Anaemia - Glucose-6-Phosphate Dehydrogenase Deficiency Flashcards
Outline the epidemiology of Glucose-6-Phosphate Dehydrogenase Deficiency anaemia (4).
- It is one of the most common enzyme deficiency states in the world, and one of the most frequent inherited disorders.
- More than 400 million people are affected worldwide.
- The highest prevalence is in people of African, Mediterranean, and Asian heritage. The prevalence in Kurdish Jews is 50%-70%.
- As with all sex-linked conditions, the prevalence among females is higher but they are generally asymptomatic
What are the risk factors of Glucose-6-Phosphate Dehydrogenase Deficiency anaemia (4 / Hx 2)?
- Male sex
- Neonate
- Ethnic origin in the Mediterranean, sub-Saharan Africa, Middle East, or Southeast Asia
- Fx
Hx:
* Recent exposure to oxidative drugs
infection
* Recent exposure to broad beans (favism)
Outline the pathogenesis of Glucose-6-Phosphate Dehydrogenase Deficiency anaemia.
Heterozygous females are genetic mosaics: half of their cells are normal; the other half are completely deficient in G6PD.
Outline the pathophysiology of Glucose-6-Phosphate Dehydrogenase Deficiency anaemia (5).
- G6PD is required by all cells to protect them from damage by oxidation
- It catalyses the first step in the pentose phosphate pathway, whereby glucose-6-phosphate is oxidised to 6-phosphogluconate
- This reaction is linked to the reduction of NADP (nicotinamide adenine dinucleotide phosphate) to NADPH (reduced nicotinamide adenine dinucleotide phosphate), which is used to generate reduced glutathione
- Red blood cells are constantly challenged by oxidants in the form of free radicals generated by the conversion of oxyhaemoglobin to deoxyhaemoglobin and by peroxides generated by phagocytosing granulocytes
- Failure to withstand oxidative stress damages sulphydryl groups in haemoglobin and the red cell membrane and causes haemolysis
How would a patient with Glucose-6-Phosphate Dehydrogenase Deficiency anaemia present (5)?
Common:
* Presence of risk factors (Fx)
* Pallor
* Jaundice
* Episodic dark urine (haemoglobinuria)
* Nausea
Uncommon:
* Cataract
* Splenomegaly
What investigations are recommended in suspected Glucose-6-Phosphate Dehydrogenase Deficiency anaemia (7)?
- FBC
- Reticulocyte count
- Peripheral smear
- Serum bilirubin
- Lactate dehydrogenase (LDH)
- Haptoglobin
- Urinalysis
What would is the diagnostic result of FBC in Glucose-6-Phosphate Dehydrogenase Deficiency anaemia?
- Hb
- MCHC
- MCV
- Platelet
- WBC count
- Hb: reduced
- MCHC: elevated
- MCV: elevated
- Platelet and WBC count: usually normal (with concurrent viral infection may be reduced)
What would is the diagnostic result of reticulocyte count in Glucose-6-Phosphate Dehydrogenase Deficiency anaemia?
Elevated
What would is the diagnostic result of urinalysis in Glucose-6-Phosphate Dehydrogenase Deficiency anaemia?
Haemoglobinuria
What would is the diagnostic result of lactate dehydrogenase (LDH) in Glucose-6-Phosphate Dehydrogenase Deficiency anaemia?
High
What would is the diagnostic result of haptoglobin in Glucose-6-Phosphate Dehydrogenase Deficiency anaemia?
Low
What would is the diagnostic result of peripheral blood smear in Glucose-6-Phosphate Dehydrogenase Deficiency anaemia?
Anisocytosis, abnormal forms, bite cells
What is the management of a patient with Glucose-6-Phosphate Dehydrogenase Deficiency anaemia with acute haemolysis (2)?
Supportive care + Folic acid
What is the management of a neonate patient with Glucose-6-Phosphate Dehydrogenase Deficiency anaemia with prolonged indirect hyperbilirubinaemia (2)?
Phototherapy
What is the management of a patient with Glucose-6-Phosphate Dehydrogenase Deficiency anaemia with chronic non-spherocytic haemolytic anaemia (2)?
Supportive care + Folic acid
