Metabolic effects of early-onset menopausal transition

The mean age at natural menopause is 51 years, preceded by a gradual decline of ovarian function (climacteric phase). One percent of women, however, experience menopause by the age of 40 (premature ovarian insufficiency, POI), and up to 12% experience menopause by the age of 45 (early menopause, EM). Women with POI are known to be at risk for some adverse health outcomes, especially osteoporosis and cardiovascular diseases, while less is known about the health consequences of EM. For some diseases, like diabetes, the evidence on the association of menopausal status and age at menopause is controversial.

The objective of this study was to investigate health outcomes in women experiencing menopausal transition by their mid-40s, compared to premenopausal women at the same age. The main outcomes were a cardiovascular risk profile, glucose metabolism, vitamin D status and prevalence of thyroid autoantibody positivity and dysfunction. The study population consisted of female participants from the prospective Northern Finland Birth Cohort 1966 (NFBC1966) who participated in the NFBC1966 46-year follow-up study. The 46-year-old participants were divided into two groups—climacteric and preclimacteric—based on their level of follicle-stimulating hormone (FSH) and menstrual anamnesis. The study outcomes were compared between the groups at the age of 46 and some outcomes also at the age of 31.

The study results suggest that early-onset climacteric transition is an independent risk factor for adverse changes in body composition, lipid profile, liver enzymes and insulin sensitivity. The risk for thyroid dysfunctions in climacteric women was also slightly increased, even though the prevalence of thyroid autoantibody positivity did not increase. Interestingly, the use of hormone replacement therapy (HRT) was associated with higher vitamin D status in climacteric women, as the results were adjusted with factors known to be related to vitamin D status. In conclusion, early-onset menopausal transition should be considered a risk factor for adverse health outcomes. Healthy lifestyle habits and the use of HRT may be beneficial in reducing this risk.