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International Unit
Pronunciation
Definition 1
A unit used to measure the activity of many vitamins, hormones, enzymes, and drugs. An International Unit is the amount of a substance that has a certain biological effect. For each substance there is an international agreement on the biological effect that is expected for 1 International Unit. Also called IU. (NCI Dictionary)
Definition 2
International unit. A unit of measurement based on the International System of Units. This system defines units to measure length, time, mass, electric current, temperature, light intensity, and the amount of a substance. It can be used to express measurements of fat-soluble vitamins and some hormones, enzymes, and drugs. (NCI Dictionary)
Definition 3
The unitage assigned by the WHO to International Biological Standards - substances, classed as biological according to the criteria provided by WHO Expert Committee on Biological Standardization (e.g. hormones, enzymes, and vaccines), to enable the results of biological and immunological assay procedures to be expressed in the same way throughout the world. The definition of an international unit is generally arbitrary and technical, and has to be officially approved by the International Conference for Unification of Formulae. (NCI Thesaurus)