Red blood cells (RBCs) carry oxygen throughout your body. An enzyme known as pyruvate kinase is needed for your body to make red blood cells and maintain their function. Pyruvate kinase deficiency is a genetic disorder.
When you have too little pyruvate kinase, your red blood cells break down faster than normal. This reduces the number of RBCs available to carry oxygen to vital organs, tissues, and cells. The resulting condition is known as hemolytic anemia and can have significant health consequences.
The symptoms of hemolytic anemia include:
- jaundice (yellowing of the skin)
- enlargement of the spleen (the spleen’s primary job is to filter blood and to destroy old and damaged RBCs)
- anemia (a shortage of healthy RBCs)
- pale skin
The pyruvate kinase test is a blood test that can be used to measure the levels of pyruvate kinase in your body. Your doctor can determine if you have pyruvate kinase deficiency based on the results of this and other diagnostic tests.
Pyruvate kinase deficiency is a genetic disorder that is autosomal recessive. This means that each parent carries the defective gene for this disease. Although the gene is not expressed in either of the parents (meaning that neither has pyruvate kinase deficiency), the recessive trait has a one-in-four chance of appearing in any children that the parents have together.
Children born to parents with the pyruvate kinase deficiency gene will be tested for the disorder using the pyruvate kinase test. The test may also be ordered if your doctor identifies symptoms of pyruvate kinase deficiency. Data collected from a physical exam, the pyruvate kinase test, and other blood tests will be used to confirm a diagnosis.
There are no specific preparations needed for the pyruvate kinase test. However, because the test is often administered to young children, parents may want to talk to their children about how the test will feel. You can demonstrate the test on a doll to help reduce your child’s anxiety.
The pyruvate kinase test is performed on blood taken during a standard blood draw. A nurse or doctor will take a sample of blood from your arm or hand using a small needle or a blade called a lancet.
The blood will be collected in a tube and sent to a lab for analysis. Your doctor will be able to provide you with information about the results and what they mean.
Patients undergoing the pyruvate kinase test may experience some discomfort when the blood sample is drawn. Needle sticks may result in pain at the injection site during the test. After the test, patients may experience pain, bruising, or throbbing at the injection site.
The risks of the test are minimal. Potential risks of any blood draw include:
- difficulty obtaining a sample, resulting in multiple needle sticks
- excessive bleeding at the needle site
- fainting as a result of blood loss
- the accumulation of blood under the skin, known as a hematoma
- development of infection where the skin is broken by the needle
The results of the pyruvate kinase test will vary based on the laboratory analyzing the blood sample. A normal value for the pyruvate kinase test is typically 179 + 16 units of pyruvate kinase per 100 milliliters of red blood cells. Low levels of pyruvate kinase indicate the presence of pyruvate kinase deficiency.
There is no cure for pyruvate kinase deficiency. If you are diagnosed with this condition, your doctor may recommend various treatments. In many instances, patients with pyruvate kinase deficiency will need to undergo blood transfusions to replace damaged red blood cells. A blood transfusion is an injection of blood from a donor.
If the symptoms of the disorder are more severe, a splenectomy (removal of the spleen) may be needed. Removing the spleen may help cut down on the number of RBCs that are being destroyed. Even with the spleen removed, symptoms of the disorder may remain. Treatment will almost certainly reduce your symptoms and improve your quality of life.