Attenuance - Dynamic NPU Manual


Definition in words

Negative decadig logarithm of internal transmittance of a parallel beam of a rediation through that medium (system 1)

Definition by equation

Systematic terms

Attenuance of system 1

Result type

Logarithmic scale
  • Value sets are numerical values on a base 10 logarithmic scale
  • Values cannot be divided or multiplied (a-b=c-d; a-b≠c-d)
Numerical values 0 to ∞


One (1)

Note: Absorbance unit is discouraged

Non-recommended term

Extinction, optical density, optical transmission density, transmission density,


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
NPU27959 Csf—Cerebrospinal fluid; attenuance(415 nm; UKNEQAS 2008) = ?
Full result NPU27959 Cerebrospinal fluid—Cerebrospinal fluid; attenuance(415 nm; UKNEQAS 2008) = 0.17
Abbreviated result NPU27959 Csf—Cerebrospinal fluid; attenuance(415 nm; UKNEQAS 2008) = 0.17
Written expression The attenuance of Mr. Smith’s cerebrospinal fluid is [0.17]. The measurement is obtained at 415 nm by a procedure defined by UK NEQAS guidelines from 2008.


NPU database, and

Cruickshank, A., Auld, P., Beetham, R., Burrows, G., Egner, W., Holbrook, I., … White, P. (2008). Revised national guidelines for analysis of cerebrospinal fluid for bilirubin in suspected subarachnoid haemorrhage. Annals of Clinical Biochemistry, 45(3), 238–244.

Beetham, R., Egner, W., & Patel, D. (2011). The UKNEQAS scheme for cerebrospinal fluid haem pigments: a paradigm for service improvement. Annals of Clinical Biochemistry, 48(6), 489–497.

  • Kind-of-property

    • Nominal kind-of-property

    • Kind-of-quantity

      • Unitary kind-of-quantity

        • Rational unitary kind-of-quantity

          • Attenuance


  • 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
2010-03-22 Attenuance Term established