Characterization of Salivary Progesterone in Female Smokers.

INTRODUCTION: Fluctuations in ovarian hormones have been associated with changes in cigarette smoking behavior, which can be measured through both serum or less invasive salivary procedures. The primary aim of this exploratory study is to characterize the progesterone profiles of salivary progesterone measurements and to compare that with the profiles estimated from a previously measured serum sample. AIMS AND METHODS: Nontreatment-seeking, cigarette smoking women (n = 82; ages 18-45 years) provided daily salivary hormone samples every morning for 14 consecutive days. Time-dependent random effects functions were used to approximate daily salivary progesterone (ng/mL) levels over the course of a standardized menstrual cycle. Serum measures of progesterone from a previous study of female cigarette smokers were examined for consistency with established profiles and compared with the salivary profile using the same methodology. RESULTS: The salivary model fit exhibits relative stability during the follicular phase and a clear unimodal peak during the luteal phase. Parameter estimates from the non-linear function show correspondence to serum data. Although the profiles estimated from salivary and serum data agree in functional form, we observed larger between-subject heterogeneity both in the follicular level and the peak luteal level in salivary measures. CONCLUSIONS: The pattern of salivary and serum progesterone measured across the menstrual cycle is similar in form, which is noteworthy given that the saliva and serum samples were drawn from independent sample of female smokers. Inter- and intra-individual variation in salivary measures may be greater than in serum measures. IMPLICATIONS: Measuring progesterone level variation across the menstrual cycle via saliva samples has several benefits relative to serum sampling methods in that they are easily obtained, noninvasive, and low-cost. Inter- and intra-individual variation in measurements may be greater than those in serum measurements. However, the functional form of the salivary progesterone profile is isomorphic to serum progesterone.