Establishing Quantitative Diagnostic Standards for Endometriosis Using Menstrual Blood
Abstract
Purpose
To determine a metabolite profile in menstrual blood that indicates endometriosis. This profile is used to establish quantitative diagnostic standards for endometriosis by analysing the metabolite profiles of 1H NMR spectra of menstrual blood.
Methods
Menstrual blood samples were collected from healthy controls and patients with laparoscopically confirmed endometriosis during days 1–6 of the menstrual cycle. Samples were centrifuged to isolate serum, followed by cold methanol precipitation to remove proteins and macromolecules. The resulting supernatant was lyophilised and reconstituted in a deuterated buffer containing a concentration standard to enable quantitative analysis. One-dimensional 1H NMR spectroscopy was used to identify and quantify inflammatory metabolites selected as prospective biomarkers. Biomarker peak intensities and concentrations were compared between control and endometriosis cohorts. Statistical modelling, including regression and receiver operating characteristic (ROC) analysis, was used to relate biomarker profiles to endometriosis presence and severity, with lesion mass from laparoscopy used as a reference standard.
Results
Examination of spectra indicated a profile of metabolites including alanine, glutamine, tyrosine and 3-hydroxybutyrate fulfilled the criteria of approximately double the serum abundance compared to venous blood leading to visibility using NMR as well as having little correlation with confounding conditions that have similar symptoms during the menstrual phase to endometriosis. These metabolites also had distinct ranges of concentration in menstrual blood between control and endometriosis samples.
Conclusion
This work demonstrates potential for developing a quantitative diagnostic standard for endometriosis using non-invasive methods by analysing menstrual blood. Ranges for the concentration of select biomarkers in menstrual blood were determined and supported by previous studies that have explored NMR-based diagnosis using venous blood during the menstrual phase (with scaled concentration). By employing large-scale metabolite profile data collection of NMR spectra of people with and without endometriosis, improvement can be made in intrusiveness and speed of diagnosis.