What does this LOINC code represent?

This LOINC code identifies a lab observation, measurement, question, or clinical concept in a standardized format.

Is this enough to understand my test result?

No. The code identifies the test or observation, but the interpretation depends on the actual result, reference range, and clinical context.

LOINCActiveBoth

LOINC Code 85379-6: Purine/Pyrimidine Spectrophotometry (RBC) [Ratio]

Name: LOINC Code 85379-6: Purine/Pyrimidine Spectrophotometry (RBC) [Ratio]
Creator: HealthAssure Clinical Team
Published: 2026-05-21T09:00:13.315Z

85379-6 is a LOINC code used to identify Purine/Pyrimidine Spectrophotometry (RBC) [Ratio] in laboratory and clinical observation data. You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges. LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component Purine/pyrimidine. It is commonly used with the system or sample type RBC.

Reviewed by HealthAssure Clinical TeamUpdated 21 May 2026

What is this code?

LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component Purine/pyrimidine. It is commonly used with the system or sample type RBC.

When is it used?

Used in lab systems, EHRs, and clinical data exchange.
May identify a test, observation, survey item, or clinical document request rather than a diagnosis.
Status: ACTIVE
Order vs observation: Both
Method: Spectrophotometry

What it does not mean

The code identifies the observation or test, not the actual result.

Key facts

Purine/Pyrimidine [Ratio] in Red Blood Cells by Spectrophotometry

Purine/pyrimidine

The purine to pyrimidine ratio is a marker of pyrimidine-5-nucleotidase (P5N) which is an enzyme in the cytoplasm of human red blood cells. The function of P5N is unknown but a deficiency of the enzyme causes congenital haemolytic anemia. Individuals who are heterozygous for the recessive P5N gene demonstrate no clinical or hematological abnormalities while those homozygous for the recessive P5N gene have a corresponding 5-30% reduction in normal enzyme activity. P5N deficiency leads to chronic non-spherocytic haemolytic anaemia associated with mild to moderate hemolysis, increased basophilic stippling in 5% of the red blood cells and an elevation of red cell glutathione and pyrimidine nucleotides. The diagnosis of P5N deficiency is based on the change in the level of cytidine and uridine in red blood cells which is normally very low but increases to over 50% in P5N deficient patients. Measurement of P5N is by light absorption at different wavelengths. In acidic solution pyrimidine nucleotides absorb the maximum amount of light at 280 nanometers (nm). Purine nucleotides absorb the maximum amount of light at 260 nm. The ratio of light absorbed at 260 nm to that at 280 nm in a pool of red blood cells indicates the relative amount of purines to pyrimidines. The ratio is lower than normal when pyrimidine levels are increased.[PMID23992312][ Dacie and Lewis Practical Haematology, 11th edition, Barbara J. Bain, Imelda Bates, Mike A. Laffan, S. Mitchell Lewis, p259]

Chemistry; Erythrocytes; Point in time; QNT; Quan; Quant; Quantitative; Random; Ratios; Red blood cells; Red blood corpusles; Rto

Where you may see this code

You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges.

Common synonyms

Purine/Pyrimidine Spectrophotometry (RBC) [Ratio]Purine/Pyrimidine [Ratio] in Red Blood Cells by SpectrophotometryPurine/Pyrimidine RBC Spect-RtoPurine/pyrimidineCHEMPurine/Pyrimidine, Red blood cellsRatio

Frequently asked questions

Code details

Code85379-6

SystemLOINC

Display namePurine/Pyrimidine Spectrophotometry (RBC) [Ratio]

DescriptionPurine/pyrimidine

Short namePurine/Pyrimidine RBC Spect-Rto

ComponentPurine/pyrimidine

PropertyRatio

TimingPt

System (specimen)RBC

ScaleQn

MethodSpectrophotometry

ClassCHEM

Example unitsratio

StatusACTIVE

Order/ObservationBoth

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.61

Last changed2.61

Consumer names

Purine/Pyrimidine, Red blood cells

Part names

Purine/pyrimidineRatioPtRBCQnSpectrophotometryPoint in time (spot)Red Blood Cells

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from LOINC. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.