G6PD deficiency is an inherited X-linked enzyme defect that leaves red blood cells unable to handle oxidative stress, so they break down after certain triggers. It is common in people of African, Mediterranean, Middle Eastern and Asian descent, mostly affects males, and most people feel well until exposed to an infection, a drug or fava beans.
Key symptoms
- Sudden fatigue, pallor and shortness of breath 1 to 3 days after a trigger
- Dark, tea-colored urine
- Yellow skin or eyes
- Back or belly pain
- Jaundice in newborns
What you find on exam
- Pallor and yellow sclera
- Fast heart rate
- Mildly enlarged spleen in some patients
- Ask about recent drugs, infections and fava beans
Tests
- Blood count: falling hemoglobin with a rising reticulocyte count
- Smear: bite cells, blister cells and Heinz bodies on a special stain
- Hemolysis labs: high LDH and indirect bilirubin, low haptoglobin; negative Coombs test
- G6PD enzyme assay, repeated after recovery because recent hemolysis can give a false normal
Treatment basics
- Stop and avoid triggers: primaquine, dapsone, rasburicase, nitrofurantoin, sulfonamides, methylene blue
- Avoid fava beans and naphthalene mothballs
- Treat any infection; give fluids and transfuse if anemia is severe
- Newborns: phototherapy, and exchange transfusion if jaundice is severe
- Test for G6PD before giving primaquine, tafenoquine, dapsone or rasburicase
Red flags
- Rapid drop in hemoglobin with breathlessness or chest pain
- Dark urine with falling urine output (kidney injury)
- Newborn with early or severe jaundice
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.