6-Phosphogluconic Dehydrogenase

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6Phosphogluconic-Dehydrogenase (G6PD) is an enzyme that exists in the red blood cells of the human body and assists in the metabolism of glucose. During this metabolism, NADPH (reduced coenzyme II) is produced to protect the red blood cells from the threat of oxidative substances. When G6PD is deficient, if the body comes into contact with specific oxidizing substances or takes such drugs, red blood cells are easily destroyed and acute hemolysis occurs. G6PD is essential for the pentose phosphate bypass, and this pathway can provide NADPH for myelin formation.

Enzyme structure

The overall structure of 6-phosphogluconate dehydrogenase and several key residues seem to be very conserved in various species. The enzyme is a dimer, each subunit contains three domains. The N-terminal coenzyme binding domain contains a Rossmann fold with other α/β units. The second domain consists of many alpha-helix structures, and the C-terminal domain consists of short tails. The tails of the two subunits interact with each other to form a movable cover on the active site of the enzyme.

Figure 1. 6Phosphogluconic-Dehydrogenase.

Clinical significance

• Neonatal jaundice: Nearly one-third of neonatal jaundice is caused by G6PD deficiency. If the degree of jaundice is not serious, light treatment is sufficient. If severe hemolytic jaundice occurs, exchange blood treatment should be given if necessary. Generally, if it can be detected early and treated properly, it can be restored within two or three days.
• Acute hemolytic anemia: When the patient comes into contact with oxidizing substances, hemolytic reaction occurs immediately. Symptoms include: pale complexion, jaundice all over, poor spirits, poor appetite, and dark brown urine. In severe cases, it can lead to respiratory distress, heart failure, even shock and unconsciousness, and life-threatening. Emergency blood transfusions are often needed to save lives. Therefore, when a child has any of the above symptoms, he should be sent to a doctor as soon as possible, and the medical staff should be actively informed that the child has G6PD deficiency to help make a faster and correct diagnosis and treatment.
• Oxidizing substances that can cause hemolysis include (1) antimalarial drugs (2) sulfonamides in anti-infective drugs (3) certain antipyretic analgesics such as the famous aspirin (4) certain Some drugs used to control urinary tract infections in the past. In addition, some chemicals such as mothballs (stinky pills), gentian violet (purple potion) and methyl blue can also cause hemolysis. In terms of food, children often experience acute hemolytic anemia after eating broad beans and their products, so this disease is also commonly known as fava bean disease.
• Hereditary glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common type of inherited enzyme deficiency. This disease is genetically related and cannot be caused by eating broad beans.

Clinical observation and nursing

1. Observation of vital signs Hemolysis is a gradual aggravating process. After admission, the vital signs observation and T, P, R measurement should be strictly performed to prevent the damage of vital organs caused by anemia and hypoxia. Children with drowsiness, coma, convulsions, headaches, vomiting, shortness of breath, irregular breathing, weak pulse or oliguria, and urinary obstruction, all indicate cerebral edema, acute heart failure, renal failure, and should be reported to the doctor in time and given sedation, strong heart, diuretic and other treatments to maintain the physiological functions of important organs.
2. Observation of anemia should assist the doctor to closely observe the progress and speed of anemia, make a good measurement and record of hemoglobin, timely replenish the lost red blood cells, and correct anemia.
3. Observation of Urine Mainly observe the exclusion status of hemoglobinuria. When a large amount of hemolysis occurs, the urine becomes the color of strong tea or soy sauce. With the termination of hemolysis, urine gradually turns from thick to light and returns to normal. Observing the color of urine can predict the degree and outcome of hemolysis. At the same time, the urine output should be recorded. If there is oliguria or closed urine, it indicates that hemolytic uremic may occur. Therefore, treatments such as alkalization of urine were given after admission to prevent acid hemoglobin from blocking the renal tubules and causing acute renal failure.