What are the other Names for this Test? (Equivalent Terms)
- G-6-PD Test
- G6PD (Glucose-6-Phosphate Dehydrogenase) Test
- RBC G6PD Test
What is Glucose-6-Phosphate Dehydrogenase Test? (Background Information)
- Glucose-6 phosphate dehydrogenase (G6PD) is a cellular enzyme (a substance that acts as a catalyst for chemical reactions) that is needed to obtain energy from glucose molecules. It is present in all the cells, including the red blood cells
- Certain drugs, food stuffs, or infections, have a tendency to cause “oxidative damage” to cells. This is prevented by a cellular mechanism that relies on the by-product of the glucose-6 phosphate dehydrogenase catalyzed reaction. Hence, a deficiency of G6PD, leads to oxidative damage
- In the RBCs, there is denaturation of the hemoglobin protein, as well as membrane damage, ultimately leading to cellular destruction
- A G6PD Test is done to check the levels of the enzyme, in order to detect any possible enzyme deficiency. Such a deficiency is inherited as an X-linked recessive disorder. The ‘bad’ gene copy is present on the X chromosome; hence, a male with one bad gene will have an enzyme deficiency, while a female would need two abnormal copies to be enzyme deficient
What are the Clinical Indications for performing the Glucose-6-Phosphate Dehydrogenase Test?
An individual with G6PD deficiency may have episodes of hemolysis (destruction of red blood cells) on exposure to certain drugs, food stuffs, infections, or even stress. This may produce symptoms, such as:
- Racing heartbeat
- Reddish urine
G6PD levels may then be checked to investigate the likely cause of hemolysis, especially in individuals with multiple such episodes and also in the setting of hemolysis, with a likely preceding trigger. G6PD Testing may also be done in children, with a history of persistent jaundice as a newborn.
How is the Specimen Collected for Glucose-6-Phosphate Dehydrogenase Test?
Sample required: Blood
- Blood sample is drawn through a needle inserted into the vein (arm) or obtained through finger prick
- In newborns, a heel stick sample is obtained
Preparation required: Testing for G6PD levels should not be done when an individual is having an active hemolytic episode, as this may give false results. Testing should be performed, only when the crisis has resolved.
What is the Significance of the Glucose-6-Phosphate Dehydrogenase Test Result?
A low level of G6PD indicates deficiency and the possibility of hemolysis on exposure to certain triggers. It does not, however, predict the severity of the symptoms.
The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.
Additional and Relevant Useful Information:
G6PD Testing should not be done immediately following a blood transfusion, as this may mask any deficiencies.
Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.