Changes in Exhaled Carbon Dioxide during the Menstrual Cycle and Menopause

Abstract

Introduction: The menstrual cycle (MC) reflects multifaceted hormonal changes influencing women’s metabolism, making it a key aspect of women’s health. Changes in hormonal levels throughout the MC have been demonstrated to influence various physiological parameters, including exhaled carbon dioxide (CO<sub>2</sub>). Lumen is a small handheld device that measures metabolic fuel usage via exhaled CO<sub>2</sub>. This study leverages exhaled CO<sub>2</sub> patterns measured by the Lumen device to elucidate metabolic variations during the MC, which may hold significance for fertility management. Additionally, CO<sub>2</sub> changes are explored in menopausal women with and without hormonal replacement therapy (HRT). Methods: This retrospective cohort study analyzed exhaled CO<sub>2</sub> data from 3,981 Lumen users, including eumenorrheal women and menopausal women with and without HRT. Linear mixed models assessed both CO<sub>2</sub> changes of eumenorrheal women during the MC phases and compared between menopausal women with or without HRT. Results: Eumenorrheic women displayed cyclical CO<sub>2</sub> patterns during the MC, characterized by elevated levels during the menstrual, estrogenic and ovulation phases and decreased levels during post-ovulation and pre-menstrual phases. Notably, despite variations in cycle length affecting the timing of maximum and minimum CO<sub>2</sub> levels within a cycle, the overall pattern remained consistent. Furthermore, CO<sub>2</sub> levels in menopausal women without HRT differed significantly from those with HRT, which showed lower levels. Conclusion: This study reveals distinct CO<sub>2</sub> patterns across MC phases, providing insights into hormonal influences on metabolic activity. Menopausal women exhibit altered CO<sub>2</sub> profiles in relation to the use or absence of HRT. CO<sub>2</sub> monitoring emerges as a potential tool for tracking the MC and understanding metabolic changes during menopause.