G6PD deficiency is a condition where there is a defect in the G6PD enzyme normally found in all cells in the body.
It is more common in Mediterranean, Middle Eastern and African patients. It is inherited in an X linked recessive pattern, meaning it usually affects males, as they have only a single copy of the gene on their single X chromosome. It causes crises that are triggered by infections, medications or fava beans (broad beans).
TOM TIP: The key piece of knowledge for G6PD deficiency relates to triggers. In your exam look out for a patient that becomes jaundice and anaemic after eating broad beans, developing an infection or being treated with antimalarial medications. The underlying diagnosis might be G6PD deficiency.
Pathophysiology
The G6PD enzyme is responsible for helping protect cells from damage by reactive oxygen species (ROS). ROS are reactive molecules that contain oxygen, produced during normal cell metabolism and in higher quantities during stress on the cell. The G6PD enzyme is particularly important in red blood cells. A deficiency in G6PD makes cells more vulnerable to ROS, leading to haemolysis in red blood cells. Periods of increased stress, with a higher production of ROS, can lead to acute haemolytic anaemia.
Presentation
G6PD often presents with neonatal jaundice.
Other features of the condition are:
- Anaemia
- Intermittent jaundice, particularly in response to triggers
- Gallstones
- Splenomegaly
Heinz bodies may be seen on a on blood film. Heinz bodies are blobs of denatured haemoglobin (“inclusions”) seen within the red blood cells.
Diagnosis can be made by doing a G6PD enzyme assay.
Management
Patient should avoid triggers to acute haemolysis where possible. This includes avoiding fava beans and certain medications.
Medications that trigger haemolysis and should be avoided include:
- Primaquine (an antimalarial)
- Ciprofloxacin
- Nitrofurantoin
- Trimethoprim
- Sulfonylureas (e.g gliclazide)
- Sulfasalazine and other sulphonamide drugs
Last updated January 2020