Arbitrary substance content (arb.subst.cont.) - Dynamic NPU Manual

Arbitrary substance content (arb.subst.cont.)



Definition in words

Arbitrary amount-of-substance of component B divided by mass of system 1

Definition by equation

Note: kprocedure is a constant defined by the measurement procedure (there is an approximately proportionality to a kind-of-quantity from the International System of Quantities).

Result type

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


International unit (IU) or procedure defined unit (p.d.u.) (non-SI units)

Special rule(s) in the NPU syntax

“Procedure” is stated in the specification to the kind-of-property in the NPU definition.

“Procedure” indicates that the measurement procedure must be stated somewhere else than the NPU code and there may be difficulties in comparing values for the same NPU code.

If the ratio scale is attributed to the NPU definition, the unit is a non-SI unit. If the unit is an International Unit (IU), an international certified reference material (e.g. WHO reference material) is specified in the specification to the kind-of-property. If there exist no an international certified reference material, the laboratory can specify the unit at the placeholder, procedure defined unit.


  • 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 Chemistry

Generic abbreviated
NPU56149 Pt—Chorionic Gonadotropin(administered); arb.subst.cont.(i.m.; am.s./body mass; IS 07/364; proc.) = ? IU/kg
Full result NPU56149 Patient—Chorionic Gonadotropin(administered); arbitrary substance content(intramuscular; arbitrary amount-of-substance/body mass; IS 07/364; procedure) = 108 IU/kg
Abbreviated result NPU56149 Pt—Chorionic Gonadotropin(administered); arb.subst.cont.(i.m.; am.s./body mass; IS 07/364; proc.) = 108 IU/kg
Written expression The arbitrary substance content of administered Chorionic Gonadotropin in Mrs. Smith is [108] IU/kg. The procedure is defined by the laboratory. The substance is administrered intramuscular. “IU” is defined and its magnitude by the certified reference material, IS 07/364 from WHO.

  • Kind-of-property

    • Nominal kind-of-property

    • Kind-of-quantity

      • Unitary kind-of-quantity

        • Rational unitary kind-of-quantity 

          • Arbitrary substance content


  • 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 Arbitrary substance content Term established