Contextual factors and G6PD diagnostic testing: a scoping review and evidence and gap map.

BACKGROUND: Testing for glucose-6-phosphate dehydrogenase (G6PD) deficiency is an important consideration regarding treatment for malaria. G6PD deficiency may lead to haemolytic anaemia during malaria treatment and, therefore, determining G6PD deficiency in malaria treatment strategies is extremely important. METHODS: This report presents the results of a scoping review and evidence and gap map for consideration by the Guideline Development Group for G6PD near patient tests to support radical cure of Plasmodium vivax. This scoping review has investigated common diagnostic tests for G6PD deficiency and important contextual and additional factors for decision-making. These factors include six of the considerations recommended by the World Health Organization (WHO) handbook for guideline development as important to determining the direction and strength of a recommendation, and included 'acceptability', 'feasibility,' 'equity,' 'valuation of outcomes,' 'gender' and 'human rights'. The aim of this scoping review is to inform the direction of future systematic reviews and evidence syntheses, which can then better inform the development of WHO recommendations regarding the use of G6PD deficiency testing as part of malaria treatment strategies. RESULTS: A comprehensive search was performed, including published, peer-reviewed literature for any article, of any study design and methodology that investigated G6PD diagnostic tests and the factors of 'acceptability', 'feasibility,' 'equity,' 'valuation of outcomes,' 'gender' and 'human rights'. There were 1152 studies identified from the search, of which 14 were determined to be eligible for inclusion into this review. The studies contained data from over 21 unique countries that had considered G6PD diagnostic testing as part of a malaria treatment strategy. The relationship between contextual and additional factors, diagnostic tests for G6PD deficiency and study methodology is presented in an overall evidence and gap, which showed that majority of the evidence was for the contextual factors for diagnostic tests, and the 'Standard G6PD (SD Biosensor)' test. CONCLUSIONS: This scoping review has produced a dynamic evidence and gap map that is reactive to emerging evidence within the field of G6PD diagnostic testing. The evidence and gap map has provided a comprehensive depiction of all the available literature that address the contextual and additional factors important for decision-making, regarding specific G6PD diagnostic tests. The majority of data available investigating the contextual factors of interest relates to quantitative G6PD diagnostic tests. While a formal qualitative synthesis of this data as part of a systematic review is possible, the data may be too heterogenous for this to be appropriate. These results can now be used to inform future direction of WHO Guideline Development Groups for G6PD near patient tests to support radical cure of P. vivax malaria.

Treatment of Tuberculous Pleurisy With Contezolid in a Child With Glucose-6-Phosphate Dehydrogenase Deficiency: The First Case Report.

This is the first reported case of a pediatric patient with tuberculous pleurisy and glucose-6-phosphate dehydrogenase deficiency treated with contezolid concomitantly with other antituberculous drugs. The patient responded well to treatment, and no adverse events were observed. These findings suggest that contezolid may be a potential therapeutic option for tuberculous pleurisy in children and adolescents with glucose-6-phosphate dehydrogenase deficiency.

G6PD deficiency mediated impairment of iNOS and lysosomal acidification affecting phagocytotic clearance in microglia in response to SARS-CoV-2.

The glucose-6-phosphate dehydrogenase (G6PD) deficiency is X-linked and is the most common enzymatic deficiency disorder globally. It is a crucial enzyme for the pentose phosphate pathway and produces NADPH, which plays a vital role in regulating the oxidative stress of many cell types. The deficiency of G6PD primarily causes hemolytic anemia under oxidative stress triggered by food, drugs, or infection. G6PD-deficient patients infected with SARS-CoV-2 showed an increase in hemolysis and thrombosis. Patients also exhibited prolonged COVID-19 symptoms, ventilation support, neurological impacts, and high mortality. However, the mechanism of COVID-19 severity in G6PD deficient patients and its neurological manifestation is still ambiguous. Here, using a CRISPR-edited G6PD deficient human microglia cell culture model, we observed a significant reduction in NADPH level and an increase in basal reactive oxygen species (ROS) in microglia. Interestingly, the deficiency of the G6PD-NAPDH axis impairs induced nitric oxide synthase (iNOS) mediated nitric oxide (NO) production, which plays a fundamental role in inhibiting viral replication. Surprisingly, we also observed that the deficiency of the G6PD-NADPH axis reduced lysosomal acidification and free radical production, further abrogating the lysosomal clearance of viral particles. Thus, impairment of NO production, lysosomal functions, and redox dysregulation in G6PD deficient microglia altered innate immune response, promoting the severity of SARS-CoV-2 pathogenesis.

Serum microRNAs as new biomarkers for detecting subclinical hemolysis in the nonacute phase of G6PD deficiency.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is one of the most common enzymopathies worldwide. Patients with G6PD deficiency are usually asymptomatic throughout their life but can develop acute hemolysis after exposure to free radicals or certain medications. Several studies have shown that serum miRNAs can be used as prognostic biomarkers in various types of hemolytic anemias. However, the impact of G6PD deficiency on circulating miRNA profiles is largely unknown. The present study aimed to assess the use of serum miRNAs as biomarkers for detecting hemolysis in the nonacute phase of G6PD deficiency. Patients with severe or moderate G6PD Viangchan (871G > A) deficiency and normal G6PD patients were enrolled in the present study. The biochemical hemolysis indices were normal in the three groups, while the levels of serum miR-451a, miR-16, and miR-155 were significantly increased in patients with severe G6PD deficiency. In addition, 3D analysis of a set of three miRNAs (miR-451a, miR-16, and miR-155) was able to differentiate G6PD-deficient individuals from healthy individuals, suggesting that these three miRNAs may serve as potential biomarkers for patients in the nonhemolytic phase of G6PD deficiency. In conclusion, miRNAs can be utilized as additional biomarkers to detect hemolysis in the nonacute phase of G6PD deficiency.

Exchange Transfusion Trends and Risk Factors for Extreme Neonatal Hyperbilirubinemia over 10 Years in Shiraz, Iran.

Background: Exchange transfusion (ET) is an effective treatment for acute bilirubin encephalopathy and extreme neonatal hyperbilirubinemia (ENH). It can reduce mortality and morbidity. This study aimed to investigate the trends and risk factors of ENH requiring ET in hospitalized neonates in Iran. Methods: A retrospective analysis of medical records of neonates who underwent ET due to ENH was conducted from 2011 to 2021, in Shiraz, Iran. Clinical records were used to gather demographic and laboratory data. The quantitative data were expressed as mean±SD, and qualitative data was presented as frequency and percentage. P<0.05 was considered statistically significant. Results: During the study, 377 ETs were performed for 329 patients. The annual rate of ET decreased by 71.2% during the study period. The most common risk factor of ENH was glucose-6-phosphate dehydrogenase (G6PD) deficiency (35%), followed by prematurity (13.06%), ABO hemolytic disease (7.6%), sepsis (6.4%), Rh hemolytic disease (6.08%), and minor blood group incompatibility (3.34%). In 28.52% of the cases, the cause of ENH was not identified. 17 (5.1%) neonates had acute bilirubin encephalopathy, of whom 6 (35.29%) had G6PD deficiency, 6 (35.29%) had ABO incompatibility, and 2 (11.76%) had Rh incompatibility. Conclusion: Although the rate of ET occurrence has decreased, it seems necessary to consider different risk factors and appropriate guidelines for early identification and management of neonates at risk of ENH should be developed. The findings of the study highlighted the important risk factors of ENH in southern Iran, allowing for the development of appropriate prevention strategies.

The effect of single low-dose primaquine treatment for uncomplicated Plasmodium falciparum malaria on haemoglobin levels in Ethiopia: a longitudinal cohort study.

BACKGROUND: To interrupt residual malaria transmission and achieve successful elimination of Plasmodium falciparum in low-transmission settings, the World Health Organization (WHO) recommends the administration of a single dose of 0.25 mg/kg (or 15 mg/kg for adults) primaquine (PQ) combined with artemisinin-based combination therapy (ACT), without glucose-6-phosphate dehydrogenase (G6PD) testing. However, due to the risk of haemolysis in patients with G6PD deficiency (G6PDd), PQ use is uncommon. Thus, this study aimed to assess the safety of a single low dose of PQ administered to patients with G6PD deficiency. METHODS: An observational cohort study was conducted with patients treated for uncomplicated P. falciparum malaria with either single-dose PQ (0.25 mg/kg) (SLD PQ) + ACT or ACT alone. Microscopy-confirmed uncomplicated P. falciparum malaria patients visiting public health facilities in Arjo Didessa, Southwest Ethiopia, were enrolled in the study from September 2019 to November 2022. Patients with uncomplicated P. falciparum malaria were followed up for 28 days through clinical and laboratory diagnosis, such as measurements of G6PD levels and haemoglobin (Hb) concentrations. G6PD levels were measured by a quantiative CareSTART™ POCT S1 biosensor machine. Patient interviews were also conducted, and the type and frequency of clinical complaints were recorded. Hb data were taken on days (D) 7, 14, 21, and 28 following treatment with SLD-PQ + ACT or ACT alone. RESULTS: A total of 249 patients with uncomplicated P. falciparum malaria were enrolled in this study. Of these, 83 (33.3%) patients received ACT alone, and 166 (66.7%) received ACT combined with SLD-PQ treatment. The median age of the patients was 20 (IQR 28-15) years. G6PD deficiency was found in 17 (6.8%) patients, 14 males and 3 females. There were 6 (7.2%) and 11 (6.6%) phenotypic G6PD-deficient patients in the ACT alone and ACT + SLD-PQ arms, respectively. The mean Hb levels in patients treated with ACT + SLD-PQ were reduced by an average of 0.45 g/dl (95% CI = 0.39 to 0.52) in the posttreatment phase (D7) compared to a reduction of 0.30 g/dl (95% CI = 0.14 to - 0.47) in patients treated with ACT alone (P = 0.157). A greater mean Hb reduction was observed on day 7 in the G6PDd ACT + SLD-PQ group (- 0.60 g/dL) than in the G6PDd ACT alone group (- 0.48 g/dL); however, there was no statistically significant difference (P = 0.465). Overall, D14 losses were 0.10 g/dl (95% CI = - 0.00 to 0.20) and 0.05 g/dl (95% CI = - 0.123 to 0.22) in patients with and without SLD-PQ, respectively (P = 0.412). CONCLUSIONS: This study's findings indicate that using SLD-PQ in combination with ACT is safe for uncomplicated P. falciparum malaria regardless of the patient's G6PD status in Ethiopian settings. Caution should be taken in extrapolating this finding in other settings with diverse G6DP phenotypes.

[The Wolf in Sheep's Clothing Leishmania tropica: Two Pediatric Visceral Cases]. / Kuzu Postuna Bürünmüs Kurt Leishmania tropica: Iki Pediyatrik Viseral Olgusu.

According to the World Health Organization (WHO), leishmaniasis is a zoonotic/anthroponotic parasitic disease endemic in 99 countries. It is estimated that approximately 12 million people are infected with Leishmania spp. and 350 million people live at risk. Every year, two million new cases are added to these figures. One and a half million cases of zoonotic/anthroponotic cutaneous leishmaniasis and 500 000 cases of visceral leishmaniasis are reported annually. One person is estimated to to be infected with cutaneous leishmaniasis in every 20 seconds and visceral leishmaniasis causes 60 000 deaths. In this report, two pediatric cases diagnosed with visceral leishmaniasis were presented. In the study, bone marrow aspirations were performed to determine the etiology of the disease in an eight-month-old male patient with fever and hepatosplenomegaly who had been followed up in Manisa Celal Bayar University, Department of Pediatrics, Division of Pediatric Hematology with the diagnosis of severe glucose-6-phosphate dehydrogenase (G-6PD) deficiency since the neonatal period and in a nine-month-old female patient who had had a high fever and bicytopenia for two weeks. Bone marrow aspirations were cultured in NNN medium and their smears were stained and examined with Giemsa. rk-39 and Leishmania IFAT tests were performed by using patients' sera. Quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) analysis was also performed for Leishmania spp. Leishmania spp. amastigotes were observed in Giemsa-stained smear preparations, Leishmania spp. promastigotes were grown in NNN medium, rk39 rapid diagnostic kit was weakly positive, Leishmania IFAT was positive at a titer of 1/1024 and Leishmania tropica was identified as the causative agent by RT-qPCR analysis for both cases. These two cases suggested that fatal cases of visceral leishmaniasis may increase with the spread of visceralized isolates of L.tropica, the most common causative agent of cutaneous leishmaniasis in Türkiye, and this issue may create a significant public health problem.

Glucose-6-phosphate dehydrogenase deficiency as a cause for nonimmune hydrops fetalis and severe fetal anemia: A systematic review.

BACKGROUND: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked recessive disorder that predisposes individuals to hemolysis due to an inborn error of metabolism. We performed a systematic literature review to evaluate G6PD deficiency as a possible etiology of nonimmune hydrops fetalis (NIHF) and severe fetal anemia. METHODS: PubMed, OVID Medline, Scopus, and clinicaltrials.gov were queried from inception until 31 April 2023 for all published cases of NIHF and severe fetal anemia caused by G6PD deficiency. Keywords included "fetal edema," "hydrops fetalis," "glucose 6 phosphate dehydrogenase deficiency," and "fetal anemia." Cases with workup presuming G6PD deficiency as an etiology for NIHF and severe fetal anemia were included. PRISMA guidelines were followed. RESULTS: Five cases of G6PD-related NIHF and one case of severe fetal anemia were identified. Four fetuses (4/6, 66.7%) were male and two fetuses (2/6, 33.3%) were female. Mean gestational age at diagnosis of NIHF/anemia and delivery was 32.2 ± 4.9 and 35.7 ± 2.4 weeks, respectively. Four cases (66.7%) required a cordocentesis for fetal transfusion, and two cases (33.3%) received blood transfusions immediately following delivery. Among the four multigravida cases, two (50%) noted previous pregnancies complicated by neonatal anemia. When reported, the maternal cases included two G6PD deficiency carrier patients and two G6PD-deficient patients. Exposures to substances known to cause G6PD deficiency-related hemolysis occurred in 3/6 (50%) cases. CONCLUSION: Six cases of NIHF/severe fetal anemia were associated with G6PD deficiency. While G6PD deficiency is an X-linked recessive condition, female fetuses can be affected. Fetal G6PD deficiency testing can be considered if parental history indicates, particularly if the standard workup for NIHF is negative.

Implementation of Universal Screening for G6PD Deficiency in Newborns.

We describe the implementation of universal glucose-6-phosphate dehydrogenase (G6PD) screening during the first year of New York State mandated testing, as well as operational challenges and clinical knowledge gained. All infants born at or transferred to our center between June 21, 2022 and June 30, 2023, underwent testing for G6PD enzyme deficiency and were included in the study cohort. Infant blood samples were collected and sent to a reference laboratory for quantitative assay. After initiation of universal screening, a quality improvement initiative was launched to: monitor and improve the suitability of blood sample collection to ensure timely return of results;improve the reliability and validity of the reference laboratory enzyme assay; andestablish accurate reference ranges for G6PD deficiency in newborns.A total of 5601 newborns were included. Within the first year of implementation, the percentage of samples yielding any test result increased from 76% to 85%, and most patients had a G6PD result available within 1 day of discharge. We established a more accurate threshold for G6PD deficiency in newborns of <4.9 U/g Hb and G6PD intermediate of <10.0 U/g Hb. Using the updated reference ranges, 224 patients in our cohort were identified as G6PD deficient or intermediate (4.0%). Through a quality-sensitive process, we identified the importance of a standardized approach, improved sample collection processes, decreased sample turnaround time, and established more accurate reference ranges. We hope our experiences will help others seeking to improve processes and implement similar programs at other institutions.

The global role of G6PD in infection and immunity.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzymopathy in humans. G6PD is an essential enzyme in the pentose phosphate pathway (PPP), generating NADPH needed for cellular biosynthesis and reactive oxygen species (ROS) homeostasis, the latter especially key in red blood cells (RBCs). Beyond the RBC, there is emerging evidence that G6PD exerts an immunologic role by virtue of its functions in leukocyte oxidative metabolism and anabolic synthesis necessary for immune effector function. We review these here, and consider the global immunometabolic role of G6PD activity and G6PD deficiency in modulating inflammation and immunopathology.

An Unexpected Finding of Klinefelter Syndrome during Glucose-6-Phosphate Dehydrogenase Deficiency (G6PD) Genetic Analysis.

BACKGROUND: Klinefelter syndrome is a common sex chromosome abnormality in males, characterized by an extra X chromosome compared to normal males. Glucose-6-phosphate dehydrogenase deficiency (G6PD) is an X-linked incomplete dominant defect disorder. In this study, we reported the unexpected detection of Klinefelter syndrome in a patient with G6PD. METHODS: G6PD enzyme activity was measured by immunoenzyme assay, and genetic analysis was performed using a fluorescent PCR melting curve method (PCR-melting curve). Sex chromosome number abnormalities were detected by multiplex ligation-dependent probe amplification (MLPA). The patient also underwent peripheral blood chromosome karyotype analysis. RESULTS: The patient's G6PD and 6PGD enzyme activities were 21.34 U/L and 22.85 U/L, respectively, and their ratio was below the reference range (0.93). The PCR-melting curve displayed a c.1388 heterozygous mutation in this boy, and the Sanger sequencing provided the same results. MLPA results suggested the presence of approxi-mately two copies of the X-chromosome in the boy. Finally, chromosome karyotype analysis confirmed that the boy had Klinefelter syndrome with a karyotype of 47, XXY. CONCLUSIONS: Klinefelter syndrome was accidentally detected during G6PD genetic analysis in a male. X-chromosomes can interfere with the results of G6PD genetic analysis and should be noted.

Risk of diabetes mellitus based on the interactive association between G6PD rs72554664 polymorphism and sex in Taiwan Biobank individuals.

The presence of glucose-6-phosphate dehydrogenase (G6PD) deficiency may increase the risk of type 2 diabetes mellitus (T2DM), with differing prevalence between males and females. Although G6PD deficiency is an X-linked genetic condition, its interaction with sex regarding T2DM risk among the Taiwanese population has not been fully explored. This study aimed to investigate the association between G6PD deficiency and T2DM risk in the Taiwanese population, focusing on the potential influence of sex. Data were obtained from the Taiwan Biobank (TWB) database, involving 85,334 participants aged 30 to 70 years. We used multiple logistic regression analysis to assess the interaction between G6PD rs72554664 and sex in relation to T2DM risk. The T2DM cohort comprised 55.35% females and 44.65% males (p < 0.001). The TC + TT genotype of rs72554664 was associated with an increased risk of T2DM, with an odds ratio (OR) of 1.95 (95% CI: 1.39-2.75), and males showed an OR of 1.31 (95% CI: 1.19-1.44). Notably, the G6PD rs72554664-T allelic variant in hemizygous males significantly elevated the T2DM risk (OR), 4.57; p < 0.001) compared to females with the CC genotype. Our findings suggest that the G6PD rs72554664 variant, in conjunction with sex, significantly affects T2DM risk, particularly increasing susceptibility in males. The association of the G6PD rs72554664-T allelic variant with a higher risk of T2DM highlights the importance of sex-specific mechanisms in the interplay between G6PD deficiency and T2DM.

Perspectives of healthcare professionals on training for quantitative G6PD testing during implementation of tafenoquine in Brazil (QualiTRuST Study).

Effective radical cure of Plasmodium vivax malaria is essential for malaria elimination in Brazil. P. vivax radical cure requires administration of a schizonticide, such as chloroquine, plus an 8-aminoquinoline. However, 8-aminoquinolines cause hemolysis in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency, requiring prior screening to exclude those at risk. Brazil is pioneering the implementation of tafenoquine, a single-dose 8-aminoquinoline indicated for P. vivax patients with >70% of normal G6PD activity. Tafenoquine implementation in Manaus and Porto Velho, two municipalities located in the western Brazilian Amazon, included comprehensive training of healthcare professionals (HCPs) on point-of-care quantitative G6PD testing and a new treatment algorithm for P. vivax radical cure incorporating tafenoquine. Training was initially provided to higher-level facilities (phase one) and later adapted for primary care units (phase two). This study analyzed HCP experiences during training and implementation and identified barriers and facilitators. In-depth interviews and focus discussion groups were conducted 30 days after each training for a purposive random sample of 115 HCPs. Thematic analysis was employed using MAXQDA software, analyzing data through inductive and deductive coding. Analysis showed that following the initial training for higher-level facilities, some HCPs did not feel confident performing quantitative G6PD testing and prescribing the tafenoquine regimen. Modifications to the training in phase two resulted in an improvement in understanding the implementation process of the G6PD test and tafenoquine, as well as in the knowledge acquired by HCPs. Additionally, knowledge gaps were addressed through in situ training, peer communication via a messaging app, and educational materials. Training supported effective deployment of the new tools in Manaus and Porto Velho and increased awareness of the need for pharmacovigilance. A training approach for nationwide implementation of these tools was devised. Implementing quantitative G6PD testing and tafenoquine represents a significant shift in P. vivax malaria case management. Consistent engagement with HCPs is needed to overcome challenges in fully integrating these tools within the Brazilian health system.

The PreQuine Platform: A novel diagnostic tool for measuring glucose-6-phosphate dehydrogenase (G6PD) activity and hemoglobin concentration.

Quantitative diagnosis of glucose-6-phosphate dehydrogenase (G6PD) deficiency is essential for the safe administration of 8-aminoquinoline based radical cure for the treatment of Plasmodium vivax infections. Here, we present the PreQuine Platform (IVDS, USA), a quantitative biosensor that uses a dual-analyte assay for the simultaneous measurement of Hemoglobin (Hgb) levels and G6PD enzyme activity within the same sample. The platform relies on a downloadable mobile application. The device requires 10µl of whole blood and works with a reflectance-based meter. Comparing the G6PD measurement normalized by Hgb of 12 samples from the PreQuine Platform with reference measurements methods (spectrophotometry, Pointe Scientific, USA and hemoglobin meter, HemoCue, Sweden) showed a positive and significant agreement with a slope of 1.0091 and an intercept of -0.0379 under laboratory conditions. Next steps will be to conduct field trials in Bangladesh, Cambodia, and the USA to assess diagnostic performance, user friendliness and acceptance.

Population pharmacokinetics of primaquine and its metabolites in African males.

BACKGROUND: Primaquine (PQ) is the prototype 8-aminoquinoline drug, a class which targets gametocytes and hypnozoites. The World Health Organization (WHO) recommends adding a single low dose of primaquine to the standard artemisinin-based combination therapy (ACT) in order to block malaria transmission in regions with low malaria transmission. However, the haemolytic toxicity is a major adverse outcome of primaquine in glucose-6-phosphate dehydrogenase (G6PD)-deficient subjects. This study aimed to characterize the pharmacokinetic properties of primaquine and its major metabolites in G6PD-deficient subjects. METHODS: A single low-dose of primaquine (0.4-0.5 mg/kg) was administered in twenty-eight African males. Venous and capillary plasma were sampled up to 24 h after the drug administration. Haemoglobin levels were observed up to 28 days after drug administration. Only PQ, carboxy-primaquine (CPQ), and primaquine carbamoyl-glucuronide (PQCG) were present in plasma samples and measured using liquid chromatography mass spectrometry. Drug and metabolites' pharmacokinetic properties were investigated using nonlinear mixed-effects modelling. RESULTS: Population pharmacokinetic properties of PQ, CPQ, and PQCG can be described by one-compartment disposition kinetics with a transit-absorption model. Body weight was implemented as an allometric function on the clearance and volume parameters for all compounds. None of the covariates significantly affected the pharmacokinetic parameters. No significant correlations were detected between the exposures of the measured compounds and the change in haemoglobin or methaemoglobin levels. There was no significant haemoglobin drop in the G6PD-deficient patients after administration of a single low dose of PQ. CONCLUSIONS: A single low-dose of PQ was haematologically safe in this population of G6PD-normal and G6PD-deficient African males without malaria. Trial registration NCT02535767.

Kinetics of glucose-6-phosphate dehydrogenase (G6PD) activity during Plasmodium vivax infection: implications for early radical malaria treatment.

BACKGROUND: Plasmodium vivax relapses due to dormant liver hypnozoites can be prevented with primaquine. However, the dose must be adjusted in individuals with glucose-6-phosphate-dehydrogenase (G6PD) deficiency. In French Guiana, assessment of G6PD activity is typically delayed until day (D)14 to avoid the risk if misclassification. This study assessed the kinetics of G6PD activity throughout P. vivax infection to inform the timing of treatment. METHODS: For this retrospective monocentric study, data on G6PD activity between D1 and D28 after treatment initiation with chloroquine or artemisinin-based combination therapy were collected for patients followed at Cayenne Hospital, French Guiana, between January 2018 and December 2020. Patients were divided into three groups based on the number of available G6PD activity assessments: (i) at least two measurements during the P. vivax malaria infection; (ii) two measurements: one during the current infection and one previously; (iii) only one measurement during the malaria infection. RESULTS: In total, 210 patients were included (80, 20 and 110 in groups 1, 2 and 3, respectively). Data from group 1 showed that G6PD activity remained stable in each patient over time (D1, D3, D7, D14, D21, D28). None of the patients with normal G6PD activity during the initial phase (D1-D3) of the malaria episode (n = 44) was categorized as G6PD-deficient at D14. Patients with G6PD activity < 80% at D1 or D3 showed normal activity at D14. Sex and reticulocyte count were statistically associated with G6PD activity variation. In the whole sample (n = 210), no patient had severe G6PD deficiency (< 10%) and only three between 10 and 30%, giving a G6PD deficiency prevalence of 1.4%. Among the 100 patients from group 1 and 2, 30 patients (26.5%) were lost to follow-up before primaquine initiation. CONCLUSIONS: In patients treated for P. vivax infection, G6PD activity did not vary over time. Therefore, G6PD activity on D1 instead of D14 could be used for primaquine dose-adjustment. This could allow earlier radical treatment with primaquine, that could have a public health impact by decreasing early recurrences and patients lost to follow-up before primaquine initiation. This hypothesis needs to be confirmed in larger prospective studies.