Retired Professor of Paediatrics and Neonatal Medicine, Imperial College School of Medicine, University of London
What is G6PD deficiency?
G6PD deficiency is an inherited disease that can cause anaemia, or a low haemoglobin level. The abnormal gene is carried on the X chromosome and so the condition is much commoner in males. It is a common condition in north India, particularly among Punjabis and the people who have migrated from Pakistan.
G6PD deficiency is a condition in which the red blood cells lack the enzyme glucose-6-phosphate dehydrogenase (G6PD). This enzyme acts as an accelerator to speed up the chemical reaction that burns the sugar for energy. This enzyme is present in all the cells of the body.
G6PD found in the red blood cells, and protects these cells against strong oxygen compounds (oxidants) that may collect in case of a fever or when certain medicines are taken. In the absence of G6PD, these strong compounds may damage some components of the red blood cells such as the red pigment, called haemoglobin. This damage reduces the ability of the red blood cells to carry oxygen. In some cases the cells may get destroyed resulting in anaemia.
What are the causes?
G6PD deficiency is inherited and is found in both males and females. Males are more severely affected. Sudden attacks of G6PD deficiency can be caused by any serious illness and certain medicines such as:
Medicines for the treatment of malaria
Medicines for fever and pain
Vitamin C ( only in very high doses)
What are the symptoms?
Some people with G6PD deficiency show no symptoms at all. People with this disorder are not normally anaemic and show no evidence of the disease until the red blood cells are exposed to an oxidant or stress. In others, the signs and symptoms may include:
Prolonged and severe jaundice in the new-born: an abnormal yellow colour of the skin and eyes that is present in the first few days after birth
An enlarged spleen or liver
Weakness and severe fatigue
Pain in the abdomen or back
Fever and chills
In severe cases there may be:
Rapid heart beat and low blood pressure
Congestive heart failure, a condition in which the heart is unable to pump blood effectively to all parts of the body
How is the diagnosis made?
The G6PD deficiency is suspected when symptoms like jaundice and anaemia occur. The doctor may suggest tests to check the level of haemoglobin in blood and urine, bilirubin levels and serum hepatoglobin. Blood tests include complete blood count, red blood cell count and reticulocyte counts. Other tests such as peripheral blood smear, methylene blue test and methaemoglobin reduction test may also be conducted.
A specific diagnosis can be made by measuring the amount of G6PD activity in the red blood cells. In some cases, a blood test called protein electrophoresis may need to be done to confirm the diagnosis.
What is the treatment?
Most people with G6PD deficiency do not need regular treatment. However, the treatment depends on the cause and the symptoms. If the cause for the acute episode is an infection, it should be treated and in case the cause is a drug, it needs to be either stopped or replaced. The genetic defect cannot be cured at present.
Other treatments include oxygen, fluids, or medication to treat problems such as congestive heart failure or kidney failure. Blood transfusion and surgery of the spleen may be needed in some cases. A treatment called iron chelation therapy may be needed if iron overload occurs. This therapy helps the body to get rid of excess iron. Persons affected by G6PD deficiency must carry a card with the diagnosis so that the treating doctor is alerted before any drug is started.