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Glucose-6-Phosphate Dehydrogenase Deficiency

Title

Ñ    Glucose-6-Phosphate Dehydrogenase Deficiency (G6PD deficiency)

Definition

Ñ    Inherited enzyme deficiency that presents as a haemolytic anaemia

Aetiology

Ñ    X-linked recessive:

Mainly affects males

Ñ    Females may have clinical problems due to lysonisation:

Random X-chromosome inactivation resulting in two populations of red cells; one normal, one G-6-PD deficient

Pathogenesis

Clinical syndromes are caused by:

Ñ    Drugs:

·          Antimalarials:

Chloroquine, primaquine, pyrimethamine, quinine, pamaquine

·          Antibacterials:

Sulphonamides, nitrofurantoin, nitrofurazone, furazolidone, chloramphenicol, ciprofloxacin, dapsone

·          Analgesics:

Aspirin

·          Others:

Vitamin K, probenecid, quinidine, dimercaprol

Ñ    Infections

Ñ    Acute illnesses

Ñ    Favism:

Ingestion of fava beans

Pathological Process

Ñ    G6PD is the only source of NADPH in red cells

Ñ    NADPH is utilised via glutathione to protect red cells from oxidative damage

Ñ    Hence G6PD deficiency results in damage to red cells when they are exposed to oxidative stress

Clinical Features

History

G6PD deficiency may result in:

Ñ    Acute drug induced haemolysis

Ñ    Haemolysis induced by infections and acute illnesses

Ñ    Chronic haemolytic anaemia

Ñ    Neonatal jaundice

Examination

KUS

Ñ    Haemoglobinuria

HS

Ñ    Anaemia

IS

Ñ    Jaundice

Investigations

Fluids

Blood

Haematology

Ñ    Anaemia

Ñ    Reticulocytosis

Blood film:

Ñ    Irregularly contracted cells

Ñ    Bite cells:

Cells with indentation of the cell membrane

Ñ    Blister cells:

Cells in which the haemoglobin is retracted from the cell membrane

Ñ    Heinz bodies:

Denatured haemoglobin

Seen as inclusions within the red cell

They are removed by the spleen resulting in bite cells

Biochemistry

Ñ    Bilirubin:

Increased

Ñ    Plasma haptoglobin:

Reduced

Ñ    Methhaemalbuminaemia:

Schumm’s test

Ñ    Serum lactate dehydrogenase:

Raised

Ñ    G6PD Deficiency:

Demonstrate decreased ability to reduce dyes

Direct assay of enzyme levels

Genetics

Ñ    DNA analysis

Urine

Ñ    Urinary urobilinogen:

Increased

Ñ    Haemosiderinuria

Management

Control

Drugs

Ñ    Discontinue offending drugs

Ñ    Treat any underlying infections

Support

Ñ    Blood transfusion

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