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Test ID: PK1 Pyruvate Kinase Enzyme Activity, Blood


Specimen Required


Collection Container/Tube:

Preferred: Yellow top (ACD solution B)

Acceptable: Lavender top (EDTA)

Specimen Volume: 6 mL

Collection Instructions: Send specimen in original tube. Do not transfer blood to other containers.


Useful For

Evaluation of nonspherocytic hemolytic anemia

 

Evaluation of neonatal anemia or jaundice

 

Evaluation of unexplained noninfectious hepatic failure

 

Evaluation of unexplained iron overload

 

Evaluation of unusually severe hemoglobin S trait

 

Evaluation of unusually severe glucose 6-phosphate dehydrogenase deficiency

 

Investigating families with pyruvate kinase deficiency to determine inheritance pattern and for genetic counseling

Method Name

Kinetic Spectrophotometry

Reporting Name

PK Enzyme Activity, B

Specimen Type

Whole Blood ACD-B

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood ACD-B Refrigerated 20 days

Clinical Information

Deficiencies of most of the enzymes of the Embden-Meyerhof (glycolytic) pathway, including pyruvate kinase (PK), have been reported. PK deficiency (OMIM 266200) is the erythrocyte enzyme deficiency most frequently found to be a cause of chronic nonspherocytic hemolytic anemia (CNSHA). It is an autosomal recessive disorder and parents of affected patients are typically carriers. Some PK carrier states can exacerbate other RBC disorders (ie, coincident glucose 6-phosphate dehydrogenase deficiency or hemoglobin S trait).

                                                          

Clinically significant PK deficiency manifests in widely variable severity ranging from incidental compensated mild normocytic anemia to severe anemia. Neonatal jaundice is very common and a significant subset of neonates has perinatal complications. Other symptoms include early gallstones and splenomegaly. Iron overload, even in the absence of frequent transfusions, is very common. Rare severe PK deficiency is associated with hydrops fetalis/fetal demise or unexplained noninfectious hepatic failure. Acquired PK deficiency can arise secondary to myeloid neoplasms.

Reference Values

≥12 months of age: 5.5-12.4 U/g Hb

Reference values have not been established for patients who are less than12 months of age.

Interpretation

Pyruvate kinase (PK) deficiency is the most easily masked of the RBC enzyme disorders and can be difficult to classify without complete information, which may require comparison to other RBC enzyme activity levels or correlation with results of PKLR gene molecular testing (PKLRG / Pyruvate Kinase Liver and Red Blood Cell [PKLR] Full Gene Sequencing and Large Deletion Detection, Varies). Most hemolytic anemias due to PK deficiency are associated with activity levels less than 40% of mean normal. However, some patients with clinically significant hemolysis can have normal or only mildly decreased PK enzyme activity, which paradoxically may occur in individuals with the most severe symptoms. Isolated carriers (heterozygotes) may show mildly decreased activity and are typically hematologically normal, although the carrier state may exacerbate other RBC disorders such as glucose 6-phosphate dehydrogenase deficiency, RBC membrane disorders, or hemoglobinopathies. Some alterations in other genes (ie, KLF1) can be associated with decreased PK levels.

 

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). Rare PK deficient cases have been associated with minimally increased PK levels; however, comparison to other RBC enzyme activity would be critical in these cases for accurate interpretation.

Clinical Reference

1. Grace RF, Bianchi P, van Beers EJ, et al. The clinical spectrum of pyruvate kinase deficiency: data from the Pyruvate Kinase Deficiency Natural History Study. Blood. 2018 May 17;131(20):2183-2192

2. Gallagher PG, Glader B: Diagnosis of pyruvate kinase deficiency. Pediatr Blood Cancer. 2016 May;63(5):771-772

3. Grace RF, Zanella A, Neufeld EJ, et al: Erythrocyte pyruvate kinase deficiency: 2015 status report. Am J Hematol. 2015 Sep;90(9):825-830

4. Zanella A, Fermo E, Bianchi P, Chiarelli LR, Valentini G: Pyruvate kinase deficiency: the genotype-phenotype association. Blood Rev. 2007 Jul;21(4):217-231

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

84220

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PK1 PK Enzyme Activity, B 32552-2

 

Result ID Test Result Name Result LOINC Value
PKCL PK Enzyme Activity, B 32552-2

Day(s) Performed

Monday through Saturday

Report Available

1 to 4 days
Mayo Clinic Laboratories | Hematology Catalog Additional Information:

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