Red blood cells (RBCs) carry oxygen throughout your body. An enzyme known as pyruvate kinase is necessary for your body to make RBCs and function properly. The pyruvate kinase test is a blood test used to measure the levels of pyruvate kinase in your body.
When you have too little pyruvate kinase, your RBCs 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
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 1-in-4 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. Your doctor may also order the test upon identifying symptoms of pyruvate kinase deficiency. Data collected from a physical exam, the pyruvate kinase test, and other blood tests will help confirm a diagnosis.
You don’t need to do anything specific to prepare for the pyruvate kinase test. However, the test is often administered to young children, so parents may want to talk to their kids 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 collect into a tube and go 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 during the blood draw. There may be some pain at the injection site from the needle sticks. Afterwards, 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 plus or minus 16 units of pyruvate kinase per 100 milliliters of RBCs. Low levels of pyruvate kinase indicate the presence of pyruvate kinase deficiency.
There is no cure for pyruvate kinase deficiency. If you’re 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 RBCs. A blood transfusion is an injection of blood from a donor.
If the symptoms of the disorder are more severe, your doctor may recommend a splenectomy (removal of the spleen). 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. The good news is that treatment will almost certainly reduce your symptoms and improve your quality of life.