Clinical factors affecting salivary transferrin level, a marker of blood contamination in salivary analysis

BACKGROUND: Diagnostic value of whole saliva may be compromised when blood contamination is present in saliva samples. Measuring transferrin level in saliva samples has been used for detecting the level of blood contamination in saliva. The aim of this study was to investigate the validity of transferrin as a proper biomarker for blood contamination in whole saliva. METHODS: Thirty younger (mean age: 25.9 ± 2.1 years) and twenty older (mean age: 65.1 ± 9.0 years) females were included. The index reflecting overall gingival inflammation (total gingival index), salivary flow rate, and salivary concentration and secretion rate of transferrin of each subject were analyzed. RESULTS: Salivary transferrin concentrations and secretion rates were higher in the younger females than in the older ones despite a lower total gingival index in the younger females. The total gingival index showed no significant correlations with the concentration or secretion rate of transferrin in either unstimulated or stimulated whole saliva of younger and older subjects. The salivary concentration of transferrin showed negative correlations with the flow rate of saliva in both the younger and older groups. There were significant positive correlations between the salivary concentrations and secretion rates of transferrin in both the younger and older groups. CONCLUSIONS: Salivary transferrin levels could be affected by other factors as well as the level of blood contamination. The influences of age, gonadal hormones, salivary flow rate, and chewing performance need to be considered when using the salivary level of transferrin as a blood contamination marker.