The role of menopause in the development of chronic mountain sickness

The objective of this study was to investigate the role of menopause in the appearance of the physiopathological sequence that leads to chronic mountain sickness (CMS) in a high-altitude female population. The females studied are 30-54 yr old (n = 152) and have permanent residence in Cerro de Pasco (Pasco, Peru; 4,300 m). The sample was divided into postmenopausal and premenopausal groups for comparison. Blood oxygen saturation (Sa(O₂)), excessive erythrocytosis (EE, measured by the level of hematocrit (Hct)], peak expiratory flow rates (PEFR), and a score that represents the main signs and symptoms of CMS (CMS(score)) were measured. Postmenopausal women had higher Hct (50.2 ± 4.04 vs. 47.4 ± 4.13%, P < 0.001), lower Sa(O₂) (81.9 ± 4.12 vs. 84.7 ± 3.14%, P < 0.001) and PEFR values (489 ± 101 vs. 534 ± 90 l/min, P < 0.02), and slightly higher CMS(score) (19.1 ± 3.37 vs. 17.9 ± 3.48, P < 0.06) than premenopausal women. The prevalence of women with EE (EE - Hct >56%) was found to be 8.8%. Forty-five percent of the postmenopausal subjects presented a high CMS(score) (>21), whereas only 22% of the premenopausal subjects presented this high value (P < 0.02). We can therefore conclude that menopause may represent a contributing factor for the development of CMS.