Home Biomarkers G6PD (Quantitative)

G6PD (Quantitative)

Anemia Biomarker

Sample Needed

Collection Type: Blood

Body System

Related System: Anemia

Overview

Glucose-6-phosphate dehydrogenase (G6PD) is an enzyme in red blood cells that helps protect them from oxidative damage by maintaining reduced glutathione. The quantitative G6PD assay measures enzyme activity (usually reported as U/g hemoglobin) to detect deficiency. Low activity suggests G6PD deficiency, an X‑linked genetic condition that predisposes to hemolytic anemia when exposed to oxidative stress (certain drugs, infections, fava beans). Indications include unexplained hemolysis, neonatal jaundice, dark urine, pallor or fatigue. Prevalence and baseline activity vary by sex (males more often affected), ethnicity (higher in African, Mediterranean, Middle Eastern, and Southeast Asian populations) and recent hemolysis or transfusion (which can alter measured activity).

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Test Preparation

No special preparation is required

Why Do I Need This Test

Profile: included in Anemia investigations (hemolysis workup) and neonatal jaundice evaluation.
Symptoms: sudden anemia, jaundice, dark urine, unexplained fatigue, neonatal hyperbilirubinemia.
Diagnoses/monitoring: confirms G6PD deficiency and helps assess hemolysis risk.
Causes of abnormal: inherited enzyme deficiency, recent hemolysis, recent transfusion, reticulocytosis, laboratory variability.
Biological meaning: low values indicate red cells are vulnerable to oxidative injury.
Behaviors: exposure to oxidant drugs, infections, or fava beans can precipitate hemolysis.
Family history of G6PD deficiency or hemolytic episodes suggests testing.

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Understanding Test Results

Because reference methods vary, deficiency is usually defined relative to the laboratory’s normal activity.
General interpretive thresholds: Severe deficiency (<10% activity): very high risk of hemolysis (often corresponds to very low absolute values, e.g., markedly below the lab’s lower limit).
Deficiency (<30% of normal activity; typically correlates roughly to <2–4 U/g Hb depending on the lab): diagnostic of G6PD deficiency and risk of acute hemolysis with oxidant exposure.
Intermediate activity (≈30–80% of normal; often seen in heterozygous females): variable risk; some exposures may cause hemolysis.
Normal activity (within the stated range 7.0–20.5 U/g Hb): unlikely to have clinically significant G6PD deficiency.
Causes of falsely normal or high results include recent transfusion or reticulocytosis (young red cells have higher G6PD).
Low values require correlation with clinical history and sometimes repeat testing when hemolysis has settled.

Normal Range

7.0-20.5 U/g Hb

FAQs

Q: What is G6PD quantitative test?

A: A G6PD quantitative test measures the activity level of the glucose‑6‑phosphate dehydrogenase enzyme in red blood cells to diagnose G6PD deficiency and assess severity. It provides a numerical enzyme activity value, helps predict risk of hemolysis, guides medication and transfusion decisions, and is used in newborn screening and anemia workups. Results can be affected by recent transfusion or high reticulocyte counts.

Q: What does it mean if G6PD is high?

A: A high G6PD result usually isn’t a disease by itself. It often reflects recent hemolysis or a blood transfusion (young red cells and reticulocytes have higher enzyme activity), lab variation, or high white cell counts. It can be misleading during acute illness. If unexpected, repeat testing once blood is stable (often after several weeks) and discuss results with your clinician.

Q: What is the normal result of a G6PD confirmatory test?

A: A normal G6PD confirmatory test shows enzyme activity within the laboratory’s reference range (typically reported as \

Q: What is the qualitative method of G6PD?

A: The qualitative method for G6PD screening detects presence or absence of enzyme activity rather than measuring levels. Common techniques include the fluorescent spot test or rapid bedside kits, which give a fluorescence or color change if activity is adequate. Results are reported as normal, intermediate or deficient. Limitations: it cannot quantify activity and may miss heterozygous females or be falsely normal after transfusion or hemolysis.

Q: Is G6PD deficiency serious?

A: G6PD deficiency ranges from mild to potentially serious. Many people are asymptomatic, but triggers (certain drugs, infections, fava beans, some chemicals) can cause acute hemolytic anemia and neonatal jaundice. Severe episodes may lead to profound anemia, kidney injury, or rarely death. Avoid known triggers, check medications with a clinician, and seek prompt medical care for jaundice, dark urine, weakness, or breathlessness.

Q: Can G6PD eat orange?

A: Yes people with G6PD deficiency can eat oranges. Citrus fruits are not known triggers of oxidative hemolysis. Common dietary triggers include fava beans and some legumes; more important triggers are certain drugs (for example primaquine, sulfa drugs) and chemicals. Normal amounts of orange or juice are safe; avoid very large therapeutic vitamin C doses and consult a clinician if you develop jaundice or dark urine.