Estradiol in saliva for monitoring follicular stimulation in an in vitro fertilization program.

A rapid and sensitive radioimmunoassay (RIA) was developed to compare serum and saliva estradiol (E2) levels in patients undergoing ovulation induction in an in vitro fertilization and embryo transfer (IVF-ET) program. Serum and saliva E2 were compared in 23 patients. The sensitivity of the saliva RIA standard curve was 11 fmol/tube (equal to 3.2 pg/tube). There was a highly significant correlation between serum and saliva E2 throughout the stimulated cycles (r = 0.769; P less than 0.001). The ratio of serum to saliva E2 was constant throughout the stimulated cycles (1.7% +/- 0.3%, mean +/- standard deviation [SD]). The E2 concentration per follicle was 1548 pmol/l in serum and 23 pmol/l in saliva. Mean E2 levels in saliva (+/- SD) were 74 +/- 21 pmol/l at midcycle and 46 +/- 12 pmol/l at midluteal phase. The findings indicate that measurement of saliva E2 provides a reliable, noninvasive method and may replace serum measurements for monitoring stimulated cycles in an IVF-ET program.