with normal activity (P = 0.03; [Table 6]). There was no difference in enzyme activity when compared by blood group in study subjects [Table 7] and no significant correlation between G6PD enzyme status and blood methemoglobin level in all study participants (r = 0.34; P = 0.12). | Table 5: Comparison of glucose-6-phosphate dehydrogenase enzyme activity, hemoglobin concentration, and methemoglobin levels of participants by gender
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 | Table 6: Comparison of methemoglobin levels and hemoglobin concentration by glucose-6-phospahate dehydrogenase enzyme status
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 | Table 7: Comparison of glucose-6-phosphate dehydrogenase enzyme activity, hemoglobin concentration, and methemoglobin levels of study participants by with the ABO blood group
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| Discussion | | |
Donors within the 18–25 years age group had the highest representation in this study (39.0%) [Table 1]; this pattern of donor distribution is in agreement with the report of Bolarinwa et al. in Ile-Ife, South West Nigeria, and represents the most active age stratum of the population.[13]
The prevalence rate of G6PD deficiency is known to differ widely among different population groups, being dependent on racial/ethnic composition as well as other sociogeographical determinants. Indeed, the prevalence rates ranging from 3.4% in the Americas to 3.9%, 2.9%, 7.5%, 6.0%, and 4.7% in Europe, the Pacific, Sub-Saharan Africa, the Middle East, and Asia, respectively, have been reported.[14] In this study, the prevalence of total G6PD deficiency was 13% among our blood donor population [Table 2]; this is keeping with reports from other parts of Nigeria. In North Central Nigeria, Egesie et al. showed that 20% (26 out of 130) of blood donors had deficient G6PD enzyme activity, while in Osogbo, South West Nigeria, Akanni et al. reported the prevalence rate of 19.5%.[15],[16] The high prevalence of G6PD deficiency observed in this study (and in other studies from different parts of Nigeria) could be linked to the high prevalence of malaria infection. Individuals who are G6PD deficient have been shown to have significant survival advantage against severe forms of Plasmodium falciparum malaria; this is thought to be due to impaired maturation of malaria parasite in G6PD deficient red cells.[17]
The gender distribution of our study population showed that 12 (92.3%) of the G6PD deficient donors were males while 1 (7.7%) were females; additionally, 89.7% of all donors were males, while 10.3% were females. Similar (predominantly male) demographic patterns have been replicated in earlier studies in parts of Nigeria and Africa.[13],[16],[17],[18],[19],[20] The above observation is equally in keeping with the fact that G6PD deficiency is an X-linked disorder and so predominates in male participants.
In this study, even though blood group B donors showed the highest level of G6PD activity (6.99 ± 3.85 U/Hg) compared with others, this relationship was not statistically different. The above observations are in keeping with an earlier report which evaluated the G6PD activity of stored blood and emphasized that the different blood groups of study participants did not show any significant variation in their G6PD activity.[21]
Under normal physiologic conditions, blood methemoglobin levels are well regulated (<1%) by the action of the methemoglobin reductase enzyme system (mainly the NADH-cytochrome b5 reductase).[22] However, in a number of infectious and noninfectious conditions (including malaria parasitemia, ingestion of nitrate containing compounds, and certain drugs), the protective action of these enzyme systems could become overwhelmed, leading to acute increase in blood methemoglobin levels.[23] In this study, 25% of our donor set had elevated blood methemoglobin levels (3.05% ± 2.30%) compared with 75% who had normal blood levels (0.99% ± 0.60%); these differences were significantly different [P < 0.001; [Table 4]. Zama et al. in Sokoto, North-West Nigeria, and Okeke et al. in Nnewi, South East Nigeria, independently reported high prevalence rates of asymptomatic malaria infection in 2 donor populations (32.5% and 75.0%, respectively).[24],[25] These observations most probably account for the high blood methemoglobin levels observed in this study, as intracellular malaria parasites have been shown to possess the ability to spontaneously convert iron (Fe2+) to ferric (Fe3+) within food vacuoles.[5] Asymptomatic malaria infection of potential donors has therefore gained renewed significance in transfusion safety because increased blood levels of methemoglobin are known to be associated with various potentially fatal complications such as cyanosis, change in mental status, and even death.[5] This is because in the presence of G6PD deficiency, there is insufficient supply of NADPH for the NADPH-dependent methemoglobin reductase enzyme, which catalyzes the reduction of preformed methemoglobin to oxyhemoglobin.[26] This often results in exaggerated red cell destruction, especially in the presence of oxidant stress. Even though our study conditions did not involve the introduction of oxidant stress, it is likely that the increased loss of methemoglobin containing red cells (in response to oxidant challenge) in G6PD enzyme deficient donors could have accounted for the lack of significant difference in blood levels of methemoglobin of study participants, when compared with their G6PD enzyme status (P = 0.59) [Table 6]. The hemoglobin concentration of study participants was significantly higher in those with partial and total G6PD enzyme deficiency compared with those with normal activity (P = 0.03) [Table 6]; this may be related to the reticulocyte response which could accompany low-grade red cell lysis encountered in methemoglobinemia.[22]
| Conclusion | | |
The high frequency of G6PD enzyme deficiency and elevated blood methemoglobin level observed in the donor set may indicate that a number of our donor units could have significant storage lesion and may be of limited usefulness in transfusions for neonatal hyperbilirubinemia, sickle cell disease (SCD), as well as in G6PD deficient recipients.
Recommendation
Consideration should be given to the routine screening of all donor units to be transfused to neonates (particularly for hyperbilirubinemia), SCD and G6PD negative recipients, for G6PD enzyme deficiency and methemoglobinemia. The CareStart G6PD Rapid Diagnostic Test (CSG; AccessBio, USA) is fast and can be properly adapted for use in routine blood bank testing. This could reduce the potential blood storage lesions that follow the collection of such units and improve transfusion safety. More research should be carried out on this study, with larger population of blood donors, to confirm these findings.
Limitation of the study
Malaria parasitemia was not accessed in this study, particularly in donors with high blood methemoglobin levels.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]
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