54 Pyruvate Kinase (PK) Deficiency
Michelle To and Valentin Villatoro
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- A peripheral blood smear with a pyknocyte* shown by the arrow (A). 100x oil immersion. From MLS Collection, University of Alberta, https://doi.org/10.7939/R3VX06J4H
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
Mutation:1,2
Mutations in the PKLR gene leading to decreased levels of pyruvate kinase.
Inheritance:1,2
Autosomal recessive
Complications:1,2
Chronic hemolytic anemia
Splenomegaly
Jaundice
Gallstones
Notes:1
WBCs contain more pyruvate kinase than RBCs.
Laboratory Results for PK Deficiency:1
|
CBC: Hb: Decreased RETIC: Increased
*Note: The term “pyknocyte” is not universally used. It refers to a small, dehydrated, dark-colored RBC. |
PBS: Normocytic Normochromic Echinocytes Pyknocytes* Post-splenectomy shows varying degrees of anisocytosis and poikilocytosis |
Other Tests: Osmotic Fragility: Normal Pyruvate Kinase Assay: Decreased Indirect bilirubin: Increased LDH: Increased Haptoglobin: Decreased or absent |
References:
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.
