[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Red cells and bleeding disorders](https://durgical.com/en/general-pathology/areas/red-cells/) › G6PD deficiency: oxidant haemolysis, Heinz bodies and bite cells

# G6PD deficiency: oxidant haemolysis, Heinz bodies and bite cells

- Lesion

Red cells cannot defend against oxidants. After certain drugs, infections or fava beans, haemoglobin clumps and cells burst a few days later.

Updated Nov 12, 2026

## Key points

- X-linked recessive: mostly affects males.
- Triggers: infections (the commonest), oxidant drugs (primaquine, dapsone, sulfonamides, nitrofurantoin, rasburicase) and fava beans.
- Heinz bodies (precipitated haemoglobin, supravital stain) and bite cells on the smear.
- Haemolysis begins two to three days after exposure and stops as older cells are cleared (G6PD A−).
- Can cause neonatal jaundice; the Mediterranean variant is more severe.

## What it is

Glucose-6-phosphate dehydrogenase (G6PD) supplies NADPH through the pentose phosphate pathway, keeping glutathione reduced so red cells can neutralize oxidants. The deficiency is X-linked and very common in malaria-endemic regions, because it protects against falciparum malaria. Most variants make a normal-functioning but unstable enzyme, so older red cells are the most deficient. Oxidant stress denatures haemoglobin into Heinz bodies, causing intravascular and extravascular haemolysis that is usually episodic and self-limited.

## Structure

- Smear during a crisis: bite cells, blister cells, some spherocytes, reticulocytosis in recovery.
- Supravital (crystal violet) stain: Heinz bodies attached to the membrane.

## Step by step

- An oxidant (from infection, drug or fava beans) generates hydrogen peroxide inside red cells.
- Low G6PD activity means too little NADPH to regenerate reduced glutathione.
- Haemoglobin sulfhydryl groups oxidize; globin denatures and precipitates as Heinz bodies.
- Heinz bodies damage the membrane: some cells lyse inside vessels.
- Splenic macrophages pluck out the inclusions, leaving bite cells, then remove the damaged cells.
- Older, enzyme-poor cells die first; reticulocytes with more enzyme survive and the episode ends.

## Markers

- Heinz bodies
- Bite cells
- G6PD activity assay

## Clinical notes

- Sudden pallor, jaundice, dark urine and back pain a few days after an infection or drug.
- Screening matters before primaquine for vivax malaria, which is common in Colombia.
- Measuring G6PD during a crisis can be falsely normal because young cells have more enzyme.

## Memory aid

Fava, fever or a pill: no NADPH, no glutathione, Heinz bodies form and the spleen takes a bite.

## Test yourself

Think of the answer, then tap the question to see it.

## Why does haemolysis in G6PD A− deficiency stop even if the drug is continued?

Older cells with the least enzyme are destroyed first; the young cells that replace them have enough activity to resist.

## What are Heinz bodies?

Precipitates of oxidized, denatured haemoglobin attached to the red cell membrane, seen with supravital stains.

## Why is G6PD deficiency common in some populations?

It protects heterozygotes against severe falciparum malaria.

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## Elsewhere in DurgiPedia

- [Glucose-6-phosphate dehydrogenase (G6PD)](https://durgical.com/en/biochemistry/enzymes/glucose-6-phosphate-dehydrogenase/)
- [Hemoglobin and 2,3-BPG](https://durgical.com/en/biochemistry/enzymes/hemoglobin-and-2-3-bpg/)

## Connections

## Related 4

- [Oxidative stress and free-radical injury](https://durgical.com/en/general-pathology/oxidative-stress-and-free-radical-injury/)
- [Haemolysis: extravascular vs intravascular](https://durgical.com/en/general-pathology/haemolysis-extravascular-vs-intravascular/)
- [Red cell morphology on the smear](https://durgical.com/en/general-pathology/red-cell-morphology-on-the-smear/)
- [Mendelian inheritance: autosomal dominant, recessive and X-linked](https://durgical.com/en/general-pathology/mendelian-inheritance-autosomal-dominant-recessive-and-x-linked/)

## Related conditions 3

- [Glucose-6-phosphate dehydrogenase (G6PD) deficiency](https://durgical.com/en/conditions/glucose-6-phosphate-dehydrogenase-deficiency/)
- [Neonatal jaundice](https://durgical.com/en/conditions/neonatal-jaundice/)
- [Malaria](https://durgical.com/en/conditions/malaria/)

## Microorganisms 1

- [Plasmodium falciparum](https://durgical.com/en/microbiology/plasmodium-falciparum/)

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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [G6PD gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/g6pd/) (MedlinePlus, US National Library of Medicine, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/general-pathology/g6pd-deficiency-oxidant-haemolysis-heinz-bodies-and-bite-cells/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/g6pd-deficiency-oxidant-haemolysis-heinz-bodies-and-bite-cells/