Not within spitting distance: salivary immunoassays of estradiol have subpar validity for predicting cycle phase

Abstract

Salivary steroid immunoassays are widely used in psychoneuroendocrinology to investigate the psychological effects of menstrual cycle phase. Though manufacturers advertise their assays as suitable, they have not been rigorously validated for this purpose. We collated data from eight studies across more than 1,200 women and more than 9,500 time points. All studies measured estradiol and progesterone and had at least one independent indicator of cycle phase (day in cycle relative to the luteinising hormone surge or a menstrual onset). Seven studies collected saliva; one study collected serum. In serum, all non-steroid cycle phase measures strongly predicted steroids in the expected manner. By contrast, salivary immunoassays of estradiol were only weakly predictable from cycle phase and showed an upward bias compared to expectations from serum. For salivary immunoassays of progesterone, predictability from cycle phase was more mixed, but two widely used assays performed poorly. Imputing average serum steroid levels from cycle phase may yield more valid values than several widely used salivary immunoassays. Tandem mass spectrometry may provide a valid alternative to widely used immunoassays and could be combined with imputation.

Is pathogen disgust increased on days of the menstrual cycle when progesterone is high? Evidence from a between-subjects study using estimated progesterone levels

“…These values were imputed separately for the forward-counting and backward-counting methods. Arslan et al (2022) have previously demonstrated that estradiol and progesterone values imputed in this way using the forward-and backward-counting methods are highly correlated with values measured from serum (progesterone: r = .83 or .87, respectively; estradiol: r = .68 or .72, respectively). By contrast, Arslan et al (2022) reported that correlations between values from salivary immunoassays and from serum were substantially weaker.…”

“…For each woman, the date of their last menses and the date for their next menses were used to calculate cycle day using both the backward-counting method and the forward-counting method. Cycle-day data were then used to impute progesterone and estradiol levels using an algorithm described in (and developed by) Arslan et al (2022). These values were imputed separately for the forward-counting and backward-counting methods.…”

“…Jones et al (2018) tested whether 357 women's scores on the pathogen disgust subscale of the Three Domain Disgust Scale (Tybur et al, 2009) increased on days of the menstrual cycle where progesterone was high, finding no evidence that pathogen disgust tracked changes in progesterone. However, progesterone was measured from saliva samples via immunoassays, which is a method that has recently been criticised for having relatively modest validity when measuring changes in progesterone level during the menstrual cycle (Arslan et al, 2022). To address this potential limitation, Stern and Shiramizu (2022) tested whether 257 women's scores on the pathogen disgust subscale of the Three Domain Disgust Scale and scores on the contamination subscale of the Revised Padua Obsessive-Compulsive Inventory (Burns et al, 1996) increased on days of the menstrual cycle where progesterone was high when liquid chromatography mass spectrometry was used to measure progesterone level from saliva.…”

“…Given (1) the mixed evidence for the Compensatory Prophylaxis Hypothesis reported in the longitudinal studies described above and (2) the recent suggestion that carryover effects when pathogen disgust is assessed repeatedly in longitudinal studies might obscure progesterone-linked changes in pathogen disgust (Bressan & Kramer, 2022), the current study used a between-subjects design to test for a positive relationship between scores on the pathogen disgust subscale of Tybur et al's (2009) Three Domain Disgust Scale and progesterone levels imputed from menstrual cycle data using a method described in Arslan et al (2022).…”

Relationships of the Ulna-to-fibula Ratio to Baseline and Reactive Steroid Hormone Levels: An Exploratory Study

“…Salivary hormone radioimmunoassays like those used in our study were our method of choice due to the availability of funding and a specialized lab at our institution. Immunoassays, including radioimmunoassays, were criticized for yielding results inferior to other methods like serum analysis or tandem mass spectrometry, and seem to have low validity for example for estimating menstrual cycle phase (see empirical comparison of assessment methods by Arslan et al, 2022). Nevertheless, problems with measurement validity have been studied more intensively for enzymatic immunoassays (e.g., Welker et al, 2016b;see Chafkin et al, 2022, for an expansion of this work to chemiluminescent immunoassays, which seem to overestimate testosterone and cortisol and suppress testosterone sex differences when compared to LC-MS/MS).…”