Threshold mass concentration (threshold mass c.) - Dynamic NPU Manual

Threshold mass concentration (threshold mass c.)


Threshold mass c.

Definition in words

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

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


µg/L, mg/L, g/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
NPU54391 Syst—Metronidazole; threshold mass c. = ? mg/L
Full result NPU54391 System—Metronidazole; threshold mass concentration = 4 milligram per liter
Abbreviated result NPU54391 Syst—Metronidazole; threshold mass c. = 4 mg/L
Written expression The threshold mass concentration of Metronidazole in Mr. Smith’s blood is [4] mg/L.

  1. “System” is specified by the laboratory
  2. The NPU code is established according to the microbiological structure within the NPU terminology.
  3. The NPU code is a  context-dependent code (see microbiological structure)
  4. The specified reaction can e.g. be minimal inhibitory concentration (MIC). The laboratory must specify this somewhere else than in the NPU code.

Thrombosis and Haemostasis

Example 2
Generic abbreviated
NPU01113 Trcs(B)—Aggregation, ristocetin-induced; threshold mass c.(proc.) = ? g/L
Full result NPU01113 Thrombocytes(Blood)—Aggregation, ristocetin-induced; threshold mass concentration(procedure) = 1.01 gram per liter
Abbreviated result NPU01113 Trcs(B)—Aggregation, ristocetin-induced; threshold mass c.(proc.) = 1.01 g/L
Written expression The threshold mass concentration of Thrombocytes’ Aggregation, ristocetin-induced in Mr. Smith’s blood is [1.01] g/L. The measurement is performed according to 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 mass 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 mass concentration Term established