[Problems and perspectives of wider use of saliva for diagnostic purposes]

Saliva of individual salivary glands differs in appearance, density and particularly in the chemical composition. Generally, the composition of saliva is affected by the composition of blood plasma, salivary flow rate, hormonal activity, drug administration, smoking and other physiological and pathophysiological states of the organism. In spite of these facts, many of the components are permanently present in saliva (e.g. peptides, enzymes, hormones...) only their concentrations vary. In some special cases unusual constituents can be detected in the saliva as legal and illegal drugs, antibodies (HIV), and abnormal bacteria or viruses. When there is good correlation between the levels of constituents in saliva and blood plasma then the determination of the constituent level in saliva can be used for diagnostic and/or monitoring purposes. But the main advantage of saliva analysis resides in stress-free and harmless collection of saliva in comparison with blood withdrawing. However, the use of saliva for diagnostic purposes is still at its beginning. So far, only few such applications are known, but optimists believe that the saliva analysis has a very prospective chance to substitute or alternate the biochemical analysis of blood plasma due to the mentioned advantage and to attribute more information on the processes in the human body. (Fig. 1, Ref. 16.)