Threshold substance concentration (threshold subst.c.) - Dynamic NPU Manual

Threshold substance concentration (threshold subst.c.)


Threshold subst.c.

Definition in words

Lowest value of substance concentration of component B in system 1 to stimulate a specific reaction

Note 1: “Threshold is a modifier indicating that the kind-of-property is defined as the lowest value of a property eliciting a reaction given by the component and specified by the procedure” (Ref 1)

Note 2: The “specified reaction” must be described somewhere else than in the NPU syntax

Definition by equation

Systematic terms

Threshold mass concentration of component B in system 1

Result type

Rational scale
  • Value sets are positive numerical values
  • Algebraic operations are allowed (a=nb; a≠nb)
Numerical values from 0-∞


µmol/L, mmol/L, mol/L etc.


  1. Blombäck, M., René Dybkær, K. Jørgensen, et al. 2009. Properties and units in the clinical laboratory sciences V. Properties and units in thrombosis and haemostasis (Technical Report). Pure and Applied Chemistry. 69(5): 1043-1080. Retrieved 13 Sep. 2019, from doi:10.1351/pac199769051043
  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. Doi:10.1039/9781782622451.

Laboratory field


Clinical Microbiology

Example 1
Generic abbreviated
NPU13569 Syst—Tobramycin; threshold subst.c. = ? µmol/L
Full result NPU13569 System—Tobramycin; threshold substance concentration = 1.4 micromol per liter
Abbreviated result NPU13569 Syst—Tobramycin; threshold subst.c. = 1.4 µmol/L
Written expression The threshold substance concentration of Tobramycin in Mrs. Smith’s system is [1.4] µmol/L.

  1. The NPU code is a context-dependent code (see microbiological structure)
  2. The context-dependent code is attached a list code, in which the system and reaction are specified.

Thrombosis and Haemostasis

Example 2
Generic abbreviated
NPU01109 Trcs(B)—Aggregation, arachidonate-induced; threshold subst.c.(proc.) = ? µmol/L
Full result NPU01109 Thrombocytes(Blood)—Aggregation, arachidonate-induced; threshold substance concentration(procedure) = 25 micromol per liter
Abbreviated result NPU01109 Trcs(B)—Aggregation, arachidonate-induced; threshold subst.c.(proc.) = 25 µmol/L
Written expression The threshold substance concentration of Arachidonate inducing aggregation by Thrombocytes in Mr. Smith’s Blood is [25] µmol/L. The measurement is performed by a procedure defined by the laboratory.


NPU database, and
  • Kind-of-property

    • Nominal kind-of-property

    • Kind-of-quantity

      • Unitary kind-of-quantity

        • Rational unitary kind-of-quantity

          • Threshold substance concentration


  • Dybkaer R. Concept system on ‘quantity’: formation and terminology. Accredit Qual Assur. 2013;18(3):253-60.
  • Dybkaer R. ISO terminological analysis of the VIM3 concepts ‘quantity’ and ‘kind-of-quantity’. Metrologia. 2010;47(3):127-34.
Date Term Note
1996-01-01 Threshold substance concentration Term established