Introduction

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the commonest red blood cell enzyme defect. It is more common in people from the Mediterranean and Africa and is inherited in an X-linked recessive fashion. Many drugs can precipitate a crisis as well as infections and broad (fava) beans

Epidemiology

  • Incidence: 5.00 cases per 100,000 person-years
  • Most commonly see in infants
  • Sex ratio: 1:1
Condition Relative
incidence
Glucose-6-phosphate dehydrogenase deficiency1
Hereditary spherocytosis0.10
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+

Pathophysiology

Pathophysiology
  • ↓ G6PD → ↓ glutathione → increased red cell susceptibility to oxidative stress

Clinical features

Features
  • neonatal jaundice is often seen
  • intravascular haemolysis
  • gallstones are common
  • splenomegaly may be present

Investigations

Blood film
  • Heinz bodies
  • Bite and blister cells may also be seen

Diagnosis is made by using a G6PD enzyme assay

Differential diagnosis

Comparing G6PD deficiency to hereditary spherocytosis:

Comparison of G6PD deficiency to hereditary spherocytosis

G6PD deficiencyHereditary spherocytosis
GenderMale (X-linked recessive)Male + female (autosomal dominant)
EthnicityAfrican + Mediterranean descentNorthern European descent
Typical history• Neonatal jaundice
• Infection/drugs precipitate haemolysis
• Gallstones
• Neonatal jaundice
• Chronic symptoms although haemolytic crises may be precipitated by infection
• Gallstones
• Splenomegaly is common
Blood filmHeinz bodiesSpherocytes (round, lack of central pallor)
Diagnostic testMeasure enzyme activity of G6PDOsmotic fragility test

Management

Some drugs causing haemolysis
  • anti-malarials: primaquine
  • ciprofloxacin
  • sulph- group drugs: sulphonamides, sulphasalazine, sulfonylureas

Some drugs thought to be safe
  • penicillins
  • cephalosporins
  • macrolides
  • tetracyclines
  • trimethoprim