Pyruvate Kinase Deficiency: Case Study.
Pyruvate Kinase (PK) Deficiency can lead to substantial clinical consequences. It can affect red cell metabolism leading to hemolysis. Splenectomy is a treatment that is designed to decrease loss of erythrocytes.Pyruvate kinase catalyzes the key glycolytic reaction:
PEP + ADP ------> pyruvate + ATP
Pyruvate is converted to acetyl CoA for the TCA cycle. Under anaerobic conditions, pyruvate is converted to lactate. Erythrocytes, which have no mitochondria, are dependent on glycolysis for energy. Deficiencies of PK will therefore, frequently affect the red blood cell.
For more background on pyruvate kinase, click here.
The Case: A 37 year old man with a PK deficiency is currently being followed in the hematology clinic at KCH. His hemoglobin levels were between 5-7 gm/dl (normal for a male being >13.5 gm/dl). He occasionally had more severe decreases in his hemoglobin levels, usually precipitated by viral infections (parvovirus, in particular, is known to suppress erythropoiesis in the bone marrow). Because of this, in an effort to decrease hemolysis due to PK deficiency, he has had a splenectomy. (Erythrocytes are normally removed from the circulation by the spleen and a splenectomy allows his erythrocytes to survive longer in the circulation.) Subsequently, his hemoglobin levels have ranged from 6-9 gm/dl and he is usually asymptomatic from his anemia. We questioned him about the symptoms of anemia when he comes to clinic. These include weakness, fatigue, shortness of breath and dizziness. Because he has had a splenectomy he is at a slightly increased risk for overwhelming bacterial infection. We therefore monitor signs of symptoms of infection closely. He is presently stable and actually participates in sports activities.