Test Catalog

Test ID: P5NT    
Pyrimidine 5' Nucleotidase, Blood

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

Evaluation of persistent reticulocytosis and 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' nucleotidase (P5'NT) is involved in the catabolism of RNA, which is a normal constituent of reticulocytes but not of mature erythrocytes. A deficiency of P5'NT (also called uridine 5' monophosphate hydrolase)is a cause of congenital non-spherocytic hemolytic anemia (OMIM #266120) and is associated with a persistent reticulocytosis. Deficiency of P5’NT is caused by homozyogous or compound heterozygous mutations of the NT5C3A gene at chromosome 7p14 and results in the abnormal accumulation of pyrimidine nucleotides. The disorder is classically associated with basophilic stippling of the red blood cells. Assaying for the presence of pyrimidine nucleotides serves as a surrogate marker for P5’NT deficiency, as the enzymatic assay is difficult.

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.


Interpretation Provides information to assist in interpretation of the test results

A normal result indicates the absence of pyrimidine nucleotides and indicates normal P5'NT function. An abnormal result (abnormal spectral scan) indicates the presence of pyrimidine nucleotides and likely P5'NT deficiency, Lead poisoning can also inhibit P5NT function. If this is suspected, correlation with blood lead levels is recommended.

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

Lead inhibits P5NT activity; therefore, blood lead levels should be performed to exclude a reversible cause.

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. Fairbanks VF, Klee GG: Biochemical aspects of hematology. In Tietz Textbook of Clinical Chemistry. Third edition. Edited by CA Burtis, ER Ashwood, Philadelphia, WB Saunders Co., 1999, pp 1642-1647