Normal PK Function:
Pyruvate Kinase catalyzes the conversion of phosphoenolpyruvate to pyruvate which results in the production of ATP from ADP. A lack of pyruvate kinase results in the ability of cells to maintain proper cell shape, normal lifespan, and low levels of 2,3-PBG.1,2
Mutations in the PKLR gene leading to decreased levels of pyruvate kinase.
Chronic hemolytic anemia
WBCs contain more pyruvate kinase than RBCs.
Laboratory Results for PK Deficiency:1
*Note: The term “pyknocyte” is not universally used. It refers to a small, dehydrated, dark-colored RBC.
Post-splenectomy shows varying degrees of anisocytosis and poikilocytosis
Osmotic Fragility: Normal
Pyruvate Kinase Assay: Decreased
Indirect bilirubin: Increased
Haptoglobin: Decreased or absent
1. Lake M, Bessmer D. Hemolytic anemia: enzyme deficiencies. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 334-47.
2. Keohane EM. Intrinsic defects leading to increased erythrocyte destruction. In: Rodak’s hematology clinical applications and principles. 5th ed. St. Louis, Missouri: Saunders; 2015. p. 367–93.