Comparing 17β-estradiol and progesterone concentrations in young, physically active females: Insights from plasma versus serum analysis

Authors

Samantha N. Rowland, Loughborough University
Mariasole Da Boit, De Montfort University
Rachel Tan, Pepperdine University
Liam M. Heaney, Loughborough University
Stephen J. Bailey, Loughborough University

Department(s)

Natural Science

Document Type

Article

Version Deposited

Published version

Publication Date

1-30-2025

Keywords

contraception, hormones, immunoassay, menstrual cycle, physiology

Abstract

Serum measurements of 17β-estradiol and progesterone are widely used to verify menstrual cycle status and confirm contraceptive use, often through commercially available immunoassay kits. However, no studies have investigated whether blood collection tube chemistries influence hormone concentrations in young females, despite assays permitting the use of different biofluids with similar reference ranges. In this study, venous blood was sampled from physically active females (n = 25) using Ethylenediaminetetraacetic acid (EDTA) and serum vacutainers, and 17β-estradiol and progesterone concentrations were measured using competitive immunoenzymatic assays. Median plasma concentrations of 17β-estradiol and progesterone were 44.2% (plasma 40.75 vs. serum 28.25 pg/ml) and 78.9% (plasma 1.70 vs. serum 0.95 ng/ml) higher than serum concentrations, respectively (P < 0.001 for both). Strong positive correlations were observed between plasma and serum concentrations for 17β-estradiol (r = 0.72; P < 0.001) and progesterone (r = 0.89; P < 0.001). The mean bias and limits of agreement for plasma versus serum were 12.5 pg/ml (−20.6 to 45.5 pg/ml) for 17β-estradiol and 1.01 ng/ml (−5.6 to 7.6 ng/ml) for progesterone. Ovarian hormone levels were consistently higher in EDTA plasma compared with serum, with these matrices not yielding statistically equivalent results. Despite these differences, the strong correlations and good agreement suggest that both matrices are suitable for biomarker analysis. Researchers using EDTA plasma should account for the higher hormone concentrations when applying inclusion or exclusion criteria, because adjustments might be necessary to ensure appropriate participant classification.

Publication Title

Experimental Physiology

ISSN

09580670

E-ISSN

1469445X

DOI

10.1113/EP092415

Comments

Publication can be accessed at this link: https://10.1113/EP092415

Recommended Citation

Rowland SN, Da Boit M, Tan R, Heaney LM, Bailey SJ. Comparing 17β-estradiol and progesterone concentrations in young, physically active females: Insights from plasma versus serum analysis. Exp Physiol. 2025 Mar 12. doi: 10.1113/EP092415. Epub ahead of print. PMID: 40077907.