Glucose-6-Phosphate Dehydrogenase (G6PD) – Qualitative Test

The Glucose-6-Phosphate Dehydrogenase (G6PD) qualitative test is used to screen for G6PD deficiency, a genetic condition in which red blood cells break down prematurely (hemolysis) in response to certain stressors like infections, medications, or foods. G6PD deficiency is more common in males and certain ethnic groups and can cause hemolytic anemia.

1. What Is G6PD?

• G6PD is an enzyme that helps protect red blood cells from oxidative damage.

• It is essential in the pentose phosphate pathway, which produces NADPH, a molecule critical for red blood cell survival under stress.

• G6PD deficiency is an inherited X-linked disorder that affects the stability of red blood cells.

2. Why Is the G6PD Qualitative Test Performed?

This test is used to:

• Screen for G6PD deficiency, especially in individuals from at-risk populations (e.g., African, Mediterranean, or Asian descent).

• Evaluate unexplained hemolytic anemia or jaundice.

• Prevent complications from medications or foods that can trigger hemolysis (e.g., sulfa drugs, fava beans).

3. G6PD Qualitative Test Results

• Normal: Sufficient G6PD activity detected – no deficiency present.

• Deficient: Reduced or absent G6PD activity – indicative of G6PD deficiency.

• Intermediate: Partial deficiency may be seen in some heterozygous females due to X-chromosome inactivation.

4. How to Interpret Results

🔹 G6PD Deficient:

• High risk for hemolysis when exposed to oxidative stressors such as certain drugs, infections, or foods (especially fava beans).

• Requires avoidance of triggering agents and education on emergency symptoms.

🔹 Normal G6PD:

• Indicates no enzyme deficiency and low risk for related hemolytic anemia.

5. What Can Affect the Test?

• Recent blood transfusion (can mask deficiency).

• Acute hemolytic episode (younger red blood cells may show normal enzyme activity).

• Female carriers may show intermediate or variable results due to X-inactivation.

6. How Is the Test Performed?

• A blood sample is taken from a vein or heel/finger stick (in newborn screening).

• Qualitative tests detect enzyme presence or absence rather than measuring its exact activity.

7. When to See a Doctor

🚨 Speak with your healthcare provider if you:

• Have a family history of G6PD deficiency.

• Develop symptoms like jaundice, dark urine, or sudden fatigue after exposure to certain drugs or foods.

• Are planning to take new medications that may trigger hemolysis.

🔹 Key Takeaways

✅ G6PD qualitative testing identifies individuals at risk for hemolytic anemia due to enzyme deficiency.

✅ A deficient result requires lifestyle modifications and medication precautions.

✅ Accurate diagnosis is critical to prevent potentially life-threatening episodes.