G6PD

Anemia

Report in 72Hrs

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No Fasting Required

Details

Enzyme test for glucose-6-phosphate dehydrogenase.

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G6PD Test - Comprehensive Medical Information Guide

Why is it done?
- Measures the activity of glucose-6-phosphate dehydrogenase enzyme in red blood cells
- Diagnoses G6PD deficiency, an inherited condition affecting red blood cell metabolism
- Screens for hemolytic anemia risk and predisposition to acute hemolytic episodes
- Identifies candidates at risk for severe reactions to certain medications (antimalarials, sulfonamides, aspirin)
- Evaluates unexplained hemolytic anemia or jaundice, particularly in newborns
- Routine newborn screening in high-risk populations (Mediterranean, African, Asian descent)
- Typically performed upon clinical suspicion, family history of deficiency, or during newborn screening programs
Normal Range
- Normal G6PD Activity: 4.6 to 13.5 IU/g hemoglobin (or 5 to 15 U/g Hb depending on laboratory)
- Units of Measurement: International Units per gram of hemoglobin (IU/g Hb) or U/g Hb
- Result Interpretation:
- Normal: Enzyme activity within reference range indicates adequate G6PD enzyme present
- Low/Deficient: Activity below normal range suggests partial or complete G6PD deficiency
- Borderline: Activity in borderline range may indicate carrier status or intermediate deficiency
- Note: Reference ranges may vary by laboratory and testing methodology; confirm with your specific lab
Interpretation
- Normal Activity (>5 IU/g Hb): No G6PD deficiency detected; red blood cells have adequate enzyme to protect against oxidative stress
- Mild Deficiency (3-5 IU/g Hb): Partial enzyme deficiency present; hemolytic episodes possible with significant oxidative triggers
- Moderate Deficiency (1-3 IU/g Hb): Significant enzyme deficiency; increased risk of hemolytic episodes with triggering agents
- Severe Deficiency (<1 IU/g Hb): Severe enzyme deficiency; pronounced risk of hemolytic crises with minimal triggers or spontaneously
- Factors Affecting Results:
- Age: Reticulocytosis may elevate enzyme levels; acute hemolysis can falsely lower results
- Sex: X-linked inheritance means males typically show more severe deficiency than heterozygous females
- Recent Hemolysis: Hemolytic episodes trigger reticulocytosis with newer RBCs containing more enzyme
- Transfusion: Recent blood transfusion may mask deficiency if normal RBCs transfused
- Ethnic Variants: Over 400 genetic variants exist; different variants produce different enzyme levels and clinical severity
- Clinical Significance:
- Deficient individuals must avoid triggering factors: antimalarial drugs (primaquine, pamaquine), sulfonamides, high-dose aspirin, sulfonylureas, and fava beans
- Heterozygous females may show variable enzyme activity due to X-chromosome inactivation patterns
Associated Organs
- Primary Organ Systems:
- Hematopoietic System: Red blood cells directly affected; bone marrow stressed during hemolytic episodes
- Spleen: Enlarged spleen (splenomegaly) common due to increased destruction of defective RBCs
- Diseases and Conditions Associated with Abnormal Results:
- Acute Hemolytic Anemia: Sudden onset hemolysis triggered by infection, medications, or fava bean ingestion
- Chronic Hemolytic Anemia: Ongoing low-level hemolysis producing chronic anemia in severe deficiency
- Neonatal Jaundice: Severe hyperbilirubinemia in newborns with G6PD deficiency requiring phototherapy
- Kernicterus: Risk of permanent brain damage if severe neonatal jaundice untreated
- Potential Complications:
- Hemolytic Crisis: Severe acute hemolysis with dark urine, fatigue, jaundice, and respiratory distress
- Acute Kidney Injury: Severe hemolysis can precipitate renal damage from hemoglobin precipitation
- Cholelithiasis: Chronic hemolysis increases bilirubin stones in gallbladder
- Iron Overload: Chronic transfusions for severe cases can cause secondary hemochromatosis affecting heart and endocrine organs
Follow-up Tests
- Initial Follow-up Tests for Confirmed Deficiency:
- Complete Blood Count (CBC): Assess hemoglobin, hematocrit, reticulocyte count, and platelet levels
- Peripheral Blood Smear: Examine RBC morphology for signs of hemolysis or Heinz bodies
- Reticulocyte Count: Measure bone marrow response to hemolysis
- Bilirubin (Total and Direct): Evaluate hemolysis severity and jaundice risk
- Lactate Dehydrogenase (LDH): Assess hemolysis extent; elevated in acute episodes
- Haptoglobin: Decreased with active hemolysis
- Genetic Testing:
- DNA Sequencing: Identify specific G6PD gene variant to predict severity and prognosis
- During Acute Hemolytic Episodes:
- Urinalysis: Check for hemoglobinuria (dark urine indicating severe hemolysis)
- Creatinine and Blood Urea Nitrogen: Screen for acute kidney injury
- Electrolytes: Monitor potassium and other ions for hemolysis complications
- Monitoring Frequency for Ongoing Conditions:
- Stable Chronic Deficiency: Annual CBC and clinical assessment; baseline imaging of spleen
- Neonatal Cases: Follow-up bilirubin testing at 24-48 hours if jaundice present; repeat G6PD test at 3 months when neonatal effects resolve
- Post-Hemolytic Crisis: Repeat CBC and hemolysis markers weekly until values stabilize
- Related Complementary Tests:
- Osmotic Fragility Test: Evaluate RBC stability and exclude other hemolytic anemias
- Heinz Body Stain: Visualize precipitated hemoglobin in RBCs indicating oxidative damage
- Pyruvate Kinase Activity: Rule out concurrent pyruvate kinase deficiency in selected cases
Fasting Required?
- Fasting Requirement: No
- The G6PD test does not require fasting or dietary restrictions
- Special Instructions and Patient Preparation:
- Can eat and drink normally before the test
- Avoid scheduling during or immediately after acute hemolytic episode if possible, as recent hemolysis affects enzyme measurement accuracy
- Inform healthcare provider if recent transfusion received (within 3 months), as transfused normal RBCs may mask deficiency
- Simple arm preparation: Standard venipuncture; no special skin preparation needed beyond routine cleaning
- Medications:
- No medications need to be stopped or adjusted before the test
- However, if taking medications that trigger hemolysis (antimalarials, sulfonamides, aspirin), inform provider as these may affect interpretation
- Sample Collection:
- Venous blood sample collected in EDTA-anticoagulant tube (purple-top tube)
- For newborn screening: Dried blood spot from heel prick collected on filter paper

How our test process works!