Test Detail
Interpreting Results

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Written by
Dr. Betina Chandolia
BDS, MDS - Oral Pathology and Microbiology
Reviewed by
Dr. Lalit Mohan Gupta
MBBS, MD - Microbiology
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Glucose 6 Phosphate Dehydrogenase (G6PD Quantitative)

(G6PD Quan.)
You need to provide
This test is for
Male, Female
Test Preparation
  1. No special preparation required


What is G6PD Quan.?

Glucose-6-phosphate dehydrogenase (G6PD) is an enzyme found in all the cells of the body and is involved in the production of energy. It protects the red blood cells from the by-products produced during metabolism. A deficiency of this enzyme makes the red blood cells (RBCs) more prone to breaking apart under certain conditions. The G6PD Quantitative Test measures the levels of the enzyme G6PD in blood.

Why is G6PD Quan. done?

The G6PD Quantitative Test is performed:

·         To determine G6PD deficiency as the cause of hemolytic anemia

What does G6PD Quan. Measure?

Glucose-6-phosphate dehydrogenase is an enzyme present in all the cells of the body. G6PD serves to provide energy to the cells. It protects the red blood cells from the toxic by-products formed during metabolism.

G6PD deficiency creates an oxidative environment in the body which can cause large-scale breakdown of RBCs (hemolysis). This breakdown could be caused due to certain triggers such as bacterial infections, consuming fava beans, certain medicines, etc. Hemolysis is more common in the older cells as the amount of G6PD enzyme decreases with the age of RBCs.

In case of exposure to any trigger, G6PD-deficient RBCs start depositing hemoglobin in them. This leads to the formation of small granules called Heinz bodies. These RBCs containing Heinz bodies are usually removed from the blood circulation in the spleen, but in severe cases may breakdown in blood circulation itself. The body’s inability to compensate for the large-scale destruction of RBCs causes hemolytic anemia (anemia due to the breakdown of RBCs). Hemolytic anemia causes symptoms such as yellowing of skin and eyes (jaundice), weakness and difficulty in breathing.

In spite of being an evolutionary disadvantage, G6PD deficiency is prevalent worldwide in a number of different forms. G6PD deficiency is very commonly observed in malaria-prevalent regions, such as Africa, South East Asia, the Middle East and the Mediterranean. The only possible reason for this is that a person affected with the deficiency of G6PD is protected from malaria. Since malarial parasites divide and grow in the RBCs, it is considered that the rapid destruction of RBCs in the spleen removes malarial parasites quickly from the system. Also, oxidative stress has been seen to be lethal to these parasites, making them unable to survive in the oxidative body environment in G6PD deficient individuals.

Interpreting G6PD Quan. results


Normal range: 4.60 - 13.50 units/g Hb (hemoglobin)

The amount of G6PD deficiency does not directly correlate with the severity of symptoms that appear.

Those with less than 10% of the normal G6PD amount are considered severely deficient and with chronic hemolytic anemia.

Those with 10% to 60% of the normal G6PD amount are considered moderately deficient and may undergo episodes of hemolytic anemia in response to triggers.

Answers to Patient Concerns & Frequently Asked Questions (FAQs) about G6PD Quan.

Frequently Asked Questions about Glucose 6 Phosphate Dehydrogenase (G6PD Quantitative)

Q. How is this test performed?
This test is performed on a blood sample. A syringe with a fine needle is used to withdraw blood from a blood vessel in your arm. The healthcare provider will tie an elastic band around your arm to make the blood vessels swell with blood. This makes it easier to withdraw blood. You may be asked to tightly clench your fist. Once the veins are clearly visible, the area is cleaned with an antiseptic solution and then the needle is inserted into the blood vessel to collect the sample. You will feel a tiny pinprick during the procedure. Blood sample once collected will then be sent to the laboratory.
Q. Is there any risk associated with this test?
There is no risk associated with the test. However, since this test involves a needle prick to withdraw the blood sample, in very rare cases, a patient may experience increased bleeding, hematoma formation (blood collection under the skin), bruising or infection at the site of needle prick.
Q. Is there any preparation required before the G6PD Quantitative Test?
The test is not to be performed immediately after a blood transfusion or hemolytic episode. Inform the doctor about any medications you may be taking. No other preparations are required unless specified by your doctor.
Q. What other tests can be prescribed by your doctor in case the results of G6PD Quantitative Test are not normal?
Other tests that may be prescribed upon appearance of abnormal result in the G6PD Quantitative Test include: · Complete Blood Count (CBC) · Reticulocyte Count · Blood Smear Test for Heinz Bodies · Liver Function Tests · Kidney Function Tests · Lactate Dehydrogenase Test · Haptoglobin (decreased in hemolysis) · Coomb’s Test
Q. What are the triggers that may start a hemolytic episode in G6PD-deficient individuals?
Common triggers that may lead to the start of hemolytic episode are: · Ingestion of fava beans · Inhaling pollen of fava plant · Bacterial infections · Viral infections · Napthalene (found in moth balls) · Certain medicines like aspirin · Certain antibiotics like isoniazid · Certain antimalarial medicines like quinine · Certain sulfa medications like sulfamethoxazole
Q. Why is G6PD deficiency more prevalent in males than in females?
Genes are short sequences of codes in the genetic material (DNA in humans) that express certain characters called traits. Human beings have two copies of each gene. One copy is present on chromosome inherited from the father and the other copy is present on the chromosome inherited from the mother. If both the chromosomes have the same copies of a gene (either both expressing the trait, or neither expressing it), the condition is called homozygous. Whereas, if the chromosomes have two alternate copies of the same gene (one expressing the trait and the other does not), the condition is called heterozygous. A dominant trait is one that can be expressed in both homozygous and heterozygous conditions, but a recessive trait can only be expressed in a homozygous condition. G6PD deficiency is an X-linked recessive trait. This means that the G6PD gene is located on the X chromosome and deficiency is expressed as a recessive condition. Males have an X chromosome and a Y chromosome in their cells. This ensures that if the recessive trait of G6PD deficiency is present in the X chromosome of a male, it will always be expressed and cause G6PD deficiency. However, females have two copies of the X chromosome in their cells. Thus, G6PD deficiency is usually expressed in females only if both the X chromosome copies have defective G6PD genes (homozygous), and not if only one defective copy is present (heterozygous). This is the reason that G6PD deficiency is a trait more prevalent in males than in females. Females who have only a single defective copy of the X chromosome are called carriers. This means that while they themselves do not express G6PD deficiency, they may transfer the trait to their male child.
Q. What are the symptoms of G6PD deficieny?
G6PD deficiency is usually asymptomatic. Symptoms of G6PD deficiency can appear in response to certain triggers and may include: · Yellowing of the skin and whites of the eyes · Dark colored urine · Rapid heartbeat · Fatigue · Shortness of breath · Diabetic ketoacidosis · Acute kidney failure · Neonatal jaundice (jaundice in newborns indicated by abnormally high levels of bilirubin that do not fall after more than two weeks)
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