A G6PD deficiency is an inherited condition. It occurs when the body does not have enough of a specific enzyme, called glucose 6 phosphate dehydrogenase. This enzyme helps the red blood cells be able to function in a normal way. When this deficiency is present, it may cause hemolytic anemia after exposure to certain foods or medications. Even a simple infection can be enough to cause anemia to appear.
In the United States, the most common time for this blood test to be ordered is for newborns who have unexplained and persistent jaundice. Some states in the US do require the G6PD blood test as part of the mandatory post-birth screening process.
It may also be ordered when adults are experiencing hemolytic anemia for an unknown reason. Jaundice and dark urine for unknown reasons may also trigger this test. A medical provider may also ask about recent medication or food exposures, focusing on fava beans and sulfa drugs particularly, to determine if a genetic cause is the reason behind the anemia.
Who Is Most Affected By G6PD Deficiency?
The most common form of G6PD deficiency is found in individuals who have an African ancestry. As the red blood cells age, they lose up to 75% of this enzyme. Because of this, the blood test may not be ordered until several weeks after an episode with hemolytic anemia.
Other forms of G6PD deficiency can occur within any family history. More than 440 different gene variations have been documented at the time of this writing across all races and ethnicities. The WHO classifies these variations into 5 different groups based on their specific impact to health, but only the most common forms of G6PD deficiency are typically tested for in most locations.
When To Have the G6PD Blood Test Ordered
There are specific signs and symptoms that will trigger a medical provider to order the G6PD blood test. These include unexplained issues with weakness or fatigue, pale skin, fainting, shortness of breath, a rapid heart rate, and an enlarged spleen. Liver health issues, including the presence of jaundice or red/brown urine, may also be present.
Sometimes these signs or symptoms may not be present, but other blood tests may indicate the presence of hemolytic anemia. In these instances, the G6PD blood test may still be ordered to help determine an underlying health reason for abnormal results.
What Do the Test Results Mean?
If there is a G6PD deficiency present, then the test results will show low levels of the enzyme present in the sample. This test is unique, however, in the fact that those who are affected will be more likely to experience symptoms when they have been exposed to a trigger. Because of this, low test results cannot be used as an indication of how someone will react in any given set of circumstances.
The signs and symptoms of a G6PD deficiency can vary from person to person and even from episode to episode.
Normal test results in men are typically indicative that a deficiency is not present. If the blood test was performed during an episode of hemolytic anemia, however, then the test should be duplicated several weeks later to confirm the result.
Women can be carriers of the genetic causes of a G6PD deficiency. This means they may have some red blood cells that are G6PD deficient and others that are not. Women who are carriers may have results that are low, but near normal, and experience no bothersome symptoms. Some women, though rare, have two mutated gene copies and will always have low test results, but typically not experience anemia.
Here’s What You Need To Know About the G6PD Blood Test
Although this enzyme deficiency is most common in those with an African ancestry, there are higher rates of prevalence in those with Mediterranean and Asian descent when compared to the rest of the world’s general population. The geographical areas of influence are similar to that of malaria outbreaks, which has some researchers believing that G6PD deficiencies from mutations may be an evolution of the human condition to offer a survival advantage to the disease.
There are some enzyme variants that may not be able to be distinguished by certain laboratories. Your medical provider may need to have your test examined by a specific laboratory and this may delay test results by several days.
Blood transfusions are known to mask G6PD deficiencies.
The G6PD blood test is designed to shed light on episodes of hemolytic anemia and what is causing them. Not all forms of anemia are caused by this enzyme deficiency, so if you’re experiencing bothersome signs or symptoms, schedule an appointment with your medical provider right away. This will be the first step toward receiving the answers you may need.