Pyruvate kinase deficiency is a genetic disorder affecting red blood cells that carry oxygen to all cells in the body. People with pyruvate kinase deficiency have chronic hemolytic anemia, meaning that their red blood cells break down prematurely, causing a shortage in the body.
The complications for people with pk deficiency can be mild or severe, depending on their individual condition. In infants, severe symptoms can be life-threatening. Some people may need regular blood transfusions too.
How Prevalent Is PK Deficiency?
Pyruvate kinase deficiency has been identified in over 500 families. However, research shows that the condition could be highly underdiagnosed, as there is no way to identify mild cases.
Pk deficiency is not limited to a particular ethnic group. Instead, it affects all populations, causing notable symptoms in every 1 out of 20,000 people from Europe. In the U.S., the condition is common in the Pennsylvanian Old Amish population.
It occurs equally in women and men.
Causes of Pyruvate Kinase Deficiency
Pyruvate kinase is an essential enzyme in the energy-making process. Red blood cells convert glucose to pyruvate to produce energy. The product of this reaction is adenosine triphosphate (or, ATP), which is the energy currency of the body.
Pyruvate kinase plays its role in the last step of the process, converting phosphoenolpyruvate into ATP and pyruvate. In its absence, red blood cells cannot make enough energy and start breaking down.
Usually, red blood cells break down or undergo hemolysis in 120 days, but if they do not have enough pyruvate kinase, they only last a few weeks or days.
A mutation in the PKLR gene causes pyruvate kinase deficiency. This gene is present in the liver and red blood cells, containing instructions to make the pyruvate kinase enzyme.
If there is a change in the gene's structure, it does not code properly for the enzyme, leading to deficiency. In some cases, this may be caused by leukemia or other blood diseases. Such a condition is called secondary pyruvate kinase deficiency, since it is not genetic.
Symptoms of Pyruvate Kinase Deficiency
Pyruvate kinase deficiency symptoms vary from one person to another. The most common symptom is red blood cell breakdown, which causes hemolytic anemia. The signs of this condition include:
- Fatigue
- Lethargy
- Jaundice
- Pale skin
- Recurrent gallstones
- Yellowing eyes
If the condition is severe, the symptoms start showing in the fetal stage. A large amount of fluid starts building up around several body parts of the fetus. In newborns, the symptoms are anemia and jaundice.
Older children may have recurring jaundice and appear pale. Most people do not remain chronically anemic as adults, but they may still have anemic episodes if they are pregnant, infected, or stressed.
Some people may also develop splenomegaly, an enlarged spleen. The spleen filters red blood cells, so when red blood cells break down at an abnormal rate, the spleen has to increase its function. Therefore, it becomes enlarged. This condition is painless.
Pyruvate Kinase Deficiency Diagnosis (Pk Test)
A doctor can look at the kinase deficiency symptoms to diagnose the problem. Additionally, they can look at your family history, perform specialized tests, and conduct a clinical evaluation.
The standard diagnosis for pyruvate kinase deficiency is the pk test. In this procedure, pyruvate kinase's activity per unit of hemoglobin in the red blood cells is measured. If the enzyme's activity is low, that indicates the possibility of pk deficiency.
Not all labs or hospitals can perform this test. Samples are sent to specialized centers.
Doctors can also use molecular genetic testing to confirm pk deficiency. The genetic test detects PKLR gene mutations that cause the disorder. Again, this test can only be performed in specialized labs.
Pyruvate Kinase Deficiency Treatment
Pyruvate kinase deficiency treatment differs from one person to another. A whole team of specialists is required to treat the problem.
Doctors often use phototherapy, a procedure in which intense light is shone on bare skin to speed up the breakdown of bilirubin, which causes jaundice when present in excess.
Additionally, some adults and children may need blood transfusions to relieve symptoms. In cases where the spleen enlarges, a splenectomy may be performed. This procedure involves the removal of the spleen surgically.
What to Do if You Think You Might Have PK Deficiency
Pyruvate kinase deficiency is a serious condition that requires immediate medical attention. To get medical advice, look for doctors who have experience treating this illness. You can find these professionals by researching clinical trials, advocacy organizations, or medical journal articles.