Endocrine Abstracts

JOINT657

Oestrogen analysis presents a significant challenge due to the low concentrations of these hormones, particularly oestradiol, the most potent oestrogen. Oestrogens plays important roles in fertility, bone health, and various endocrine disorders. Traditional methods for measuring oestrogens, such as immunoassays, are unreliable at low concentrations and prone to high cross-reactivity, leading to inaccurate results and potential misdiagnoses. Mass spectrometry (MS) is as a more selective and sensitive alternative for oestrogen analysis. Unlike immunoassays, MS offers reduced cross-reactivity, enhancing the reliability of hormone measurements. However, quantifying oestrogens remains challenging due to their low concentrations and poor ionization, even when using highly sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) techniques. These methods often require large sample volumes, particularly when measuring in populations such as post-menopausal women, men, and children. Gas chromatography-mass spectrometry (GC-MS) is a viable alternative employing post extraction derivatisation which improves ionizability allowing quantitation of poorly ionising, low concentration oestrogens. Additionally, use of urine permits sample concentration without unacceptable matrix effects associated with serum. Therefore, we developed a GC-MS method for urinary oestrogen profiling for the detection of eleven oestrogens, including oestradiol, oestrone, and their hydroxy and methoxy derivatives. Twenty-four-hour urine samples were collected from 51 healthy females (26 pre-menopausal (age 20-49) and 25 post-menopausal (age 50-76). Steroids were extracted from 2mL of 24-hour urine, deconjugated and derivatised into methyloxime-trimethylsilyl ethers. The oestrogens were measured on a Shimadzu GC-MS-QP2020NX relative to an internal standard and a calibration series to ensure accuracy. Our GC-MS method quantified oestrogens in both pre- and postmenopausal women. The highest concentration oestrogens were oestradiol, median (5^th-95^th percentile) in all (6, 2-34) pre-menopausal (14, 2-34), post-menopausal (4, 1-18), oestriol all, (3, 0. 5-20), pre (6, 1-21) post (2, 0. 7-6), oestrone all (3, 0. 5-30), pre (5 (1-33), post (1, 0. 2-20) and 2-methoxy-oestrone all (8, 3-20) pre (7, 3-20) post (8, 3-17)µg/24hr. All other oestrogens were detectable at median concentrations ranging from 0. 2-1. 7µg/24hr. There were significant differences (Mann-Whitney-U P < 0. 05) in excretion of oestrone, oestradiol, and 2-hydroxyoestrone, when comparing pre and post-menopausal women. There were positive correlations between excretion of oestrone, oestriol and progesterone metabolites whereas excretion of oestradiol correlated with androgen metabolites. GC-MS urinary oestrogen profiling is essential for detecting low oestrogen concentrations, particularly in post-menopausal women and those undergoing treatments such as tamoxifen. Our method demonstrates the sensitivity needed for assessing treatment efficacy in challenging clinical applications.