The Biomarker Handbook is a curated series that seeks to provide readers with insights on each biomarker we cover in our blood test packages and its relation to our body.
G6PD stands for glucose-6-phosphate dehydrogenase and it is a key enzyme responsible for energy production. It also indirectly protects the body cells (including red blood cells, RBC) from oxidative damage.
G6PD Deficiency – The Condition
In presence of G6PD deficiency, the RBCs of the affected individual will be susceptible to oxidative damage. This RBC destruction is usually brought on by certain lifestyle and disease triggers. When triggered, RBCs break down easily (haemolysis) leading to anaemia and other symptoms.
G6PD deficiency is the most common enzyme disorder in humans with approximately 400 million people affected worldwide. The prevalence is particularly high in Sub-Saharan Africa, the Middle East, and Southeast Asia.
How Does One Develop G6PD Deficiency?
It is an inherited disorder, transmitted from parent to child. It is X-linked recessive, meaning that the X chromosome carries the G6PD gene and that men (who have only one X-chromosome) will develop G6PD deficiency if they inherit the mutated gene. However, women (with two X-chromosomes) can be carriers with one defective gene or develop the condition with two defective genes. This is why the disease is seen more commonly in men than women.
Screening for G6PD Deficiency
Although there is no cure for this condition, screening for G6PD deficiency is important as it can allow the affected individual to take precautions to avoid the triggers and live a normal and healthy life. It also allows the affected individual to understand how the condition might affect his or her offspring.
Moreover, the condition can prove fatal in newborns due to development of kernicterus. Hence, screening neonates is extremely important, particularly those with unexplained persistent jaundice. If available in your region, neonatal screening should be carried out within 1-2 days of birth.
Most adults with G6PD deficiency are asymptomatic. However, the condition should be suspected in any individual with unexplained haemolytic anaemia, especially if a trigger preceded the episode.
Signs and Symptoms to Watch Out For
Screening in adults should be carried out when presenting with haemolytic anaemia (anaemia due to RBC breakdown). You may experience these signs and symptoms of haemolytic anaemia:
- Weakness and tiredness
- Pallor (pale skin)
- Shortness of breath on minimal exertion
- Increased heart rate
- Enlarged spleen
- Dark-coloured urine
In addition to these, blood investigations might show raised levels of bilirubin, a decrease in RBC count, the presence of haemoglobin in urine, and Heinz bodies on the blood smear.
How is the Test Carried Out? What is the Test?
Testing involves the collection of a blood sample from a vein the arm of adults, or by heel prick in babies. The collected blood is subjected to testing and the results available in a few days.
No preparation is needed for the test. However, a recent haemolytic episode might interfere with the test result and hence, you must inform your doctor of exposure to any triggers in the few days before the test. Also, if you have received a blood transfusion, wait for a few days before testing as the donor RBCs might mask the deficiency.
The G6PD screening test looks at the G6PD activity in your blood cells, and if the result is normal, then you do NOT have G6PD deficiency. People with G6PD deficiency will have an abnormal result, and your doctor will follow this up with a quantitative testing of G6PD to see how severe the deficiency is (usually less than 10% of the normal value means that you have sever G6PD deficiency and chronic haemolytic anaemia).
Prompt treatment is needed during the acute haemolytic episodes. The key step in management is the removal of the precipitating factor or event that led to acute haemolysis.
This should be followed by correction of anaemia. Folic acid and iron supplementation have also proven useful. Fortunately, most episodes are self-limiting once the triggering agent is removed. In severe cases, a blood transfusion might be needed.
Symptomatic newborn babies with G6PD deficiency with neonatal jaundice require phototherapy, and some serious cases of neonatal jaundice might require exchange transfusion.
Living With G6PD Deficiency
Most people with G6PD are usually asymptomatic and rarely require any treatment. Rarely, a severe haemolytic episode might lead to complications such as kidney failure, liver failure, or death. Hence, it is important that you avoid certain medications and chemicals which can trigger an acute haemolytic episode. Common triggers include:
- Drugs such as chloroquine, primaquine, aspirin, NSAIDs (non-steroidal anti-inflammatories), dapsone, sulfonamides, ciprofloxacin, nitrofurantoin.
- Exposure to naphthalene (moth balls)
- Food such as fava beans, blueberries, and soy products
- Exposure to henna (black or red Egyptian type) used in tattoos and dyes
- Acute bacterial and viral infections
It is also important to consider genetic counselling if you are planning a family, to understand the risks and implications of passing on the condition to your future children.
If you want to find out more about G6PD and how you can live with a deficiency, take a look at our lifestyle article here!
Interested in other biomarkers? Check out the rest of The Biomarker Handbook.
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