Determinants of attained estradiol levels in response to oral estradiol plus progesterone therapy

Assessing estrogen exposure from transdermal estradiol patch therapy using a dried urine collection and a GC-MS/MS assay

BACKGROUND

Transdermal estradiol patch therapy is often dosed based on patient reported symptoms. Although dosing based on serum estradiol concentrations has been considered, serum sampling is too invasive and inconvenient to use in real-world settings. The primary aim of this study was to determine if a dried urine assay could be used to assess estrogen exposure resulting from transdermal estradiol patch therapy at increasing doses.

METHODS

This was a retrospective analysis of clinical laboratory data. Urinary estrogen profiles of postmenopausal women being treated with transdermal estradiol patches at differing doses (age = 56.8 ± 7.5) were selected from the database along with the profiles of women on no therapy for comparison (age = 55.1 ± 9.5). Metabolite concentrations were obtained using a multi-spot dried urine collection and a gas chromatography-tandem mass spectrometry assay. The Jonckheere-Terpstra test was used to assess for ordered differences across dose groups to determine if dose-dependent increases in urinary estrogens occurred with increasing doses.

RESULTS

Median concentrations of estradiol and other estrogen metabolites increased with increasing doses of transdermal estradiol patch therapy (p < 0.001; Jonckheere-Terpstra test). For women who collected samples before and after initiating therapy, there were significant differences between before and after concentrations of estradiol and other estrogen metabolites.

CONCLUSION

This large study conducted using real-world data demonstrated that a dried urine assay offers a viable method of assessing estrogen exposure differences that occur with the use of differing doses of transdermal estradiol patches. Further studies with prospective designs that include outcome measures are needed to confirm the findings of this study.

Assessment of estrogen exposure from transdermal estradiol gel therapy with a dried urine assay

Transdermal estradiol gel is a commonly used menopausal hormone therapy. In research studies investigating the pharmacokinetics and clinical utility of transdermal estradiol gels, serum is often used to measure estradiol levels. Serum results only represent a moment in time during phlebotomy and thus provide little information and allow for limited inference unless serial measurements are performed. In contrast, dried urine may provide a representation of serum estradiol levels over a longer period of time, while also being non-invasive and easier to collect. The primary aim of this study was to evaluate a dried urine method to determine if it may be a viable option for evaluating estrogen exposure resulting from transdermal estradiol gel use. A secondary aim was to explore differences in the urinary estrogen profiles of premenopausal women on no therapy and postmenopausal women who were either on transdermal estradiol gel therapy or no therapy at all. The results of this study demonstrated that the expected dose-proportional changes in estrogen exposure can be observed in the urinary estrogen profile using a GC-MS/MS dried urine assay. The GC-MS/MS assay also showed the differences in the urinary estrogen profiles of premenopausal women, postmenopausal women on estrogen replacement therapy, and postmenopausal women on no therapy.