Short answer
Bite cells, also called degmacytes, are red blood cells with a semicircular defect at the edge. They usually appear when the spleen removes a damaged hemoglobin inclusion, so the finding is a clue to oxidative hemolysis rather than a diagnosis by itself. G6PD deficiency is the classic association, but medicines, infections, fava beans, and unstable hemoglobins can create the same pattern.
How to frame the finding
| Pattern | Common next question | Why it matters |
|---|---|---|
| Bite cells with jaundice, dark urine, or falling hemoglobin | Is active hemolysis already happening? | That pattern makes the finding more urgent and pushes hemolysis labs to the front. |
| Bite cells after a new drug, infection, or fava bean exposure | Could an oxidant trigger be the cause? | Trigger review matters most when the timing fits G6PD-type hemolysis. |
| Bite cells with suspected Heinz bodies or blister cells | Was a supravital stain or hematology review done? | Routine Wright-stained smears may miss the inclusion that explains the bite cell. |
| Bite cells with an otherwise quiet CBC | Should the smear be reviewed again in context? | An isolated comment is less informative than a pattern tied to anemia markers. |
What to check next
- Are hemoglobin, reticulocytes, bilirubin, LDH, haptoglobin, and creatinine abnormal?
- Is there jaundice, dark urine, fatigue, shortness of breath, pallor, or tachycardia?
- Were sulfa drugs, dapsone, nitrofurantoin, antimalarials, rasburicase, or a recent infection part of the story?
- Would a G6PD test be meaningful now, or would timing after recovery be safer if acute hemolysis could distort the result?
- Should the smear be reviewed for Heinz bodies, blister cells, or other inclusion clues?
When follow-up matters more
Follow-up matters more when bite cells appear with hemolysis markers, jaundice, dark urine, a new medicine exposure, or a history that fits oxidant stress. In that case, G6PD timing, repeat smear review, and hemolysis labs matter more than the shape comment alone.
Questions to ask
- Did the report say bite cells, blister cells, or degmacytes?
- Are the bite cells isolated, or do they appear with other hemolysis clues on the smear?
- Is there a known history of G6PD deficiency, unstable hemoglobin, or prior oxidant hemolysis?
- Should retesting, hemolysis labs, or hematology review happen sooner because of symptoms?
When follow-up is more urgent
If bite cells appear with dark urine, yellowing of the eyes, chest pain, shortness of breath, weakness, or a fast hemoglobin drop, the question is no longer just what the smear shows. Prompt evaluation matters because oxidant hemolysis can worsen quickly, especially after a trigger exposure or infection.
How hemolysis references help
Merck's hemolysis overview helps show why bite cells are read with the rest of the hemolysis pattern. If LDH is high, haptoglobin is low, bilirubin is rising, or a trigger exposure fits, the smear comment becomes much more actionable than it would be in isolation.
When a blood-smear reference matters more
MedlinePlus blood-smear guidance matters when a red-cell shape finding needs to be interpreted as a pattern rather than a diagnosis. It helps anchor the result in smear quality, repeat review, and the CBC or hemolysis context that decides how seriously to take one abnormal shape.
FAQ
What are bite cells on a blood smear?
Bite cells are red blood cells with a piece missing from the edge. They are a morphology clue that often reflects prior oxidative injury to hemoglobin.
What do bite cells suggest?
They most often suggest oxidative hemolysis. G6PD deficiency is the classic cause, but medicines, infection, fava beans, and unstable hemoglobins can also fit.
What is the link between bite cells and Heinz bodies?
Heinz bodies are denatured hemoglobin inclusions. The spleen can remove the damaged portion and leave behind the bite-shaped defect seen on the smear.
What tests usually follow bite cells?
A clinician often checks CBC trends, reticulocytes, bilirubin, LDH, haptoglobin, kidney function, and G6PD testing when the trigger pattern fits.
Can bite cells appear after a medicine or infection?
Yes. Oxidant medicines and acute infections can trigger hemolysis, especially in people with G6PD deficiency or other limited red-cell antioxidant defenses.
When are bite cells more urgent?
They are more concerning when they appear with anemia symptoms, jaundice, dark urine, low haptoglobin, high LDH, rising bilirubin, or a clear recent oxidant exposure.