European Journal of Cardiovascular Medicine

Glucose – 6 Phosphate Dehydrogenase deficiency is the most common erythrocyte enzymopathy, being present in more than 400 million people worldwide which presents in the neonatal period as unconjugated hyperbilirubinemia and is inherited as an X- linked recessive disorder.¹ G6PD deficiency was first reported in India as early as 1961. The exact incidence in India is not known, however several studies has reported incidence as high as 0 – 27.9 % ^2. There is no established routine newborn screening protocol established in major parts of the country.

G6PD is a cytoplasmic enzyme in the   hexose monophosphate  pathway and catalyzes the conversion of nicotinamide adenine dinucleotide phosphate (NADP) to its reduced form, NADPH. NADPH maintains glutathione in its reduced form, which acts as a scavenger for dangerous oxidative metabolites. G6PD also protects red blood cells from potentially harmful by-products that can accumulate when a person takes certain medications or when the body is fighting an infection that would otherwise cause precipitation of haemoglobin (Heinz bodies) or damage the RBC membrane.  The prevalence of neonatal hyperbilirubinemia is twice that of the general population in males who carry the defective gene and in homozygous females³. It rarely occurs in heterozygous females.^3,4. Infants with the severe variant of G6PD deficiency may develop severe hyperbilirubinemia to cause kernicterus^5,6 .

The diagnosis of red cell enzyme deficiency usually depends on the demonstration of decreased enzyme activity either through a quantitative assay or a screening test. There are several methods available for the diagnosis of G6PD deficiency. However, fluorescent spot test and dichlorophenol indophenol (DPIP) decolorization method were found to be useful and suitable for routine use. Therefore, the present study was conducted with the following aims and objectives of (1) Estimate the prevalence of Glucose-6-Phosphate Dehydrogenase deficiency in neonatal hyperbilirubinemia. (2) Ascertain different causes of neonatal hyperbilirubinemia in our institution requiring therapeutic interventions.

Study Type: Hospital based observational study.

 Study Period : From December 2022 to November 2023.

 Study Location: Neonatal Intensive Care Unit (NICU), Gauhati Medical College Hospital, Assam , India.

Study Population: Neonates admitted in NICU with hyperbilirubinemia during the study period.

Sample Size: To include neonates with hyperbilirubinemia as per inclusion and exclusion criteria. In this study sample size was 320.

Ethical clearance: The study was approved by the institutional ethics committee of  Gauhati Medical College and Hospital, Guwahati, Assam,

Consent: An informed consent was obtained from the parents of the neonates after explaining in detail about the procedure of the study in their vernacular language.

Inclusion criteria:

• Term neonates > 37 weeks of gestation
• Birth weight > 2500 grams
• Serum bilirubin > 12mg / dl

Exclusion criteria:

• Preterm, IUGR, SGA neonates
• Conjugated hyperbilirubinemia
• Congenital anomalies and Sick babies

Table 1: Sex wise distribution of neonate (n=320)

In this study, out of 320 jaundiced neonates, 198(61.9%) were males and 122(38.1%) were females [Table-1]

Table 2: Different causes of neonatal hyperbilirubinemia in the study population (n=320)

Physiological jaundice was the most common cause of neonatal hyperbilirubinemia (59.6%) followed by ABO incompatibility (22.5%).  G6PD deficiency was found to be 5.6 % in this study. [Table-2]   

Table 3. Distribution according to degree of severity of G6PD deficiency (n=18)

G6PD deficiency was found to be of mild degree in 38.9 % of cases , moderate in 61.1 % of cases whereas no cases was found to be having severe degree of G6PD deficiency.[Table-3]

Table 4: Level of bilirubin in different causes of pathological jaundice

 In the present study, total serum bilirubin level of the G6PD deficient cases was significantly higher at presentation than blood group incompatibility group or other causes of pathological jaundice [Table-4].

Table 5. Clinical and laboratory findings in G6PD deficient (n=18) versus G6PD normal cases (n=302).

In this study, it was observed that majority of G6PD deficient neonates were male 88.9% cases. The mean serum bilirubin in G6PD deficient group was 21.06 mg/dl and 18.2 mg/dl in the G6PD normal group. [Table-5].

Table 6:  Requirement of Exchange Transfusion or Phototherapy in the study population

This Table shows that 28% neonates required exchange transfusion in G6PD deficient group and 72% needed phototherapy only [Table-6].

Glucose-6-phosphate dehydrogenase deficiency, a hereditary predisposition to hemolysis, is the most common of all clinically significant enzyme defects in the whole of human biology. It is estimated to affect approximately 400 million people worldwide¹ with the highest prevalence rates in tropical Africa, the Middle East, tropical and subtropical Asia, some parts of the Mediterranean and in Papua, New Guinea. Several countries in Europe, South East Asia, the Middle East and the United States of America have successfully established a neonatal screening programme for this disorder. With almost 24 million children born annually in India, it is estimated that at least 390,000 children suffering from this disorder are born in India every year ⁸. Several agents have been identified as triggers for haemolysis, viral and bacterial infections being the most common. Certain drugs and chemicals have been implicated as haemolytic triggers. Hemolysis may also be triggered by ingestion of fava beans (Vicia faba) or even inhalation⁷ of its pollen. Early detection and prevention of haemolytic episodes (by avoiding the triggers) is possible in this disorder. Hence, a neonatal screening programme for G6PD deficiency in India is warranted with the increased availability of funds for the health sector.  One of the common risk factors for pathologic hyperbilirubinemia in newborns is deficiency of G6PD enzyme. Deficiency of this enzyme is the most prevalent enzymopathy in red blood cells that causes haemolysis and hyperbilirubinemia⁷.

Hyperbilirubinemia can be very severe in G6PD deficiency and induces permanent damage to the brain causing  kernicterus and death⁸. Overproduction of unconjugated bilirubin and lack of proper management of hyperbilirubinemia cause changes in the mitochondria of the basal ganglia and leads to impaired mitochondrial respiration, and also induce apoptosis, and cause bilirubin encephalopathy¹⁰. The pathogenesis of hyperbilirubinemia in deficient newborn babies is different from that in G6PD-normal ones¹¹. Meanwhile haemolysis is considered to be a principal cause of bilirubinemia in G6PD-normal neonates; but diminished bilirubin conjugation may be the main cause of hyperbilirubinemia in G6PD deficient newborn infants¹¹ . Although there is a natural immaturity of bilirubin conjugation in neonates, the bilirubin conjugation ability of G6PD deficient neonates who are also hyperbilirubinemia is even less efficient. Bilirubin conjugation ability in G6PD-deficient neonates may become worse due to increased haemolysis and more bilirubin production¹².

In the present study, out of total 320 studied neonates with hyperbilirubinemia, 198 (61.9%) were males and 122 (38%) were females which is similar to the study done by Isaac I et al who reported  65.3%  male children in their study ¹³.  In this study, the overall prevalence of G6PD deficiency was 5.6% compared to earlier study conducted in Nepal by Gautam N et al who reported 11% cases of G6PD deficiency¹⁶. Similarly, a study conducted in  India by Kumar P et al, in China by Fu C et al and in Iran by Moosazadeh M et al showed an overall burden of 8.5%, 7.28% and 6.7 % respectively^17-19. Kuruvilla K A et al observed in their study a higher incidence of G6PD deficiency were seen in the North and the West (15% in Parsees to 27% Angami Nagas) as compared to South India (1% to 2%) except in tribals of Tamil Nadu and Andhra Pradesh (5% to 13%) ²⁰.

WHO recommends population screening in regions where the prevalence of G6PD deficiency is 3–5% or more, but this has yet to become routine practice in many parts of India. The barriers to screening include cost, underestimation of the public health impact of G6PD deficiency by the medical community, lack of awareness of G6PD deficiency among people and paucity of guidelines regarding which high risk group should be preferentially screened when general population screening is not available. It is well known that hemoglobinopathies are common among people of Assam. Hence screening for G6PD deficiency in neonatal jaundice may be adopted as a non-mandatory screening test in Assam, especially in case of severe neonatal hyperbilirubinemia. Further, diagnosis of G6PD deficiency status also helps in prevention of future hemolysis due to exposure to offending agents.