Pyruvate Kinase, Erythrocytes
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Deficiencies of most of the enzymes of the Embden-Meyerhof (glycolytic) pathway, including pyruvate kinase (PK), have been reported. PK deficiency, although rare, is the erythrocyte enzyme deficiency most frequently found to be a cause of congenital nonspherocytic hemolytic anemia. It is an autosomal recessive disorder. Thus, the parents of affected patients are heterozygotes. Patients usually present during early childhood with anemia, icterus, and splenomegaly. Hemolytic disease of the newborn is common in persons with PK deficiency.
Work-up of cases of nonspherocytic hemolytic anemia
Investigating families with pyruvate kinase deficiency to determine inheritance pattern and for genetic counseling
Most pyruvate kinase (PK) deficient patients have 5% to 25% of normal activity.
Elevated PK concentrations can be found in those patients with younger erythrocyte population. This may be due to the patient being a newborn or young red cells are being produced in response to the anemia (reticulocytosis).
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Because leukocytes also contain pyruvate kinase (PK) that is not diminished in hereditary erythrocytic PK deficiency, freeing the blood of white blood cells is always critical to this test.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
> or =12 months: 6.7-14.3 U/g Hb
Reference values have not been established for patients who are <12 months of age.
Clinical References Provides recommendations for further in-depth reading of a clinical nature
Beutler E: Hereditary nonspherocytic hemolytic anemia: pyruvate kinase deficiency and other abnormalities. In Hematology. Fourth edition. Edited by WJ Williams, E Beutler, AJ Erslev, MA Lichtman. New York, McGraw-Hill Information Services Company, Health Professions Division, 1990, pp 606-612