Glucose-6-Phosphate Dehydrogenase (G6PD) test

What is a Glucose-6-Phosphate Dehydrogenase test?

Glucose-6-phosphate dehydrogenase (G6PD) is an enzyme that is found in every cell of the body and it plays an important role in cellular metabolism. Another function of the enzyme is to protect the red blood cells from oxidation.

In case of any deficiency of the enzyme, the RBCs become more vulnerable to oxidative damage and can even break apart in certain conditions. This phenomenon is also called hemolysis. The test for G6PD is a blood test that is used to determine the deficiency of the enzyme in an individual. The deficiency is often triggered by genetics and mostly occurs in males. It has been estimated that around 400 million people in the world suffer from a deficiency of this enzyme.

A person with an insufficient amount of the enzyme can develop hemolytic anemia due to an inadequate quantity of the red blood cells. In many cases, hemolytic anemia is triggered by bacterial or viral infections or by certain drugs. In most people, the condition remains undetected as it does not have any specific external symptoms. In the case of kids and new-borns, the condition can develop into mild to serious forms of jaundice.

In some cases, the red blood cells deficient in the enzyme are sensitive to certain medicines, foods, and infections. Such a trigger can cause a rapid loss of RBCs and it is termed as a hemolytic crisis. Among the various triggers, some major ones are mentioned below.

– Illness related to bacterial and viral infections
– A few specific painkillers and fever-lowering drugs
– Some antibiotics
– Some antimalarial drugs
– Consumption of fava beans also called broad beans. Inhalation of pollen from the fava plant can also act as a trigger.
– In some cases, naphthalene, a chemical found in mothballs and moth crystals can also act as a trigger.

The enzyme also assists in the conversion of glucose into Ribose-5-phosphate, which is an important component of nucleotides. The nucleotides are the building blocks of DNA and also of the RNA. In the process, a special molecule called NADPH is formed which plays an important role in the prevention of oxidative damage of the cells. Since RBCs lack any other NADPH-producing enzymes, they are the most affected when there is a deficiency of G6PD.

Why do I need to undergo a Glucose-6-Phosphate Dehydrogenase test?

In many cases, this test is ordered when the doctor has ruled out any other reasons for anemia or jaundice. The deficiency can be related to a few symptoms mentioned under.

– An enlarged spleen
– Fainting
– Fatigue or dizziness
– Rapid heart rate
– Red or brown urine
– Shortness of breath or fast breathing rate.
– Presence of Heinz bodies inside the RBCs
– Increased count of reticulocytes.

The doctor also takes into consideration the medical history of the patient and the drugs that have been consumed before ordering the test. A new-born with a deficiency of the hormone can show symptoms of jaundice including yellow colored urine, pale stools, and increasing bilirubin levels.

How is the glucose-6-Phosphate Dehydrogenase test performed?

The test is performed by collecting a blood sample from a vein through a process known as a venipuncture. In this process, a needle is inserted into a vein to draw the required volume of blood. The process is simple and short and it involves the following steps.

– An elastic band or a cuff is tied in the upper arm to make the veins swell with blood, thus making them more visible. The collection site is generally around the elbow region and the healthcare practitioner disinfects the area where the needle will be inserted to clear any microorganisms. In some cases, blood may also be collected from the back of the hand.

– A needle is inserted into the vein and the required volume of blood is drawn through it in an attached tube. A prick or sting is felt when the needle is inserted. It can be accompanied by a slight throbbing which goes away with time.

– The band on the arm is loosened and the needle is then withdrawn. The pressure is applied to the site through a gauze or a cotton piece to prevent any excessive bleeding. The spot is then covered with a sterile bandage and the blood sample is sent to the laboratory for testing.

-The entire process is safe and is generally concluded within a few minutes. Since the size of the veins can differ from one person to the other, multiple punctures may be needed for some patients, before the right vein is found. Some patients might feel dizzy or lightheaded after the collection and may need proper care.

– Any pain or mild bruising in and around the collection site is generally cured within a few days. Chances of infection or excessive bleeding from the site are rare but might happen in exceptional cases. In such cases, the necessary treatment will be needed.

What is the price for a Glucose-6-Phosphate Dehydrogenase test in India? 

The cost of the test in India ranges from Rs 400 to Rs 1800 depending on the location and the facilities of the test center.
 

When will I get the test results?

The test results are generally delivered within 24 to 72 hours depending on the laboratory.

What is the normal range for a Glucose-6-Phosphate Dehydrogenase test?

The test results depend on gender, age, medical history and also on the laboratory that is conducting the process. The doctor can determine the exact significance of the results keeping all the factors in mind. In general, a normal result for the enzyme for adults is 5.5 to 20.5 units/gram of hemoglobin.

What do the results mean?

The results may not bring about the same conditions and symptoms in everyone and the response to a deficiency varies from one person to another. The following conclusions can be drawn from the tests.

– A normal result indicates that there is no deficiency in the system.

– A value of 10 % of the normal levels indicates a severe deficiency and chronic hemolytic anemia.

– In some cases, a severe deficiency can also be marked by intermittent anemia.

– For those within 10% to 60% range, the deficiency is moderate and can be related to particular infections and medications.

– Additional follow-up tests can be ordered to look into the details of the issue in the doctor suspects some complications.

Do I need to fast for the Glucose-6-Phosphate Dehydrogenase test?

Fasting or dietary restrictions are not necessary for the test.

What else do I need to know before I appear for a Glucose-6-Phosphate Dehydrogenase test?

The following points will provide a detailed insight into the various aspects of the test.

– Any male with a family history of the disease more likely to be deficient of the enzyme. The deficiency is also prevalent in African-Americans and in people of southeast Asia.

– Before the test, it is important to inform the doctor about any medication that you might be consuming. As mentioned earlier, certain medicines can have an impact on the test results and should be consumed with the doctor’s advice.

– The treatment for the deficiency mainly involves removing the trigger that is causing symptoms. In most cases, the deficiency is automatically cured once the trigger is removed. When it has been triggered by a particular infection, treatment of that infection is necessary. Managing the condition involves avoiding these triggers and also avoiding stress in daily life.

– In the case of hemolytic anemia, more aggressive treatments like oxygen therapy or blood transfusion to replenish the RBCs may be necessary.

– The children with the condition can live healthy, symptom-free lives when the condition is diagnosed at an early stage and the right steps are taken.

– The prevalence of this deficiency is related to the geographical belt that is affected by malaria. Hence certain theories state that the deficiency offers partial protection against malaria infection.

– In case a G6PD genetic mutation is detected, the patient is likely to experience various levels of symptoms throughout his or her life.

Can pregnant women undergo a Glucose-6-Phosphate Dehydrogenase test?

Pregnant women can undergo the test without any restrictions.

Is Glucose-6-Phosphate Dehydrogenase test possible for new-born babies?

The test is possible for new-born babies as advised by the doctor.