THE CLINICAL PICTURE OF GLUCOSE 6-PHOSPHATE DEHYDROGENASE DEFICIENCY IN EARLY INFANCY

Management of severe hyperbilirubinemia in the cholestatic neonate: a review and an approach

A review of the literature demonstrates that severe total hyperbilirubinemia (total serum bilirubin ≥ 20 mg/dL [340 µmol/L]) in some cholestatic term (≥37 weeks) and late-preterm (≥34^0/7-36^6/7 weeks) gestation neonates poses a risk for bilirubin-induced brain damage. When the direct bilirubin fraction is <50% of the total serum bilirubin this risk is associated with the total serum bilirubin alone and treatment decisions should be based on the total serum bilirubin. On the other hand, there are limited data on the risk of bilirubin-induced brain damage in the neonate with severe total hyperbilirubinemia and a direct bilirubin fraction that is equal to or exceeds 50% of the total serum bilirubin. When this rare combination occurs, efforts to keep the indirect bilirubin fraction from reaching severe levels might, nevertheless, be prudent.

G6PD deficiency: global distribution, genetic variants and primaquine therapy

Glucose-6-phosphate dehydrogenase (G6PD) is a potentially pathogenic inherited enzyme abnormality and, similar to other human red blood cell polymorphisms, is particularly prevalent in historically malaria endemic countries. The spatial extent of Plasmodium vivax malaria overlaps widely with that of G6PD deficiency; unfortunately the only drug licensed for the radical cure and relapse prevention of P. vivax, primaquine, can trigger severe haemolytic anaemia in G6PD deficient individuals. This chapter reviews the past and current data on this unique pharmacogenetic association, which is becoming increasingly important as several nations now consider strategies to eliminate malaria transmission rather than control its clinical burden. G6PD deficiency is a highly variable disorder, in terms of spatial heterogeneity in prevalence and molecular variants, as well as its interactions with P. vivax and primaquine. Consideration of factors including aspects of basic physiology, diagnosis, and clinical triggers of primaquine-induced haemolysis is required to assess the risks and benefits of applying primaquine in various geographic and demographic settings. Given that haemolytically toxic antirelapse drugs will likely be the only therapeutic options for the coming decade, it is clear that we need to understand in depth G6PD deficiency and primaquine-induced haemolysis to determine safe and effective therapeutic strategies to overcome this hurdle and achieve malaria elimination.

An update on the prevalence of glucose-6-phosphate dehydrogenase deficiency and neonatal jaundice in Tehran neonates

OBJECTIVES

The aim of this study was to screen newborns in Tehran for glucose-6-phosphate dehydrogenase (G6PD) deficiency in relation to hyperbilirubinemia and jaundice.

DESIGN AND METHODS

We performed quantitative and qualitative red blood cell (RBC) G6PD assays in cord blood of 2000 male and female at-term neonates. Observations for jaundice and bilirubin determination were made in G6PD-deficient and normal groups. Those with severe jaundice were treated with phototherapy or exchange transfusion.

RESULTS

Our results showed that 2.1% (3.6% of males and 0.6% of females) was G6PD-deficient. Those with severe jaundice and hyperbilirubinemia (160 normal and 17 G6PD-deficient) were hospitalized and treated with phototherapy or exchange transfusion. Bilirubin levels in G6PD-deficient neonates were somewhat higher compared to G6PD-normal babies (18.8 +/- 2.4 mg/dl [321.5 +/- 41 micromol/l] vs. 15.7 +/- 3.2 mg/dl [268.5 +/- 54.7 micromol/l]; P < 0.05). G6PD activity was significantly lower in G6PD-deficient group than in the normal group (2.1 +/- 0.7 vs. 12.5 +/- 5.0 U/g Hb; P < 0.001).

CONCLUSION

This study shows that the incidence of G6PD deficiency in newborns of Tehran is 2.1%, which is relatively high, and also hyperbilirubinemia and jaundice are approximately 3-fold higher in G6PD-deficient group than in the G6PD-normal group (51% vs. 16%). This emphasizes the necessity of neonatal screening on cord blood samples of both sexes for G6PD deficiency and the need to watch closely for development of hyperbilirubinemia.

A single dose of Sn-mesoporphyrin prevents development of severe hyperbilirubinemia in glucose-6-phosphate dehydrogenase-deficient newborns

OBJECTIVES

Severe neonatal jaundice is a common clinical manifestation of glucose-6-phosphate dehydrogenase (G-6-PD) deficiency and the most difficult to manage; kernicterus is not an uncommon outcome. We assessed in healthy, direct Coombs test-negative Greek newborns of >/=38 weeks' gestational age 1) the current burden of G-6-PD deficiency-associated severe jaundice, and 2) the efficacy of preventive use of Sn-mesoporphyrin (SnMP), a potent inhibitor of heme oxygenase activity and thus of bilirubin production, in ameliorating jaundice in G-6-PD-deficient neonates.

METHODS

The studies were conducted at Metera Maternity Hospital in Athens, Greece. Enrolled newborns had the plasma bilirubin concentration (PBC) determined in cord blood and daily thereafter until a declining level was obtained and the case was closed. Intervention with phototherapy was dictated at exact, age-specific PBC levels. In our initial study, we enrolled consecutive mature healthy G-6-PD-deficient newborns as well as a threefold excess of G-6-PD-normal neonates born at approximately the same time (control group). For the SnMP trial, G-6-PD-deficient neonates were administered SnMP as a single intramuscular dose of 6 micromol/kg birth weight within 24 +/- 12 hours of age.

RESULTS

SnMP was administered at 26.7 +/- 6.1 hours of age to 172 G-6-PD-deficient newborns (group A); 168 G-6-PD-normal (group B) and 58 G-6-PD-deficient (group C) newborns who were enrolled earlier provided the comparison groups. Except for the expected excess of males in the G-6-PD-deficient groups (A and C), there were no differences in the demographic characteristics among the 3 groups. The incremental changes in PBC from cord blood to 24 hours of age also were similar (group A: 4.13 +/- 1.32 mg/dL; group B: 4.05 +/- 1.34 mg/dL; group C: 4.39 +/- 1.07 mg/dL), but there were significant differences in the next period, 24 to 48 hours of age (group A: 0.63 +/- 1.44 mg/dL; group B: 1.69 +/- 1.5 mg/dL; group C: 2.45 +/- 1.72 mg/dL). Peak PBC was significantly different (group A: 7.81 +/- 3.04 mg/dL; group B: 8.68 +/- 3.1 mg/dL; group C: 11.24 +/- 3.76 mg/dL) as was the age at which peak PBC was recorded (group A: 56 +/- 29 hours of age; group B: 69 +/- 26 hours of age; group C: 83 +/- 29 hours of age). These differences in favor of group A were observed despite the fact that phototherapy was used in 15% of the newborns in group B and 31% of those in group C, whereas none of those treated with SnMP required phototherapy. Finally, in one female, who was heterozygous for G-6-PD deficiency, in group C phototherapy failed and 2 exchange transfusions were performed.

CONCLUSIONS

In comparison with normal neonates, G-6-PD-deficient neonates experienced a twofold increase in the prevalence of significant hyperbilirubinemia requiring phototherapy. A single dose of SnMP administered in the 1st day of life to the G-6-PD-deficient newborns shifted the peak PBC distribution to the left (lower values) even in relation to normal neonates and entirely eliminated the need for phototherapy. Interdiction of bilirubin production by use of a heme oxygenase inhibitor such as SnMP represents a simple and highly effective means for the preventive management of jaundice in G-6-PD-deficient newborns.

Effect of vitamin K1 on glucose-6-phosphate dehydrogenase deficient neonatal erythrocytes in vitro

AIM

To determine whether vitamin K1, which is routinely administered to neonates, could act as an exogenous oxidising agent and be partly responsible for haemolysis in glucose-6-phosphat-dehydrogenase (G-6-PD).

METHODS

G-6-PD deficient (n = 7) and control (n = 10) umbilical cord blood red blood cells were incubated in vitro with a vitamin K1 preparation (Konakion). Two concentrations of Vitamin K1 were used, both higher than that of expected serum concentrations, following routine injection of 1 mg vitamin K1. Concentrations of reduced glutathione (GSH) and methaemoglobin, indicators of oxidative red blood cell damage, were determined before and after incubation, and the mean percentage change from baseline calculated.

RESULTS

Values (mean (SD)) for GSH, at baseline, and after incubation with vitamin K1 at concentrations of 44 and 444 microM, respectively, and percentage change from baseline (mean (SD)) were 1.97 + 0.31 mumol/g haemoglobin, 1.89 +/- 0.44 mumol/g (-4.3 +/- 13.1%), and 1.69 +/- 0.41 mumol/g (-14.5 +/- 9.3%) for the G-6-PD deficient red blood cells, and 2.27 +/- 0.31 mumol/g haemoglobin, 2.09 +/- 0.56 mumol/g (-7.2 +/- 23.2%), and 2.12 +/- 0.38 mumol/g (-6.0 + 14.1%) for the control cells. For methaemoglobin (percentage of total haemoglobin), the corresponding values were 2.01 +/- 0.53%, 1.93 +/- 0.37% (-0.6 +/- 17.4%) and 2.06 +/- 0.43% (5.7 +/- 14.2%) for the G-6-PD deficient red blood cells, and 1.56 +/- 0.74%, 1.70 +/- 0.78% (12.7 +/- 21.9%), and 1.78 +/- 0.71% (20.6 +/- 26.8%) for the control red blood cells. None of the corresponding percentage changes from baseline was significantly different when G-6-PD deficient and control red blood cells were compared.

CONCLUSIONS

These findings suggest that G-6-PD deficient red blood cells are not at increased risk of oxidative damage from vitamin K1.

Control of hyperbilirubinemia in glucose-6-phosphate dehydrogenase-deficient newborns using an inhibitor of bilirubin production, Sn-mesoporphyrin

BACKGROUND

Hyperbilirubinemia in new-borns with glucose-6-phosphate dehydrogenase (G6PD) deficiency is a serious clinical problem because of the severity and unpredictability of its course. An innovative approach to this problem is suggested by previous experience with Sn-mesoporphyrin (SnMP), a potent inhibitor of bilirubin production, in moderating neonatal hyperbilirubinemia caused by ABO incompatibility, immaturity, and unspecified mechanisms.

OBJECTIVE

To compare the effectiveness of the preventive and therapeutic uses of SnMP in ameliorating the course of bilirubinemia of G6PD-deficient neonates.

METHODS

Neonates born at the Metera Maternity Hospital, Athens, Greece, and found to be G6PD-deficient by cord blood testing were stratified by sex and gestational age (210-265 days and >265 days) and randomized in pairs to receive SnMP (6 micromol/kg birth weight, intramuscularly) either on the first day of life (preventive use) or if and when the plasma bilirubin concentration (PBC) level reached an age-specific threshold level for intervention (therapeutic use). In the case of failure of SnMP to control the rise of PBC levels, the protocol defined precisely the threshold PBC levels for switchover to phototherapy (PT) and, if necessary, exchange transfusion. PBC was measured daily until a declining value was obtained and the case was closed.

RESULTS

A total of 86 G6PD-deficient neonates were randomized: 42 in the preventive arm and 44 in the therapeutic arm. Of the latter, 20 (45%) reached PBC levels requiring therapeutic intervention and thus received SnMP. Regardless of the trial arm, none of the 86 neonates required PT, whereas in a previous study in the same population, 33% of G6PD-deficient neonates required PT. In the intrapair sequential analysis, the favored arm was decided on the criterion of the age at closure of the case being shorter by at least 1 day. After plotting 30 untied pairs in the sequential analysis graph, the preventive use of SnMP proved to be the favored arm, and the trial was stopped. At this point, there were 2 unpaired neonates, 12 tied pairs, 22 pairs in which the preventive use of SnMP was favored and 8 pairs in which the therapeutic use of SnMP was favored. In the group analysis, infants in the preventive group, compared with those in the therapeutic group, had a lower maximum PBC level (8.2 +/- 3.1 and 10.9 +/- 2.8 mg/dL, respectively), which was reached at an earlier age (63.5 +/- 34.8 and 82.2 +/- 24.7 hours, respectively) as well as a lower closing PBC level (7.2 +/- 2.9 and 9.6 +/- 2.5 mg/dL, respectively) and an earlier age at closing (89.1 +/- 35.6 and 110.8 +/- 23.6 hours, respectively). Moreover, a PBC level of >/=8.0 mg/dL, a level at which jaundice is clearly visible, was not reached by 52% of the neonates in the preventive arm and 16% of the neonates in the therapeutic arm.

CONCLUSIONS

In G6PD-deficient neonates, a single dose of SnMP administered preventively or therapeutically entirely supplanted the need for PT to control hyperbilirubinemia. The preventive use of SnMP offers practical advantages in populations with a high enough prevalence of G6PD deficiency to justify cord blood screening.

Neonatal screening for glucose-6-phosphate dehydrogenase deficiency: sex distribution

Eight hundred and six newborn infants at high risk for glucose-6-phosphate dehydrogenase (G-6-PD) deficiency were screened; 30.2% of the boys and 10.4% of the girls had severe G-6-PD deficiency. Surprisingly, 14% of the enzyme deficient girls had a father from a low risk ethnic group. Girls of high risk mothers should be screened for G-6-PD deficiency regardless of paternal origin.

Severe neonatal jaundice associated with glucose-6-phosphate dehydrogenase deficiency: pathogenesis and global epidemiology

The association of glucose-6-phosphate dehydrogenase deficiency (G6PD def) with severe neonatal jaundice (NJ) and Kernicterus was described just over 30 years ago in reports from Sardinia (1-4) Singapore (5,6) and Greece (7,8). In this review we will examine the progress made since that time in our understanding of the pathophysiology of severe NJ associated with G6PD def, its global epidemiology, and its role in the balanced polymorphism of the G6PD def gene (Gd). Including this review in the Festschrift to Spyros Doxiadis should highlight his contribution to the field. In Greece the search for a new cause of severe NJ and Kernicterus was triggered by his realization that the recognized at the time, causes of severe NJ were absent in a large proportion of the neonates treated at the "Alexandra" Maternity Hospital in Athens (9).

Neonatal jaundice and severity of glucose-6-phosphate dehydrogenase deficiency in Sardinian babies

We have investigated the association of neonatal jaundice (NNJ) and G6PD deficiency in consecutive births in a Northern Sardinian hospital. After excluding known causes for NNJ, and after correcting for the incidence of NNJ from unknown causes, we estimated that 20% of G6PD deficient male newborns develop NNJ resulting from their enzyme deficiency. By analyzing in detail 100 G6PD deficient babies we found no differences in birth weight or haemoglobin level between those without and those with NNJ, four of whom required exchange transfusion. We further showed by an accurate quantitative method that the residual G6PD enzyme activity was not significantly lower in G6PD deficient babies with NNJ compared to G6PD deficient babies without NNJ.

Glucose-6-phosphate dehydrogenase deficiency in Sicily. Incidence, biochemical characteristics and clinical implications

This report deals with the incidence, type and clinical implications of G6PD deficiency in Sicily. Of 3347 male subjects examined, 56 were deficient in G6PD. They were distributed throughout the island. The G6PD levels in RBC were almost zero; in leukocytes, platelets and saliva they were found to be 26%, 18% and 16%, respectively, of controls. The Michaelis constant for NADP and G6PD was lower than for controls. Conversely, the utilization of the analogous Ga16P and 2dG6P was higher. The thermostability of the enzyme was lower and the pH optima (6.5 and 9.5) were different from the controls. An identical electrophoretic pattern was found both in normal and deficient subjects. This pattern is superimposable on that described as Mediterranean variant. The analysis among 270 subjects admitted to our Clinic with hemolysis due to G6PD deficiency demonstrated that the most frequent disease is favism, followed by neonatal jaundice, while hemolysis due to drugs is very rare. Ingestion of fresh fava beans was the most frequent cause of favism, but cases occurred after breast feeding and inhalation of pollen.

The role of haemolysis in neonatal hyperbilirubinaemia as reflected in carboxyhaemoglobin levels

Carboxyhaemoglobin levels were measured in 250 consecutive, normal, term newborns and in a group of 75 severely jaundiced infants in an effort to assess the role of haemolysis in non-specific neonatal hyperbilirubinaemia--"Physiologic jaundice"-as well as in severe jaundice of various etiologies. In normal newborns a significant correlation (r=0.3293, p less than 0.001) was found between third-day carboxyhaemoglobin and serum bilirubin levels. Significant correlations were also found between the cord and third day values for carboxyhaemoglobin (infants of non-smoking mothers) for reticulocyte count, and for serum bilirubin. Third day haemoglobin showed no correlation with any of the other parameters including cord haemoglobin. Of the infants with third day carboxyhaemoglobin up to 0.75%, 1.7% had third day serum bilirubin values above 16.0 mg/100 ml. The corresponding percentage for the infants with carboxyhaemoglobin above 0.75% was 6.1%. It is concluded that increased rates of haemolysis due to as yet unspecified caused play an important role in the non-specific hyperbilirubinaemia of normal term newborns. As expected, high levels of carboxyhaemoglobin were found in infants with severe jaundice due to Rhesus and ABO haemolytic disease and glucose-6-phosphate dehydrogenase deficiency but also in jaundiced prematures and in Greek infants with severe jaundice of unknown cause.

Neonatal jaundice and glucose-6-phosphate dehydrogenase deficiency in Papua New Guinea

Of 50 jaundiced neonatal patients studied at the Port Moresby General Hospital, 11 (22%) were found to be glucose-6-phosphate dehydrogenase-deficient. No apparent exogenous precipitating causes for the jaundice were noted. Serum bilirubin levels exceeded 20 mg/100 ml in seven of these glucose-6-phosphate dehydrogenase-deficient infants, and exchange transfusions were required for three subjects. Glucose-6-phosphate dehydrogenase deficiency must be considered in the differential diagnosis of neonatal jaundice in Papua New Guinea.

Clinical evaluation of Sephadex gel filtration in estimation of bilirubin binding in serum in neonatal jaundice

Clinical experience with a Sephadex gel filtration test-kit for the evaluation of bilirubin binding affinity of serum in neonatal jaundice is reported. In serial serum specimens from 166 jaundiced neonates the results of the test in most cases were in accord with the independent clinical decision to perform exchange transfusion. In all 9 cases with clinical kernicterus the Sephadex test was strongly positive (very low bilirubin binding affinity of serum). The test was positive at lower bilirubin levels and bilirubin/albumin molar ratios in preterm as compared with term neonates, especially in those in poor clinical condition. Among term infants the test indicated an increase in bilirubin binding affinity after the 5th day of life.

Diagnostic problems in severe neonatal jaundice and G6PD deficiency in Greece

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