We all have to undergo medical tests from time to time. The reality is that when we come to the clinic, we most often meet a therapist who hastily writes and does not explain anything, and yet everyone has the right to know why he is taking the test and what the result can tell about. It is also important to know how to properly prepare for the test: improper preparation can seriously affect the result. This book contains complete and up-to-date information about almost all medical tests: general clinical, biochemical, hormonal, immunological and many others. Particular attention is paid to describing the reasons for changes in normal indicators, the influence of diseases, medications, and even errors during analysis on these changes. The directory contains 3 alphabetical indexes that allow you to quickly find the information you need. It will be useful both for people without special education and for medical workers.