Abbreviations and symbols, used throughout the text as essential space savers, are shown in Abbreviations. Other abbreviations in the text are expanded at the first mention in the topic.

Laboratory values are given in conventional units. In most cases, however, SI units follow in parentheses.

Drugs are designated by generic (nonproprietary) names, but scrolling the mouse cursor over a drug name in the text will bring up some trade names for that drug, as well as an option to obtain in-depth information about that drug. Also many of the drugs mentioned in the text are listed in Trade Names of Some Commonly Used Drugs, with each generic term followed by one or more trade names.

Note: The contents of this web site originated as the 18^th edition of The Merck Manual of Diagnosis and Therapy; however the topics are updated regularly to add the latest clinical information and thus may deviate from the print edition. Each topic page displays the date it was last reviewed and revised.

Last full review/revision February 2010