Pyruvate Kinase





To assess for an enzyme deficiency to assist in diagnosis of hemolytic anemia.

Patient Preparation

There are no food, fluid, activity, or medication restrictions unless by medical direction.

Normal Findings

(Method: Enzymatic) 4.6–11.2 units/g Hgb.

Critical Findings and Potential Interventions



(Study type: Blood collected in yellow-top [acid-citrate-dextrose (ACD)] tube. Specimens collected in a lavender-top [EDTA] or green-top [heparin] tube also may be acceptable in some laboratories; related body system: Circulatory/Hematopoietic system.)

Pyruvate kinase (PK) is an enzyme that forms pyruvate and adenosine diphosphate during glycolysis. Isoenzymes of PK are present in specific tissue: M1 type PK is mainly found in the heart, skeletal muscle, and brain; L type is found in the liver, kidney cortex, and intestine; M2 is found in leukocytes and most other tissues; type R is specifically found in red blood cells (RBCs). Deficiency of this enzyme can be acquired by ingestion of a drug or as an effect of liver disease. There is also a hereditary form of pyruvate kinase deficiency that can be transmitted as an autosomal recessive trait, meaning both parents must have the affected gene for the enzyme deficiency to be passed on to their offspring. RBCs lacking this enzyme have a membrane defect resulting from low levels of adenosine triphosphate and are more susceptible to hemolysis.


Evaluate chronic hemolytic anemia.

Interfering Factors

Factors that may alter the results of the study

  • Testing after blood transfusion may produce a falsely normal result.
  • The enzyme is unstable. The specimen should be refrigerated immediately after collection.

Potential Medical Diagnosis: Clinical Significance of Results

Increased in

Related to release of skeletal and cardiac specific isoenzymes of PK from damaged tissue cells.

  • Carriers of Duchenne muscular dystrophy
  • Muscle disease
  • Myocardial infarction

Decreased in

  • Hereditary pyruvate kinase deficiency (evidenced by autosomal recessive trait for PK enzyme deficiency):
    • Hereditary nonspherocytic hemolytic anemia
  • Acquired pyruvate kinase deficiency (related to interaction of medications used for therapy; related to release of leukocyte-specific isoenzymes from damaged leukocytes):
    • Acute leukemia
    • Aplasias
    • Other anemias

Nursing Implications, Nursing Process, Clinical Judgement

Before the Study: Planning and Implementation

Teaching the Patient What to Expect

  • Discuss how this test can assist in diagnosing anemia.
  • Explain that a blood sample is needed for the test.

After the Study: Implementation & Evaluation Potential Nursing Actions

Treatment Considerations

  • Address any concerns voiced by the patient or family.
  • Discuss the symptoms of hemolytic anemia: pale skin, confusion, fatigue, jaundice, weakness, fever, chills, palpitations, irregular heartbeat, back or abdominal pain.

Clinical Judgement

  • Consider how to overcome objections to the transfusion of blood and blood products.

Followup Evaluation and Desired Outcomes

  • Understands that depending on the results of this procedure, additional testing may be performed to evaluate or monitor disease progress and determine the need for a change in therapy.

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