54 Pyruvate Kinase (PK) Deficiency

Michelle To and Valentin Villatoro

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.

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A Laboratory Guide to Clinical Hematology by Michelle To and Valentin Villatoro is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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