Ultrafiltrate of saliva collected in situ for the measurement of testosterone

Abstract

A device for the in situ collection of an ultrafiltrate of saliva was investigated. The collector consists of an osmotic pump that, when placed in the mouth, accumulates a prepurified salivary filtrate within a few minutes. The concentration of testosterone in saliva and in the ultrafiltrate from five male subjects was determined by a solid-phase immunoassay. The ultrafiltrate can be used without extraction as a medium for the diagnostic evaluation of free, protein-unbound testosterone. Concentrations in whole saliva and the ultrafiltrate correlate closely (r = 0.89; n = 42). The collector can potentially be used for the measurement of a wide variety of analytes other than testosterone. An ultrafiltrate of saliva as diagnostic medium provides the following advantages: simplicity of collection; moderate stimulation of salivary flow; exclusion of potential blood contamination; prevention of binding of analytes to protein; prevention of potential metabolic degradation of analytes; reduction of viscosity by exclusion of mucopolysaccharides and other large molecules; and potential sterile sampling of ultrafiltrate.