Hormones in saliva.

Since the collection of saliva is noninvasive, nonstressful and usually very convenient there have been many recent studies examining the clinical relevance of measuring various hormones in saliva. It now appears that the measurement of most unconjugated steroids in saliva will provide clinically useful data whereas the measurement of conjugated steroids, thyroid hormones, and protein hormones is unlikely to be clinically relevant. The key factors determining whether the salivary concentration of a hormone or drug is likely to be clinically relevant are the mechanisms by which the material enters the saliva; the "free to protein bound" ratio for the material; and the structure of the material, i.e., its molecular weight, polarity and the presence of ionizable groups.