Duration of Menopause, Rather than Primary Hyperparathyroidism Severity, Predicts Osteoporosis in Postmenopausal Women: A Pilot Study from a Spanish Reference Center

<b>Background/Objectives:</b> Osteoporosis is considered a surgical indication in primary hyperparathyroidism (PHPT), regardless of menopausal status. This pilot study aimed to evaluate the impact of menopause and PHPT on bone mineral density (BMD) and to explore additional clinical factors that may influence bone health. <b>Methods:</b> We conducted an observational pilot study including 204 postmenopausal women with osteopenia or osteoporosis who underwent surgery for sporadic PHPT between 2009 and 2021 at Cruces University Hospital (Spain). Demographic data, anthropometric data, date of last menstrual period, years since menopause (YSM), and the clinical history of bone fragility were collected prior to parathyroidectomy. Biochemical parameters and months with hypercalcemia (MHCa)-as a surrogate for PHPT exposure-were analyzed. BMD results were expressed as a densitometric index, the T-Score. <b>Results:</b> Higher age (<i>p</i> = 0.043), greater body mass index (BMI) (<i>p</i> = 0.039), more YSM (<i>p</i> = 0.027), lower serum calcium levels (s-Ca) (<i>p</i> = 0.04), and glucocorticoid treatment antecedents (GcT) (<i>p</i> = 0.029) were all significantly associated with femoral osteoporosis. Similarly, higher weight (<i>p</i> = 0.004), greater MHCa (<i>p</i> = 0.01), lower height (<i>p</i> = 0.01) and s-Ca levels (<i>p</i> = 0.002) were significantly associated with spinal osteoporosis. Furthermore, logistic regression multivariate analysis determined that femur density was independently influenced by YSM (<i>p</i> < 0.001), s-Ca (<i>p</i> = 0.018), BMI (<i>p</i> = 0.002) and GcT (<i>p</i> = 0.006). Osteoporosis of the spine was also independently associated with YSM (<i>p</i> = 0.036), s-Ca (<i>p</i> = 0.031) and also with body weight (<i>p</i> = 0.003). <b>Conclusions:</b> The duration of menopause (YSM), rather than PHPT severity, is an independent predictor of osteoporosis in postmenopausal women.