>From Wikipedia (see below). Dan
http://en.wikipedia.org/wiki/International_unit International Unit In pharmacology, international unit measures biological activity, or effect, of a substance. It is abbreviated as IU, as UI (French unité internationale or Italian unità internazionale), or as IE (German Internationale Einheit). It is used to quantify vitamins, hormones, some medications, vaccines, blood products, and similar biologically active substances. IU has the advantage over a measure of mass, as milligram (mg), in being consistent in nominal quantity across various forms of a biological agent (as vitamin A in the form of retinol or beta-carotene). Despite its name, IU is not part of the International System of Units used in physics and chemistry. In order to remove the possibility of having the letter: "I" confused with the digit: "1", some hospitals have it as a stated policy to omit the "I", that is: to only use U or E when talking and writing about dosages, while other hospitals avoid the ambiguity all-together by requiring the word "Units" to be written out entirely. Equality and equivalency of IU for different substancesMolecules that are chemically well-defined can be measured in Molar or mass units. However, immunoassays of analytes with structural diversity are not so straightforward. The goal in setting the standard is that different substances with the same biological effect will contain the same number of IUs. For example, rather than specifying the precise types and masses of vitamin E in a mixture, it is sufficient to simply specify the number of IUs of vitamin E. To define the IU for a substance, an international collaborative study is organized by the WHO Expert Committee on Biological Standardization using various assay systems in several laboratories.[1] The main goal of the study is to reach an arbitrary consensus regarding methods of analysis and the approach to standardization to enable commutability of results.[2][3][4] The study is performed using highly purified preparations of the substance, typically in lyophilized form, called "international reference preparations" or IRPs.[1] Each preparation is divided into precisely weighed samples, with each sample stored in its own ampoule labeled with a code corresponding to the source IRP.[1] Assays are performed using these samples and are calibrated against the previously available IU standard. These results can be quite variable; the final IU value for samples of a given IRP are determined by consensus.[2] The IRP that provides the best results and shows the best long term stability is selected to define the next IU.[1] This IRP is then referred to as the "international standard."[1] Since the number of IUs contained in a new substance is arbitrarily set, there is no equivalence between an IU measurement between two dissimilar biological agents. For instance, one IU of vitamin E cannot be equated with one IU of vitamin A in any way, including mass and efficacy. Mass equivalents of 1 IUInsulin: 1 IU is the biological equivalent of about 45.5 μg pure crystalline insulin (1/22 mg exactly). This corresponds to the old USP insulin unit, first suggested by Frederick Banting et.al. in 1922,[5] where one unit (U) of insulin is equal to the amount required to reduce the concentration of blood glucose in a fasting rabbit to 0.045 per cent (45 mg/dL or 2,5 mmol/L) within 4 hours. Vitamin A: 1 IU is the biological equivalent of 0.3 μg retinol, or of 0.6 μg beta-carotene in the USA,[6] and in Canada [7] Vitamin C: 1 IU is 50 μg L-ascorbic acid Vitamin D: 1 IU is the biological equivalent of 0.025 μg cholecalciferol/ergocalciferol Vitamin E: 1 IU is the biological equivalent of about 0.667 mg d-alpha-tocopherol (2/3 mg exactly), or of 1 mg of dl-alpha-tocopherol acetate Difference from unit of enzyme activityThe IU should not be confused with the enzyme unit, also known as the International unit of enzyme activity and abbreviated as U. Dan On Wed, Jun 29, 2011 at 10:51 AM, Kathy Tankersley <babychicks...@gmail.com> wrote: > > Can anyone tell me the difference between UI and gm on vitamins, medicine, > etc? > Thanks, Kathy -- The Silver List is a moderated forum for discussing Colloidal Silver. Rules and Instructions: http://www.silverlist.org Unsubscribe: <mailto:silver-list-requ...@eskimo.com?subject=unsubscribe> Archives: http://www.mail-archive.com/silver-list@eskimo.com/maillist.html Off-Topic discussions: <mailto:silver-off-topic-l...@eskimo.com> List Owner: Mike Devour <mailto:mdev...@eskimo.com>
