G6PD

Other names: Glucose-6-Phosphate Dehydrogenase; G-6-PD

Glucose-6-Phosphate Dehydrogenase (G6PD) is an enzyme, which helps to protect the red blood cells from oxidation. If levels of G6PD are too low, there is a higher risk of the red blood cells suffering from oxidative damage; if the red blood cells are exposed to oxidising agents, it causes the structure of the cell to alter and results in the red blood cell being broken down. G6PD deficiency is the most common form of enzyme deficiency in the world; it is estimated that 20% of the African population suffer from this deficiency.

When is the test used?

The test may be used to try and find a cause for chronic jaundice for newborn babies, if no other cause has been identified. The test may also be used on patients who are suspected of having haemolytic anaemia.

The test is usually ordered for patients with symptoms of anaemia, including tiredness, pale skin, weakness, jaundice and a general lack of energy. The test must be carried out once the acute episode is over and not while the patient is recovering from a haemolytic episode.

How is the test carried out?

The test is performed by taking a sample of the patient’s blood from a vein in the arm; a needle is inserted into the vein and the blood is drawn out and collected in a syringe. Once the sample has been collected, it will be bottled, labelled and sent away for analysis.

What do the test results show?

If test results are normal, this indicates that the patient does not have a G6PD deficiency.

If levels are lower than normal, this may mean the individual is at risk of developing symptoms if they are exposed to oxidative stress.

If genetic testing reveals that a patient has a G6PD mutation, this will usually mean that they have a deficiency of G6PD; some people may have severe symptoms, while others may never suffer any symptoms.

If a parent has a mutation, they may pass this onto their children: if the father is affected, the daughters will be carriers but the sons will be normal. A heterozygous female then has a 50% chance of passing the mutation onto their children; the sons will be normal, while the daughters will be carriers. It is extremely rare for a female to be homozygous (two copies of the mutated gene); however, if this is the case, her sons will be affected and her daughters will be carriers.

Specific Blood Tests

Blood Test Guide

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