The proposed reference book provides 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 in taking samples on these changes .The directory is distinguished by a logical and easy-to-use logical structure, a developed system of alphabetical indexes, and convenient data search. The book is recommended both for people without medical education and for doctors and other medical professionals.