Pyruvate Kinase (PK), Red Blood Cell

PK is an enzyme involved in glycolysis. Genetic defects of this enzyme cause the disease known as PK deficiency. This deficiency is one of the most common enzymatic defects of the erythrocyte. The disorder manifests clinically as a hemolytic anemia, and the symptomatology is less severe than hematologic indices indicate. The clinical severity of this disorder varies widely, ranging from a mildly compensated anemia to severe anemia of childhood. Most affected individuals do not require treatment. Individuals who are most severely affected may die in utero of anemia or may require blood transfusions or splenectomy, but most of the symptomatology is limited to early life and to times of physiologic stress or infection.

Normal range: 9.0 " “22.0 U/g Hb.

Use

Evaluation of nonspherocytic hemolytic anemia

Investigating families with PK deficiency to determine inheritance pattern and for genetic counseling

Interpretation

Increased in patients with younger erythrocyte population

Decreased in congenital nonspherocytic hemolytic anemia

Limitations

Patients who have recently received transfusions have normal donor cells that may mask PK-deficient erythrocytes.

Most PK-deficient patients have 5 " “25% of normal activity.

Leukocytes also contain PK, that is not decreased by hereditary erythrocyte PK deficiency, freeing the blood of WBC is critical for accuracy.