A large number of tests are widely available. Many tests are specialized for a particular disorder or group of related disorders (which are usually described with the appropriate disorders in this book). Other tests are commonly used for a wide range of disorders.
Resources for Help and Information
This collection of resources is selective and restricted largely to national organizations in the United States, many of which have local chapters. Sites chosen are generally not-for-profit and usually offer information or support rather than advocacy. Telephone numbers and web sites are included as appropriate; however, such information changes frequently. Additional information is available through health care professionals, local libraries, telephone listings, and the Internet.
Weights and Measures
In medicine, precise measurements are necessary—for example, when various substances are measured in laboratory tests to evaluate health or make a diagnosis. Different units of measure may be used depending on the substance. Usually, the metric system, based on multiples of 10, is used to measure the following: