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Diagnostic Tests: Peripheral Smear Findings in G6PD Deficiency
Overview — What the Peripheral Smear Shows
This peripheral smear demonstrates Heinz bodies, which are inclusions formed by precipitated, oxidized hemoglobin inside red blood cells. These occur when RBCs are exposed to oxidative stress in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency.
G6PD deficiency is an X-linked recessive condition and is particularly common in African-American males (10–15%).
Clinical Scenario — When This Is the Correct Answer
You should suspect G6PD deficiency when the presentation describes a previously healthy male who suddenly develops signs of acute intravascular hemolysis after oxidative stress. Key features include:
Common triggers of oxidative stress include:
When a question stem includes these triggers plus acute hemolysis and the smear shows characteristic RBC inclusions, G6PD deficiency is the diagnosis.
Other Cells Characteristic of G6PD Deficiency
Once Heinz bodies form, the spleen attempts to remove them. This “pitting” process produces:
Bite cells (degmacytes)
Definitive Diagnostic Test
The definitive test for confirming G6PD deficiency is:
Measurement of G6PD enzyme level
Important caveat:
You must wait approximately 2 months after the hemolytic episode to test.
Immediately after hemolysis, the older, most deficient red cells have already been destroyed. The remaining population consists of young reticulocytes with relatively higher G6PD activity, which can give a false-normal result.
If you’d like, I can also create a comparison chart of G6PD deficiency vs. other hemolytic anemias (like autoimmune hemolysis or sickle cell), or provide a rapid-review summary for exams.
Overview — What the Peripheral Smear Shows
This peripheral smear demonstrates Heinz bodies, which are inclusions formed by precipitated, oxidized hemoglobin inside red blood cells. These occur when RBCs are exposed to oxidative stress in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency.
G6PD deficiency is an X-linked recessive condition and is particularly common in African-American males (10–15%).
Clinical Scenario — When This Is the Correct Answer
You should suspect G6PD deficiency when the presentation describes a previously healthy male who suddenly develops signs of acute intravascular hemolysis after oxidative stress. Key features include:
- Weakness and fatigue
- Tachycardia
- Jaundice
- Dark urine (hemoglobinuria)
- Sudden drop in hemoglobin
Common triggers of oxidative stress include:
- Infections (most common cause)
- Drugs, including:
- Sulfa drugs
- Primaquine
- Dapsone
- Quinidine
- Nitrofurantoin
- Fava beans (favism)
When a question stem includes these triggers plus acute hemolysis and the smear shows characteristic RBC inclusions, G6PD deficiency is the diagnosis.
Other Cells Characteristic of G6PD Deficiency
Once Heinz bodies form, the spleen attempts to remove them. This “pitting” process produces:
Bite cells (degmacytes)
- RBCs appear as though a bite has been taken out of them.
- These cells are classic for G6PD deficiency and often accompany Heinz body formation.
Definitive Diagnostic Test
The definitive test for confirming G6PD deficiency is:
Measurement of G6PD enzyme level
Important caveat:
You must wait approximately 2 months after the hemolytic episode to test.
Immediately after hemolysis, the older, most deficient red cells have already been destroyed. The remaining population consists of young reticulocytes with relatively higher G6PD activity, which can give a false-normal result.
If you’d like, I can also create a comparison chart of G6PD deficiency vs. other hemolytic anemias (like autoimmune hemolysis or sickle cell), or provide a rapid-review summary for exams.
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