Analysis of favism Preparation steps and accurate interpretation of results

Have you ever experienced sudden fatigue, weakness, or yellowing of the skin? The cause might be G6PD deficiency (Favism), a genetic condition that affects red blood cells. The G6PD test is a medical examination that helps detect this condition early in both adults and children, including infants, and can help prevent serious complications in the future. article we’ll walk you through everything you need to know about this test: when it’s done, how it’s performed, necessary preparations, result interpretation, and key points to be aware of before and after the test.

What is the G6PD (Favism) Test?

The G6PD test is a blood test that measures the activity of the G6PD enzyme, which is crucial for the health of red blood cells. This test is usually requested if a doctor suspects G6PD deficiency (Favism), a genetic condition that can lead to hemolytic anemia.

Why is the test requested?

To confirm a G6PD enzyme deficiency.
To determine the cause of hemolytic anemia.
Before prescribing certain medications that may be harmful to people with the deficiency.
For newborns, to detect deficiency early and prevent jaundice or anemia.

Does the test require fasting?

❌ No fasting is required.
✔️ However, it is recommended to:

Avoid medications or supplements that affect the enzyme before the test.
Inform the doctor about any recent illnesses or symptoms.

How is the test performed?

A small blood sample is taken from a vein or fingertip.
The sample is sent to the laboratory to measure enzyme activity.

Can infants take the test?

✔️ Yes, using smaller blood samples suitable for their age.

Normal values vary with age.
Requires careful medical interpretation.

What are normal values?

Values vary depending on the lab and testing method.
Normal enzyme activity means red blood cells are protected.
Deficiency may be partial or complete, affecting the severity of symptoms.

What do the results mean?

Normal activity: No problem; most foods and medications are safe.
Partial or complete deficiency: Increased risk of hemolysis with certain foods or drugs, requiring careful medical follow-up.

Are there any risks from the test?

✔️ The test is very safe.
❌ Minor risks may include:

Slight numbness or small bruise at the blood draw site.

Can medications affect the results?

✔️ Yes, some drugs may temporarily reduce or alter enzyme activity, such as:

Antimalarial drugs
Certain antibiotics (e.g., sulfa drugs)
Magnesium supplements
Heart medications
⚠️ Always inform your doctor of any medications before testing.

When should the test be repeated?

If the sample was invalid or contaminated.
If the test was done during a hemolytic episode.
If medications affected the results.

Can the test show normal results even if there is a deficiency?

✔️ Yes. After a hemolytic episode, new red blood cells containing normal enzyme levels may temporarily give a normal result. It is recommended to wait until recovery from an episode before testing.

Is the test painful?

❌ Usually not; only a small prick is felt during blood collection.

How long until results are ready?

⏱ Usually 1–3 days depending on the lab; sometimes faster if urgent.

Is the G6PD test important before birth?

✔️ Yes, especially if there is a family history of G6PD deficiency. Newborns should be screened to prevent complications.

Can the test be repeated in children?

✔️ Yes, especially after a hemolytic episode or if initial results are unclear.

Can enzyme levels change with age?

✔️ The deficiency is present from birth, but interpretation in infants requires caution due to naturally higher enzyme activity in new red blood cells.

Is the test useful before prescribing new medications?

✔️ Yes, it helps doctors avoid drugs that may trigger hemolysis in people with G6PD deficiency.

Can illness or stress affect the test?

❌ It’s best to wait until recovery from a hemolytic episode or acute illness, as results may be affected.

Does the result affect lifestyle?

✔️ Yes, if G6PD deficiency is detected:

Avoid certain foods (e.g., fava beans, some fruits).
Be cautious with specific medications and supplements.
Regular medical follow-up may be needed.

Can the deficiency be partial?

✔️ Yes, there can be partial or complete deficiency:

Partial: Some red blood cells have normal enzyme, some do not.
This affects symptom severity and the likelihood of hemolytic episodes.

What Does the G6PD (Favism) Test Reveal?

1️⃣ G6PD Enzyme Deficiency:

If the test shows low enzyme activity, it indicates G6PD deficiency (Favism).
Red blood cells become more vulnerable to breakdown when exposed to certain foods, medications, or infections.

2️⃣ Risk of Hemolytic Anemia:

People with G6PD deficiency may have faster red blood cell breakdown, leading to hemolytic anemia, which can appear as:
- Severe fatigue
- Pale skin
- Yellowing of the skin and eyes (jaundice)
- Increased heart rate

3️⃣ Severity of Deficiency:

The test shows whether the deficiency is partial or severe, helping the doctor to:
- Prescribe safe medications
- Avoid prohibited foods
- Monitor health closely

4️⃣ Genetic Status:

The test identifies whether a person is a carrier or affected, since G6PD deficiency is usually inherited.

Types of G6PD Tests

1️⃣ Qualitative Enzyme Activity Test (Traditional Test)

Description: A rapid test to determine if enzyme activity is normal or low.
Purpose: Detects the presence of G6PD deficiency without specifying the severity.
Method: Small blood sample from a finger or vein is tested with chemicals to observe enzyme activity.
Use: Quick initial screening, suitable for children and adults before prescribing certain drugs.

2️⃣ Quantitative Enzyme Activity Test

Description: Measures enzyme activity accurately per gram of hemoglobin.
Purpose: Determines the degree of G6PD deficiency (partial or complete).
Method: Blood sample analyzed with precise lab instruments.
Use: Essential for accurate diagnosis and patient follow-up.

3️⃣ Molecular / DNA Test

Description: Detects genetic mutations causing G6PD deficiency.
Purpose: Identifies the type of deficiency and carrier status, especially in females.
Method: Blood or saliva analyzed for the specific genetic mutation.
Use: Genetic screening for families with a history of the disease.

4️⃣ Oxidative / Challenge Test

Description: Evaluates red blood cells’ response to an oxidizing agent.
Purpose: Determines sensitivity of red blood cells to breakdown in G6PD deficiency.
Method: Sample exposed to an oxidizing substance, enzyme activity or hemolysis is monitored.
Use: Research or assessing severity of deficiency.

Reasons to Perform a G6PD Test

1️⃣ Diagnose G6PD Deficiency

Cause: Genetic enzyme deficiency.
Goal: Identify deficiency, especially if anemia or jaundice occurs after certain foods or medications.

2️⃣ Investigate Hemolytic Anemia

Hemolysis can be triggered by oxidative stress from:
- Fava beans or certain foods
- Specific medications (antimalarials, some antibiotics)
- Infections or illnesses

3️⃣ Assess Risk Before Medication Use

Some drugs can cause red blood cell breakdown.
The test helps the doctor prescribe safe medications.

4️⃣ Genetic Screening / Pre-Marital Testing

Determines carrier or affected status, especially in women.
Helps assess the risk of passing the condition to children.

5️⃣ Evaluate Unexplained Anemia or Jaundice

Helps identify the real cause of symptoms like fatigue, pallor, or jaundice.

6️⃣ Follow-Up for Known Cases

Monitors severity and the effect of foods or drugs that may trigger hemolysis.

How is the G6PD Test Performed?

1️⃣ Type of Sample:

Usually venous blood.
Sometimes a finger-prick drop for rapid tests or for infants.

2️⃣ Venous Blood Collection Steps:

Prepare patient: sit or lie down, clean skin with disinfectant.
Apply tourniquet to locate vein.
Insert needle, draw 2–5 mL of blood.
Remove needle, apply pressure to stop bleeding.
Transfer blood to a sterile tube with anticoagulant and send to lab.

3️⃣ Finger-Prick Sample Steps:

Clean finger, prick with a small needle, collect a drop in a tube or on a slide, and send for testing.

4️⃣ Laboratory Analysis:

Measures enzyme activity in red blood cells using:
- Spectrophotometric assay
- Fluorescent spot test (rapid chemical test)
- Genetic test in specific cases

5️⃣ Test Duration:

Rapid test: 10–30 minutes
Complete test: 1–3 days, depending on the lab

6️⃣ After Sample Collection:

No special precautions needed.
Patients can resume normal activities immediately.

1️⃣ Before the Test

Avoid Certain Medications:
- Antimalarials (e.g., Primaquine)
- Some antibiotics (e.g., Sulfonamides)
- Fever or infection medications
  ✅ Always inform your doctor about any medications or supplements before the test.
Avoid Recent Hemolytic Episodes:
- If you recently had severe anemia or received a blood transfusion, the results may be affected.
Avoid Certain Foods:
- Especially fava beans and some legumes before the test.
General Health Condition:
- You should be relatively stable, without severe infection or active bleeding.
Fasting:
- Usually not required, unless requested by the doctor for other tests.

2️⃣ During Sample Collection

Use sterile equipment to prevent infection.
Collect the sample in a tube containing anticoagulant (EDTA).
Store the sample properly (cold or refrigerated) until it reaches the lab.

3️⃣ After the Test

You can resume normal activities immediately.
Inform your doctor of any medications or foods consumed during the sample collection period for accurate interpretation.

Preparations Before and After the Test

1️⃣ Before the Test

Inform the Doctor about all medications and supplements, including iron and vitamins.
Avoid Hemolytic Episodes: Notify the doctor if in an active anemia episode or recently received a blood transfusion.
Avoid Certain Foods: Fava beans and some legumes.
General Health: Ensure good sleep and avoid excessive stress.

2️⃣ During Sample Collection

Venous Blood: Drawn using sterile equipment.
Infants and Children: Small blood drop from finger or heel is used.
Sample Storage: Keep in an EDTA tube and transfer quickly to the lab.

3️⃣ After the Test

Resume normal activities immediately.
Continue regular medications unless advised otherwise.
Inform the doctor about any symptoms such as fatigue, pallor, or jaundice.
Results are interpreted alongside medical history, symptoms, and other blood tests.

G6PD Test Results

1️⃣ Normal Results

Men & Women: Typically 7–20 U/g Hb.
Interpretation: Sufficient enzyme activity; safe to consume most foods and medications.

2️⃣ Low Results (G6PD Deficiency)

Partial Deficiency: Often in female carriers; enzyme activity below normal; hemolysis may occur with fava beans or certain drugs.
Complete Deficiency: Often in males; very low or absent enzyme activity; risk of severe hemolysis.
Possible Symptoms: Pallor, weakness, fatigue, yellowing of skin/eyes, dark urine.

3️⃣ High Results (Rare)

Usually not a health concern; may be due to temporary factors or technical error.

4️⃣ Factors Affecting Accuracy

Sample collected during a hemolytic episode.
Recent medications or supplements.
Other blood disorders (e.g., sickle cell, thalassemia).

5️⃣ After the Results

For partial or complete deficiency:
- Educate about prohibited foods and medications.
- Conduct family testing if necessary.
- Establish a follow-up plan for children or adults at risk of hemolytic episodes.

Risks and Side Effects of the G6PD Test

1️⃣ Pain or Discomfort from Needle Prick

Infants: Sample from heel; brief discomfort.
Adults: Mild temporary discomfort in the arm.

2️⃣ Bleeding or Bruising

Minor bleeding or small bruise at puncture site, usually controlled with light pressure.

3️⃣ Infection

Very rare; risk minimized by using single-use sterile equipment.

4️⃣ Inaccurate Results

Infants: During severe jaundice or if certain medications are used.
Adults: Some medications (antibiotics, heart meds, antimalarials) may affect results.
Retesting may be necessary to confirm results.

5️⃣ Anxiety or Stress

Infants: Crying is normal; comfort them during sampling.
Adults: Temporary fear or anxiety from needle.

6️⃣ Very Rare Effects

Allergic reactions to reagents in some tests.
Serious complications (severe bleeding, infection) are extremely rare.

⚠️ Important Notes:

The G6PD test is very safe for both adults and infants.
Most risks are mild and temporary.
Consult a doctor immediately if you notice:
- Persistent bleeding
- Severe redness or swelling
- Heat or discharge at the puncture site

Medications That May Affect G6PD Test Results

1️⃣ Drugs that Temporarily Reduce G6PD Activity

May show a false-normal result despite deficiency:

Drug Type	Examples	Potential Effect on Test
Antimalarials	Primaquine, Quinine	Temporarily reduce enzyme activity
Sulfonamide antibiotics	Sulfamethoxazole, Trimethoprim/Sulfa	Temporarily reduce enzyme activity
Nitrofurantoin	Nitrofurantoin	May temporarily lower enzyme levels
Other rare drugs	Certain antifungals	May interfere with enzyme measurement

2️⃣ Drugs That Can Cause Hemolysis in G6PD Deficiency

Do not directly affect enzyme measurement, but may cause inaccurate results if sample taken during hemolysis:

Drug Type	Examples	Notes
Oxidative antimalarials	Primaquine, Quinine	Can trigger red blood cell breakdown
Sulfonamides	Sulfamethoxazole	May cause hemolysis
Other oxidative drugs	Limited categories	Can lead to hemolysis

3️⃣ Drugs That Reduce Nutrient or Enzyme Absorption

Some antacids or stomach medications (rare).
May reduce enzyme production or show lower activity.

4️⃣ Supplements or Foods

Supplements containing peroxides or active oxygen may temporarily affect enzyme activity.
Certain herbs or supplements with strong oxidative compounds.