On Sunday 06 January 2008 16:52, [EMAIL PROTECTED] wrote: > I didn't know doctors were still prescribing in IUs (see article below). > > An excellent reason (as Paul has pointed out in the past) for > standardizing on SI.
The IUs (they are substance-specific units, so plural) are used for chemicals with variations. Vitamin E, for instance, can be any of several tocopherols or a mixture of them. The IU of vitamin E is specified as a procedure for measuring its antioxidantness and a definition that 2/3 mg of one of those tocopherols is 1 IU. Specifying the amount of vitamin E in milligrams would be wrong, unless you specify the particular tocopherol. So would specifying it in katals, as it's not a catalyst. > For example, "TOF" could be taken to mean "tetralogy of fallot" or > "tracheo-oesophageal fistula" - two completely different conditions. A tetralogy is a series of four stories, and I never heard of "fallot". Is that supposed to be "teratology of fallout" (monster resulting from radioactivity)? (The other one is an abnormal hole between the windpipe and the gullet.) Pierre
