IU (international unit)

An international unit (IU) is an internationally accepted amount of a substance. This type of measure is used for the fat-soluble vitamins (such as vitamins A, D and E) and certain hormones, enzymes, and biologicals (such as vaccines). The definition of an international unit (IU) is generally arbitrary, technical, and eminently forgettable. For example, an IU of vitamin E is the specific biological activity of 0.671 milligrams of d-alpha-tocopherol. Nonetheless, most IUs are quite handy and helpful in use as a means of standardizing measures. All international units are officially defined by the International Conference for Unification of Formulae.

Medical dictionary. 2011.

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  • international unit — n the amount of specific physiological activity of a standardized preparation (as of a vitamin) that is agreed upon as an international standard esp. for comparison with other biologicals containing the substance in impure form or with a related… …   Medical dictionary

  • International unit — In pharmacology, the International Unit is a unit of measurement for the amount of a substance, based on biological activity or effect. It is abbreviated as IU, as UI (Spanish unidad internacional or French unité internationale or Italian unità… …   Wikipedia

  • international unit — Pharm. 1. an internationally agreed upon standard, as measured by bioassay, to which samples of a substance, as a drug or hormone, are compared to ascertain their relative potency. 2. the particular quantity of such a substance, which causes a… …   Universalium

  • international unit — noun A particular, minute unit of mass, defined differently for different substances, but so that varying substances of the same general type have the property that one international unit of the one has the same effect on the human body as one… …   Wiktionary

  • international unit — tarptautinis vienetas statusas T sritis fizika atitikmenys: angl. international unit vok. internationale Einheit, f rus. международная единица, f pranc. unité internationale, f …   Fizikos terminų žodynas

  • international unit — (IU)    a unit used to measure the activity (that is, the effect) of many vitamins and drugs. For each substance to which this unit applies, there is an international agreement specifying the biological effect expected with a dose of 1 IU. Other… …   Dictionary of units of measurement

  • international unit of vitamin A — an older unit of vitamin A activity, equal to the activity of 0.3 microgram retinol or 0.6 microgram β carotene; because the provitamin A carotenoids are absorbed less efficiently than is retinol, the source must be specified. Although… …   Medical dictionary

  • International Unit — IU. A unit used to measure the activity of many vitamins, hormones, enzymes, and drugs. An IU 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… …   English dictionary of cancer terms

  • international unit — noun a unit of activity for a particular vitamin, hormone, etc. in terms of the activity of a standard quantity …   English new terms dictionary

  • international unit — /ɪntəˌnæʃnəl ˈjunət/ (say intuh.nashnuhl yoohnuht) noun a unit of the amount of a biologically active substance, such as a vitamin or hormone, required to produce a specific response …   Australian English dictionary

  • international unit — noun Date: 1922 a quantity of a biologically active substance (as a vitamin) that produces a particular biological effect agreed upon as an international standard …   New Collegiate Dictionary

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