Glucose-6-Phosphate Dehydrogenase, Quant.

The Glucose-6-Phosphate Dehydrogenase, Quant. test contains 1 test with 1 biomarker.

Brief Description: The Glucose-6-Phosphate Dehydrogenase (G6PD) Quantitative test measures the level of the G6PD enzyme in the blood. G6PD is an essential enzyme involved in the metabolism of glucose in red blood cells. This test helps identify G6PD deficiency, a hereditary condition that affects the enzyme's production, leading to a risk of hemolytic anemia.

Also Known As: G6PD Test, G6PD Enzyme Test, RBC G6PD test, G-6-P-D Test

Collection Method: Blood Draw

Specimen Type: Whole Blood

Test Preparation: No preparation required

When is a Glucose-6-Phosphate Dehydrogenase test ordered?

When a person develops signs and symptoms of hemolytic anemia, G6PD enzyme testing is done. When someone has experienced an episode of elevated RBC destruction but the crisis has passed, testing may be done.

When other lab test findings point to hemolytic anemia, testing may be performed. 

When alternative causes of anemia and jaundice have been eliminated and several weeks have passed since an acute episode, G6PD activity testing is usually recommended.

What does a Glucose-6-Phosphate Dehydrogenase blood test check for?

The enzyme glucose-6-phosphate dehydrogenase is involved in the creation of energy. It is found in all cells, including red blood cells, and aids in the protection of these cells against some hazardous by-products of cellular metabolism. RBCs with a G6PD deficit are more susceptible to splitting apart under specific situations. To assist diagnose a deficit, this test analyzes the quantity of G6PD in RBCs.

G6PD insufficiency is a hereditary condition. When people who have inherited this illness are exposed to a trigger like stress, infection, certain medicines, or another substance, the structure of their red blood cells changes significantly. Heinz bodies are deposits formed by hemoglobin, the life-sustaining, oxygen-transporting protein found in RBCs. When exposed to fava beans, some people have these symptoms, which is known as "favism." RBCs might break apart more easily as a result of these alterations, resulting in a reduction in the quantity of RBCs. Hemolytic anemia occurs when the body is unable to manufacture enough RBCs to replace those that have been destroyed. Symptoms include jaundice, weakness, exhaustion, and/or shortness of breath.

G6PD insufficiency is the most common enzyme deficiency, affecting over 400 million individuals worldwide. It can be found in as many as 10% of African-American men and 20% of African men. People from the Mediterranean and Southeast Asia are also susceptible.

Due to mutations or alterations in the G6PD gene that produce lower enzyme activity, G6PD deficiency is inherited and handed down from parent to kid. G6PD insufficiency has approximately 440 different forms. The G6PD gene is found on the X chromosome, which is inherited from both parents. Because men have only one X and one Y chromosome, the G6PD gene is only found on the X chromosome. If a guy gets the single X chromosome with a mutated gene, he may have G6PD deficiency.

Women inherit two copies of the G6PD gene since they have two X chromosomes. Women with only one mutant gene produce enough G6PD to show no symptoms most of the time, although they may show a minor version of the deficit in stressful settings. A mother can also carry the single altered gene to any male children she has. Women with two defective gene copies, which could lead to G6PD deficiency, are uncommon.

In infants, G6PD deficiency is a prevalent cause of chronic jaundice. This can result in substantial brain damage and mental impairment if left untreated.

The majority of persons with G6PD deficiency can live relatively normal lives, however there is no specific treatment for it other than prevention. They must be cautious and avoid pharmaceuticals like aspirin, phenazopyridine, and rasburicase, as well as antibiotics with "sulf" in the name and dapsone, anti-malarial treatments with "quine" in the name, foods like fava beans, and chemical chemicals like naphthalene. Fava beans, often known as broad beans, are widely farmed in the Mediterranean region. Acute viral and bacterial infections can cause hemolytic anemia and blood acid levels to rise. Individuals should seek a thorough list of these triggers from their healthcare provider. The list on the G6PD Deficiency Favism Association website is a nice place to start.

RBCs are destroyed at a faster rate in hemolytic anemia, and the person affected feels pale and tired as their ability to provide oxygen to their body decreases. Jaundice can be observed in severe cases of RBC breakdown. The majority of these episodes are self-limiting, but if a substantial number of RBCs are lost and the body is unable to replenish them quickly enough, the affected person may require a blood transfusion. If not addressed, this illness can be fatal. Chronic anemia can afflict a small number of people with G6PD deficiency.

Lab tests often ordered with a Glucose-6-Phosphate Dehydrogenase test:

When a G6PD test is ordered, it's often part of a broader evaluation of hemolytic anemia and related conditions. Here are some tests commonly ordered alongside it:

  1. Complete Blood Count (CBC) with Differential:

    • Purpose: To evaluate overall blood health, including red and white blood cells, and platelets.
    • Why Is It Ordered: To assess for signs of anemia (such as decreased hemoglobin and hematocrit) and to evaluate the shape and size of red blood cells, which can be affected in hemolytic anemia.
  2. Reticulocyte Count:

    • Purpose: To measure the number of young red blood cells in the blood.
    • Why Is It Ordered: An increased reticulocyte count can indicate that the body is producing more red blood cells to compensate for those being destroyed in hemolytic anemia.
  3. Bilirubin (Total and Direct):

    • Purpose: To measure the level of bilirubin, a byproduct of red blood cell breakdown.
    • Why Is It Ordered: Elevated levels of bilirubin, especially unconjugated bilirubin, can occur in hemolytic anemia.
  4. Lactate Dehydrogenase (LDH):

    • Purpose: To measure LDH, an enzyme that can be elevated in hemolysis.
    • Why Is It Ordered: To assess for increased red blood cell destruction.
  5. Haptoglobin:

    • Purpose: To measure the level of haptoglobin, a protein that binds free hemoglobin.
    • Why Is It Ordered: Low haptoglobin levels can be a sign of hemolytic anemia.
  6. Direct Antiglobulin Test (DAT or Coombs Test):

    • Purpose: To detect antibodies that are attached to the surface of red blood cells.
    • Why Is It Ordered: To differentiate between autoimmune causes of hemolysis and other types, such as G6PD deficiency.
  7. Iron Studies:

    • Purpose: To evaluate body iron stores and iron utilization.
    • Why Is It Ordered: To rule out iron deficiency anemia and assess iron levels, which can be affected in chronic hemolysis.

These tests, when ordered alongside a G6PD test, provide a comprehensive view of the causes and effects of hemolysis and anemia. They are crucial for diagnosing G6PD deficiency, understanding the severity of hemolytic anemia, and guiding appropriate treatment and management, including the avoidance of triggers that can precipitate hemolysis in G6PD-deficient individuals. The specific combination of tests will depend on the individual’s symptoms, medical history, and initial test results.

Conditions where a Glucose-6-Phosphate Dehydrogenase test is recommended:

The primary condition that would require a G6PD Quantitative test is G6PD deficiency, a genetic disorder that affects the G6PD enzyme's function in red blood cells. G6PD deficiency can lead to hemolytic anemia, especially when exposed to certain triggers like specific medications, infections, or fava beans.

How does my health care provider use a Glucose-6-Phosphate Dehydrogenase test?

The enzyme assay for glucose-6-phosphate dehydrogenase is used to screen for and diagnose G6PD deficiency. It could be used to screen children who were born with unexplained chronic jaundice. Currently, babies are not routinely tested for G6PD deficiency; however, this depends on the state that offers the service. According to the National Newborn Screening and Genetics Resource Center, two states, Pennsylvania and the District of Columbia, offer G6PD testing as part of their newborn screening panel as of November 2014.

G6PD is an enzyme present in all cells, including red blood cells, that protects them against hazardous by-products of cellular metabolism. RBCs with a G6PD deficit are more susceptible to splitting apart under specific situations.

People of any age who have experienced unexplained episodes of hemolytic anemia, jaundice, or dark urine may benefit from G6PD testing to assist establish a diagnosis. G6PD deficiency may be suspected if the person had a recent viral or bacterial illness or was exposed to a recognized trigger, followed by a hemolytic event.

G6PD testing may be repeated on occasion to validate initial findings. A simple qualitative test is usually used in screening tests to determine if a person has a high amount of G6PD in his or her cells. A quantitative test will be used to determine the actual quantity of enzyme activity during confirmation testing.

G6PD levels are normal in newly generated cells in the most prevalent form of G6PD deficiency seen in people of African heritage, but decline by up to 75% as RBCs age. As a result, testing should be delayed for several weeks after a hemolytic episode has passed. The older, more fragile G6PD-deficient RBCs are often killed during the episode, leaving the newer, less deficient cells to be tested, potentially hiding a G6PD deficiency.

Although genetic testing is not commonly performed, it can be requested as a follow-up to an enzyme test that suggests a deficiency in order to discover which G6PD mutations are present. There are currently around 440 G6PD gene variants that can produce varied degrees of deficiency based on the mutation and the specific person. Some mutations have no effect on the activity of the G6PD enzyme. The G6PD mutations have been divided into five groups by the World Health Organization, depending on the enzyme levels and their influence on the affected person's health. During testing, however, only the most prevalent G6PD mutations are discovered. If a certain mutation is known to exist in a family line, tests to detect that mutation can be performed.

What do my Glucose-6-Phosphate Dehydrogenase test results mean?

A deficit is indicated by a low level of G6PD enzyme. When exposed to a trigger, an affected person is more likely to develop symptoms. However, the findings cannot be utilized to forecast how an affected individual will react in a specific situation. Symptom severity varies from person to person and from episode to episode.

If a male has a normal G6PD enzyme level, he is unlikely to have a deficit, and if anemia is present, it is most likely due to another cause. If the test was done during a bout of hemolytic anemia, it should be redone several weeks later once the RBC population has replenished and matured.

Carriers, who have one mutant and one normal gene copy, will have some G6PD-deficient RBCs and others that are not. G6PD levels in these women are normally normal or near normal, and they rarely exhibit symptoms. A carrier will have a normal or low normal G6PD level, therefore they may not be discovered by G6PD screening, but they will be detected by a G6PD confirmation test, which measures the overall quantity of enzyme present in the cells. It's worth noting that a rare female with two defective gene copies will almost certainly have a large drop in G6PD levels.

Most Common Questions About the Glucose-6-Phosphate Dehydrogenase test:

Understanding the Glucose-6-Phosphate Dehydrogenase Quantitative Test

What is the Glucose-6-Phosphate Dehydrogenase (G6PD) quantitative test?

The G6PD quantitative test measures the amount of the G6PD enzyme in your blood. G6PD is crucial for the health of red blood cells, and a deficiency can lead to hemolytic anemia.

Why is the G6PD quantitative test important?

The G6PD test is important because it helps identify individuals who have G6PD deficiency, a genetic condition that can lead to the breakdown of red blood cells.

In what circumstances might a doctor recommend a G6PD test?

A doctor might recommend a G6PD test if a patient is exhibiting signs of hemolytic anemia or if there's a history of unexplained jaundice or neonatal jaundice. It is also used prior to prescribing medications known to cause hemolysis in individuals with G6PD deficiency.

Interpreting G6PD Quantitative Test Results

What do the results of a G6PD quantitative test indicate?

Low levels of G6PD activity suggest a G6PD deficiency. This can cause red blood cells to break down prematurely, leading to hemolytic anemia.

What does a normal G6PD level mean?

A normal G6PD level indicates that there's enough G6PD enzyme in the red blood cells, and the person is not likely to have G6PD deficiency.

Can G6PD test results be influenced by other factors?

Yes, factors such as recent blood transfusion or current hemolysis can affect the G6PD test results.

What is the relationship between G6PD levels and severity of symptoms?

Severity of G6PD deficiency symptoms can vary significantly and isn't always directly correlated with the specific enzyme levels measured in the test.

The G6PD Test and Specific Health Conditions

How is the G6PD test used in the context of hemolytic anemia?

G6PD test can diagnose G6PD deficiency, one of the causes of hemolytic anemia.

Can the G6PD test help diagnose jaundice in newborns?

Yes, G6PD deficiency can cause severe jaundice in newborns, so the test may be used in diagnosis if there's a suspicion of this condition.

Can the G6PD test help manage sickle cell disease?

Yes, G6PD deficiency can coexist with sickle cell disease. Knowing if a patient with sickle cell disease also has G6PD deficiency is important for management.

What is the relationship between the G6PD test and favism?

Favism is a condition that causes hemolytic anemia after eating fava beans or inhaling pollen from the fava plant. This condition is associated with G6PD deficiency, so the test can help in diagnosing favism.

The G6PD Test and Medications

Can the G6PD test guide the use of certain medications?

Yes, certain medications can trigger hemolysis in individuals with G6PD deficiency. This test can help determine if an individual can safely take these medications.

Can the G6PD test help in managing potential side effects of antimalarial drugs?

Yes, some antimalarial drugs can cause hemolytic anemia in individuals with G6PD deficiency. The G6PD test can guide safe prescribing of these medications.

Can the G6PD test prevent complications from certain antibiotics?

Certain antibiotics can cause hemolysis in people with G6PD deficiency. Testing for G6PD levels can help determine if these antibiotics can be safely prescribed.

The G6PD Test in Different Populations

How is the G6PD test used in newborn screening?

In some regions, G6PD testing is part of newborn screening due to the risk of severe neonatal jaundice.

How does the G6PD test apply to individuals of Mediterranean, African or Asian descent?

G6PD deficiency is more common in individuals of Mediterranean, African or Asian descent. The G6PD test is especially relevant in these populations.

Can the G6PD test be used in pregnant women?

Yes, the G6PD test can be used in pregnant women, especially those with a family history of G6PD deficiency or with previous newborns with severe jaundice.

The G6PD Test and Environmental Factors

Can the G6PD test help in managing risks associated with exposure to certain chemicals?

Yes, exposure to certain chemicals like naphthalene (found in mothballs) can trigger hemolysis in people with G6PD deficiency. Knowing an individual's G6PD status can help manage these risks.

How does diet interact with the G6PD test?

Certain foods, notably fava beans, can trigger hemolysis in individuals with G6PD deficiency. The G6PD test can guide dietary recommendations.

Can the G6PD test be used in cases of unexplained hemolysis after exposure to a new environment?

Yes, unexplained hemolysis could be due to G6PD deficiency being triggered by an environmental factor.

The G6PD Test and Other Diagnostic Tools

How does the G6PD test relate to genetic testing?

The G6PD test measures enzyme activity, while genetic testing can identify mutations in the G6PD gene. Both tests can help diagnose G6PD deficiency.

Can the G6PD test be used alongside other tests for hemolytic anemia?

Yes, the G6PD test is often used alongside other tests, like complete blood count, reticulocyte count, and haptoglobin, to diagnose hemolytic anemia.

How is the G6PD test used in conjunction with a direct antiglobulin test (DAT)?

If a patient has hemolytic anemia and the DAT is negative, a G6PD test might be performed to check for G6PD deficiency.

Can the G6PD test be used alongside tests for other hemolytic conditions?

Yes, in the context of unexplained hemolytic anemia, a variety of tests including the G6PD test may be performed.

Is the G6PD test a part of general blood testing panels?

No, the G6PD test is not typically included in general blood testing panels. It's usually ordered when there is a specific clinical suspicion of G6PD deficiency.

We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.

The following is a list of what is included in the item above. Click the test(s) below to view what biomarkers are measured along with an explanation of what the biomarker is measuring.

Also known as: G-6-PD (B), Glucose 6 Phosphate, Glucose6Phosphate Dehydrogenase Quant

Glucose-6-Phosphate

A blood glucose test measures the amount of a sugar called glucose in a sample of your blood. Glucose is a major source of energy for most cells of the body, including those in the brain. The hormones insulin and glucagon help control blood glucose levels.
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