"What tests do I order, and what do the results mean?" This book provides the answers for a vast range of adult and pediatric conditions. Arranged by organ system, the book summarizes the available tests for most diseases, explains what the results mean, and discusses differential diagnoses. Includes additional tests based on molecular biology, new data on the use of genetic tests, and many new diagnostic laboratory tests in chemistry. Imaging tests are included where they play a key role in diagnosis. The section on chemical and microbiological terrorism has been expanded.