Quick Facts
- Sample: Whole blood (EDTA or ACD tube)
- Fasting: Not required
- Turn-around: Typically 3–5 business days
Note: Quest Diagnostics and Labcorp may report G6PD results differently. Labcorp may include an RBC count, while Quest Diagnostics typically reports only G6PD activity, but both tests measure the same enzyme.
Benefits
- Know your G6PD enzyme status before a medication triggers a hemolytic crisis.
- Screen privately and conveniently—no specialist referral required.
- Results are normalized to hemoglobin for reliable interpretation across varying red blood cell counts.
- Identify inherited risk early, even when you feel completely well.
- Supports safer travel, infection treatment planning, and malaria drug decisions.
- Empowers you to protect family members who may share the same inherited risk.
Who Is This Test For?
- People with unexplained or recurring hemolytic anemia seeking a clear diagnosis.
- Anyone with a family history of G6PD deficiency or related enzyme disorders.
- Individuals of African, Middle Eastern, Mediterranean, or South/Southeast Asian ancestry, where prevalence is significantly higher.
- Patients about to start medications that can trigger oxidative stress (e.g., primaquine, dapsone, certain antibiotics).
- Anyone who wants proactive screening before travel to malaria-endemic regions requiring antimalarial drugs.
How It Works – Just 3 Steps
- Order online — Select the quantitative G6PD test, complete your health profile, and receive a lab requisition instantly.
- Visit a draw site — A technician collects a small whole-blood sample; no fasting needed.
- Review your results — Results arrive securely online, with reference ranges and guidance on next steps.
FAQ
What does "quantitative" mean for this test? It measures the actual activity level of the G6PD enzyme in units per gram of hemoglobin, rather than just flagging it as present or absent. This gives a more precise picture of your risk.
Do I need to fast before the test? No fasting is required. However, let your provider know about any recent blood transfusion, active illness, or ongoing hemolytic episode, as these can temporarily raise results and mask true deficiency. (ARUP Consult 2025 — source)
Can a normal result rule out G6PD deficiency? Not always. Testing during or shortly after a hemolytic episode—or right after a transfusion—can produce falsely normal results due to elevated reticulocytes. Repeat testing 2–3 months later may be recommended. (ARUP Consult 2025 — source)
Is this test the same as a genetic test? No. This assay measures enzyme activity in your red blood cells, not the underlying gene variant. Genetic testing is a separate, more detailed step if needed.
Who is most at risk for G6PD deficiency? G6PD deficiency affects more than 400 million people worldwide and is the most common enzymatic disorder of red blood cells. Risk is higher in people of African, Middle Eastern, Mediterranean, and Southeast Asian descent, and in males. (WHO 2018 — source)
More Details
What is the purpose of this test?
The quantitative G6PD blood test measures the activity of glucose-6-phosphate dehydrogenase, an enzyme that shields red blood cells from oxidative damage. When activity is too low, exposure to certain drugs, infections, or foods (like fava beans) can trigger the destruction of red blood cells—a condition called hemolytic anemia. Early detection lets you take preventive steps before a crisis occurs. (NCBI / NIH 2025 — source)
Who would benefit from this test?
You may benefit if you have unexplained or episodic anemia, a family history of G6PD deficiency, or ancestry from a higher-prevalence region. It is also valuable before starting medications known to stress red blood cells, or if prior lab work raised concern. A 2023 systematic review found prevalence across Arab countries ranging from 2% to 31%, illustrating how widely this condition varies by population. (Journal of Clinical Medicine 2023 — source)
When should I order the G6PD test?
Order this test before beginning any medication associated with oxidative stress—especially antimalarials like primaquine, which the WHO specifically flags as a trigger for acute hemolytic anemia in people with G6PD deficiency. (WHO 2018 — source) It is also appropriate when you have symptoms of hemolysis (dark urine, jaundice, rapid heart rate, fatigue) or when recurrent anemia has no clear cause.
How do I interpret the results?
Results are reported in units per gram of hemoglobin (U/g Hb) and compared against age-specific reference intervals. For adults, ARUP Consult lists a normal reference interval of 9.6–16.3 U/g Hb.
- 9.6–16.3 U/g Hb — Normal enzyme activity: No immediate action needed; note timing if hemolysis is suspected.
- Below reference range — Reduced activity, consistent with deficiency: Discuss with a clinician and avoid known triggers.
- Borderline / low-normal — Possible partial deficiency or masked result: Repeat testing 2–3 months after any hemolytic episode.
- If your sample was collected during or right after a hemolytic episode, even a low-normal result should be interpreted cautiously—reticulocytes and transfused cells can temporarily elevate the measured activity and hide true deficiency.
Pre-test preparation
No fasting is needed. Disclose any recent blood transfusion, active illness, or known ongoing hemolysis before testing, as all three can cause falsely normal results. If you are being tested specifically to assess safety before starting a new drug, bring a list of current medications. The specimen is whole blood; it should be kept refrigerated and processed promptly. (ARUP Consult 2025 — source)
How often should I get tested?
- Initial screening (no prior diagnosis): Once, unless the result is borderline or timing is uncertain.
- Tested during or soon after a hemolytic episode: Repeat at least 2–3 months after the episode resolves.
- Known deficiency, stable and asymptomatic: No routine repeat needed; retest if symptoms change.
- Before starting a new high-risk medication: Before each new medication course if deficiency status is unknown.
Why early detection matters
G6PD deficiency stays silent until a trigger strikes—and when it does, the resulting hemolytic anemia can be severe. Because the condition affects more than 400 million people worldwide and is the most common enzymatic disorder of red blood cells, many people carry it unknowingly. (WHO 2018 — source) Identifying low enzyme activity before drug exposure, infection, or travel gives you actionable information to protect your health and guide your clinician's prescribing decisions.
Related tests you may consider
Complete Blood Count (CBC) with Differential and Platelets Blood Test—Evaluates blood cell types and levels to help diagnose health conditions and track treatment response.
Reticulocyte Count Blood Test — Evaluates erythropoietic activity which is increased in acute and chronic hemorrhage and hemolytic anemias, and evaluate erythropoietic response to antianemic therapy.
Wellness #2 Essential Blood Test Panel plus Vitamin D — Helps to evaluate overall health status. It helps identify potential issues or abnormalities
