Test Catalog

Test Id : P5NT

Pyrimidine 5' Nucleotidase, Blood

Useful For
Suggests clinical disorders or settings where the test may be helpful

Evaluation of marked basophilic stippling


Evaluation of hemolytic anemia

Method Name
A short description of the method used to perform the test

Kinetic Spectrophotometry

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Pyrimidine 5' Nucleotidase, B

Lists additional common names for a test, as an aid in searching


P5NT deficiency

Hemolytic anemia

Basophilic stippling

uridine 5' monophosphate hydrolase deficiency

UMPH1 deficiency


Specimen Type
Describes the specimen type validated for testing

Whole Blood ACD-B

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing


Preferred: Yellow top (ACD solution B)

Acceptable: Lavender top (EDTA)

Specimen Volume: 5 mL


If not ordering electronically, complete, print, and send a Benign Hematology Test Request Form (T755) with the specimen.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

3 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

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

Useful For
Suggests clinical disorders or settings where the test may be helpful

Evaluation of marked basophilic stippling


Evaluation of hemolytic anemia

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Pyrimidine 5' nucleotidases (P5'Ns) are catabolic enzymes that regulate cellular nucleotide and nucleoside levels through the dephosphorylation of noncyclic nucleoside 5’-monophosphates. P5’N activity is much higher in reticulocytes than in aged red cells due to increased demand during erythroid maturation. Reticulocyte ribosomal RNA degradation results in pyrimidine nucleotide residues that require conversion to nucleosides to allow diffusion outside the cell. Disruption of this process results in intracellular pyrimidine nucleotide accumulation visible as coarse basophilic stippling. Several different 5'-nucleotidase (5’NT) enzymes have been identified with distinctive substrate specificity, cellular localization, and tissue distribution. Only P5’N type 1 is known to be associated with P5'N deficiency (also called uridine 5' monophosphate hydrolase deficiency), a cause of congenital nonspherocytic hemolytic anemia (OMIM 266120, autosomal recessive). The disorder manifests as mild/compensated to moderate hemolytic anemia with persistent reticulocytosis. Additional features include jaundice/neonatal hyperbilirubinemia, splenomegaly, and characteristic marked basophilic stippling on the peripheral blood smear. Coincident hemoglobin E (Hb E) may lead to a more severe hemolytic anemia. P5'N deficiency is caused by homozygous or compound heterozygous alterations in the NT5C3A gene, mapped to chromosome 7p14. Assaying for the presence of pyrimidine nucleotides serves as a surrogate marker for P5'N deficiency and is not specific for a diagnosis of hereditary P5’N deficiency. Enzyme function is magnesium ion-dependent and is inhibited by metal chelating reagents, such as EDTA. Activity is inhibited by heavy metal ions including lead, mercury, copper, nickel, and cadmium, and toxic levels can cause accumulation of intracellular pyrimidine nucleotides.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.


Provides information to assist in interpretation of the test results

A normal result indicates the absence of pyrimidine nucleotides and indicates normal pyrimidine 5' nucleotidase (P5'N) function.


An abnormal result (abnormal spectral scan) indicates the presence of pyrimidine nucleotides and possible P5'N deficiency. Enzyme activity is inhibited by heavy metal ions including lead, mercury, copper, nickel, and cadmium. Toxic levels can cause accumulation of intracellular pyrimidine nucleotides. If results are abnormal clinical correlation is recommended to exclude heavy metal poisoning.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

This assay serves as a surrogate marker for decreased pyrimidine 5' nucleotidase (P5'N) activity from any cause and is not specific for a diagnosis of hereditary P5’N deficiency.


Enzyme activity is inhibited by metal chelating reagents, such as EDTA.


Since enzyme activity is inhibited by heavy metal ions (including lead, mercury, copper, nickel, and cadmium) and toxic levels can cause accumulation of intracellular pyrimidine nucleotides, clinical correlation to exclude heavy metal poisoning is indicated forabnormal results.


Recent transfusion can result in false negative results.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Rees DC, Duley JA, Marinaki AM: Pyrimidine 5' nucleotidase deficiency. Br J Haematol. 2003 Feb;120(3):375-383

2. Zanella A, Bianchi P, Fermo E, Valentini G: Hereditary pyrimidine 5'-nucleotidase deficiency: from genetics to clinical manifestations. Br J Haematol. 2006 Apr;133(2):113-123

3. Fairbanks VF, Klee GG: Biochemical aspects of hematology. In: Burtis CA, Ashwood ER, eds. Tietz Textbook of Clinical Chemistry. 3rd ed. WB Saunders;  1999:1642-1647

4. Gregg XT, Prchal JT: Red blood cell enzymopathies. In: Hoffman R, Benz, Jr EJ, et al, eds. Hematology : Basic Principles and Practice, 7th ed. Elsevier; 2018:616-625

5. Warang P, Roshan C, Kedar P: Lead poisoning induced severe hemolytic anemia, basophilic stippling, mimicking erythrocyte pyrimidine 5'-nucleotidase deficiency in beta thalassemia minor. J Clin Toxicol. 2017;7(2):346. doi: 10.4172/2161-0495.1000346

Method Description
Describes how the test is performed and provides a method-specific reference

Pyrimidine nucleotides have a spectral absorption curve that is markedly different from that exhibited by (normally present) adenine nucleotides (eg, adenosine triphosphate). The former have a peak at about 270 nm; the latter at about 257 nm. Thus, pyrimidine 5' nucleotidase deficiency may be ascertained by demonstrating a very high spectral absorption maximum of 270 nm in erythrocyte extracts.(Beutler E: Red Cell Metabolism. A Manual of Biochemical Methods. 3rd ed. Grune and Stratton; 1984:100-102; van Solinge WW, van Wijk: Enzymes of the red blood cell. In: Rifai N, Horvath AR, Wittwer CT: eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018:chap 30)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

10 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

1 week

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

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  • Prospective clients should contact their account representative. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

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 US Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
P5NT Pyrimidine 5' Nucleotidase, B 2902-5
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
2734 Pyrimidine 5' Nucleotidase, B 2902-5

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports