G6PD (glucose-6-phosphate dehydrogenase) is an enzyme that helps cells process glucose and protects red blood cells from harmful chemical buildup. It produces NADPH, a molecule that supports the cell’s natural defenses against oxidative damage. This protection is important because red blood cells carry oxygen and are especially vulnerable to such damage. When G6PD activity is too low, red blood cells can break down earlier than they should.
How does G6PD protect the body?
G6PD is an enzyme found in almost all types of cells. It supports a series of chemical reactions involved in processing glucose, a sugar that the body uses for energy. One important result of these reactions is the production of a molecule called nicotinamide adenine dinucleotide phosphate (NADPH), which helps cells maintain their natural protective systems. According to MedlinePlus Genetics, this process is particularly important in red blood cells because they have limited ways to produce NADPH.
NADPH helps cells control potentially harmful molecules called reactive oxygen species. These molecules form naturally during normal cell activity, but excessive amounts can damage cell structures. The body needs a balance between producing these molecules and protecting cells from their effects. G6PD contributes to that balance by supporting the chemical reactions that help keep reactive oxygen species from reaching harmful levels.
Why is G6PD important for red blood cells?
Red blood cells carry oxygen from the lungs to the body's tissues. They constantly work in an oxygen-rich environment and are exposed to substances that can cause oxidative damage. Unlike many other cells, mature red blood cells cannot replace damaged components by making new proteins in the usual way. They therefore depend heavily on protective mechanisms that preserve their function and structure.
G6PD supports these defenses by helping red blood cells maintain the conditions they need to survive. When this protection works properly, the cells can continue transporting oxygen until they reach the end of their normal lifespan. If the protective system is inadequate, harmful molecules can damage the cells and cause them to break down prematurely. This process is known as hemolysis.
What happens when G6PD activity is too low?
G6PD deficiency is an inherited condition in which the body produces too little functional G6PD or the enzyme does not work as effectively as it should. Genetic changes in the G6PD gene can affect how much enzyme is produced or how well it functions. The resulting reduction in protection makes red blood cells more vulnerable to oxidative damage. MedlinePlus Genetics explains that this damage can cause red blood cells to be destroyed faster than the body can replace them.
When red blood cells are lost faster than they are replaced, a person may develop hemolytic anemia. This condition means that there are not enough healthy red blood cells to carry oxygen effectively. The effects can include tiredness, pale skin, yellowing of the skin or eyes (jaundice), dark urine, a rapid heartbeat, or shortness of breath. These are examples of symptoms that can occur during red blood cell breakdown, not a checklist for identifying G6PD deficiency.
What can trigger red blood cell breakdown in G6PD deficiency?
Many people with G6PD deficiency remain well and do not experience noticeable problems in everyday life. However, certain exposures can increase oxidative stress and lead to red blood cell damage. According to the MedlinePlus Medical Encyclopedia, common triggers include infections, certain medicines, and fava beans, also known as broad beans.
The specific medicines that may cause problems depend on the drug and the person's circumstances. Some medicines used to treat infections or malaria can be unsafe for people with particular levels of G6PD activity. People who have been diagnosed with G6PD deficiency should tell their healthcare professionals and pharmacists about it before starting a medicine or supplement. They should not stop a prescribed medicine without professional guidance.
An infection can also trigger red blood cell breakdown, even when a person has not taken a new medicine or eaten fava beans. This is one reason a clinician may consider G6PD deficiency when evaluating unexplained anemia or jaundice following an illness. The timing of symptoms, medication history, examination findings, and blood test results all help guide the assessment.
Can G6PD deficiency affect newborns?
Yes. G6PD deficiency can be relevant shortly after birth because affected newborns may develop jaundice, which causes the skin and whites of the eyes to appear yellow. Jaundice occurs when bilirubin, a substance produced during the breakdown of red blood cells, builds up in the blood. Newborns already need careful monitoring for jaundice, and G6PD deficiency can increase the risk of a significant rise in bilirubin.
University College London Hospitals NHS Foundation Trust explains that some newborns with G6PD deficiency may need treatment for jaundice, including phototherapy, which uses special light to help the body remove bilirubin. Jaundice in a newborn should be assessed promptly by a healthcare professional, particularly if it appears during the first day of life, worsens, or is accompanied by poor feeding or unusual sleepiness.
How do healthcare professionals check G6PD activity?
A G6PD blood test measures the activity of the enzyme in red blood cells. It may be recommended when a healthcare professional suspects G6PD deficiency because of symptoms, family history, newborn jaundice, or an episode of unexplained red blood cell destruction. The result helps establish whether enzyme activity is lower than expected and can guide decisions about medication safety and follow-up.
According to MedlinePlus Medical Test, the test uses a blood sample to check for G6PD deficiency. Other investigations may be needed when red blood cell breakdown is suspected, depending on the clinical situation. Importantly, the timing of testing can affect interpretation: enzyme activity may appear temporarily normal during or shortly after an episode of hemolysis because the remaining red blood cells include a higher proportion of younger cells. A healthcare professional may recommend repeat testing when appropriate.
G6PD testing is not the same as a standard red blood cell count. A routine blood count measures features such as the number of red blood cells and the amount of hemoglobin, whereas a G6PD test evaluates the activity of a particular enzyme. Healthcare professionals interpret these results alongside the person's medical history and other findings.
What does G6PD mean for everyday health?
G6PD is a normal and important part of the body's cellular protection system. Its role is especially significant in red blood cells, where it helps maintain defenses against oxidative damage. Having adequate enzyme activity supports the normal survival of these cells, while inherited deficiency can make them more vulnerable to certain illnesses, foods, and medicines.
For someone with known G6PD deficiency, understanding the condition mainly means knowing which medicines and exposures need to be reviewed with a healthcare professional. With appropriate guidance and awareness of relevant triggers, many people with the condition remain healthy and manage their daily activities without ongoing problems. New or concerning symptoms that could indicate red blood cell breakdown, such as dark urine, jaundice, marked weakness, or breathing difficulty, warrant prompt medical assessment.