NPU definition, structure and presentation

by | Nov 8, 2020 | NPU Concept model, General rules and principles

NPU definition, structure and presentation

Scope

 NPU definition encompasses essential information about an examination or a measurement. The syntax of a NPU definition comprises of a unique identifier, patient system, component, kind-of-property and measurement unit.

Syntax

Note 1: The question mark indicates the placeholder for the result value.

Note 2: The specifications in each string have the purpose to specify the description of the main strings when necessary.

By word

The NPU definition can be converted to a sentence:

The kind-of-property of component B in a patient’s system 1 is [?] measurement unit

Note 1: Component B is any object of interest and a part of system 1

Note 2: System 1 is any part, surroundings of a patient or a patient, comprising of component B and matrix

By mathematical equation

Note: This will appear for NPU definitions that belong to the rational, difference, logarithmic result type

Example

Definition by word:

The mass concentration of Haemoglobin in a patient’s blood is [?] g/L

Definition by mathematical equation

Reference
  1. Olesen H. Properties and units in the clinical laboratory sciences. I. Syntax and semantic rules (recommendation 1995). International Union of Pure and Applied Chemistry (IUPAC) and International Federation of Clinical Chemistry (IFCC). Eur J Clin Chem Clin Biochem. 1995;33(9):627-36.
  2. Ferard G, Dybkaer R, Fuentes-Arderiu X. Compendium of Terminology and Nomenclature of Properties in Clinical Laboratory Sciences : Recommendations 2016. 1 ed: Royal Society of Chemistry; 2016. 182 p.

Expressions

NPU definition can be expressed in several ways.

In order to make NPU definition understandable for clinicians and patients, a trivial name is often attached to a NPU definition. Trivial names may neither be unique or contain all information of the quantity. It is recommended to have a regulated system of trivial names governed by a central organisation in order to avoid misunderstandings.

Long version: NPU28309 Blood-Haemoglobin; mass concentration= ? g/L
Short version: NPU28309 Blood-Haemoglobin; mass c.= ? g/L

Trivial name: E.g. Hemoglobin test

Abbreviation: E.g.Hb

Note 1: A trivial name is less technical and more recognizable than a NPU definition that is more technical. A national trivial name may be attached to the national prefered term.

Note 2: The trivial name and abbrevation may also be used for a different NPU definition, e.g. NPUxxxxx Blood-Haemoglobin; subst. c.= ? mmol/L

Note 3: There is no official trivial name for NPU definitions but may be regulated by each national society or governmental body

Concepts

 The concepts in the NPU definition are defined and traceable to international terminology, ontology or nomenclature (see Principles of terminology and Medical and metrological vocabulary)

Language

 The lingua franca in NPU terminology is British English. Each country may translate NPU definitions into the country’s official language

Number of characters

 There is no limit of characters in the NPU code. However, the length of the NPU code should be limited to the extent of readability and understandability

Characters

Some characters and signs appear in NPU definitions. Their definitions are:

  • “And” means “and“ or “or” but not “the sum of”
    • Example: NPU56084 Syst(spec.)—Streptococcus and Enterococcus(DNA); taxon(proc.) = ?

Note: The result can differentiate between DNA from Streptococcus and Enterococcus

  • “+” means “the sum of”.
    • Example: NPU56942 Csf—Cryptococcus neoformans+Cryptococcus gattii species complex(DNA); arb.c.(proc.) = ?

Note: The result cannot differentiate between DNA from Cryptococcus neoformans+Cryptococcus gattii species complex

  • “/” means “divided with”.
  • “-“ has three meanings.
    • A hyphen used to join two words to form a compound term.

Example: NPU29141 Urine—2–ethyl–5-methyl-3,3-diphenylpyrroline; arbitrary concentration(procedure) = ?

    • An en dash used to show range or between

Example: NPU10444 Urine—17-Hydroxycorticosteroid; amount-of-substance(0-1 day after challenge) = ? µmol

    • A minus sign used to show a difference

Example: NPU03815 Extracellular fluid—Base excess; substance concentration(actual–norm) = ? mmol/L

  • “[ ]” states a range of a particular amino acid sequence or the isotope of a substance.

Reference
  1. Ferard G, Dybkaer R, Fuentes-Arderiu X. Compendium of Terminology and Nomenclature of Properties in Clinical Laboratory Sciences : Recommendations 2016. 1 ed: Royal Society of Chemistry; 2016. 182 p.
  2. Olesen H. Properties and units in the clinical laboratory sciences. I. Syntax and semantic rules (recommendation 1995). International Union of Pure and Applied Chemistry (IUPAC) and International Federation of Clinical Chemistry (IFCC). Eur J Clin Chem Clin Biochem. 1995;33(9):627-36.

Principles
  1. A unique NPU definition will never be deleted but may become obsolete
  2. Terms (words) in a string can be changed in a NPU definition if the concept is the same and only the terms have changed
  3. A new NPU definition needs to be established if a concept in the NPU definition has changed
  4. Eldest NPU definition remains, youngest becomes obsolete

Examples of principle 1

A NPU definition may become obsolete, if:

  • A doublet (same NPU definition with a different unique identifier) exists
  • A concept in the NPU definition has no clear definition (either international or a internal NPU terminology definition) or has changed (e.g.

Examples of principle 2

  

Examples of principle 3

  

Reference

  

Synonym

 Serial number, code

Scope

 A unique NPU definition can be identified by one unique identifier, national or international

International unique identifier

The International unique identifier consists of three letter abbreviation, NPU (Nomenclature on Properties and Units) and 5 digits

The identifier indicates that the NPU definition can be used in any country

Example:

NPU02319 Blood—Haemoglobin(Fe); substance concentration = ? mmol/L

National unique identifier

The national unique identifier consists of three letter country code, according to ISO 3166-1, and 5 digits.

Examples:

  • DNKxxxxx
  • NORxxxxx
  • SWExxxxx

Note: National codes can have same digits, e.g. DNK12345, NOR12345 and SWE12345, but have different definitions.

Reference
  1. Olesen H. Properties and units in the clinical laboratory sciences. I. Syntax and semantic rules (recommendation 1995). International Union of Pure and Applied Chemistry (IUPAC) and International Federation of Clinical Chemistry (IFCC). Eur J Clin Chem Clin Biochem. 1995;33(9):627-36.
  2. Ferard G, Dybkaer R, Fuentes-Arderiu X. Compendium of Terminology and Nomenclature of Properties in Clinical Laboratory Sciences : Recommendations 2016. 1 ed: Royal Society of Chemistry; 2016. 182 p.