Global REACH 2018: volume regulation in high-altitude Andeans with and without chronic mountain sickness.

ABSTRACT

The high-altitude maladaptation syndrome known as chronic mountain sickness (CMS) is characterized by polycythemia and is associated with proteinuria despite unaltered glomerular filtration rate. However, it remains unclear if indigenous highlanders with CMS have altered volume regulatory hormones. We assessed NH2-terminal pro-B-type natriuretic peptide (NT pro-BNP), plasma aldosterone concentration, plasma renin activity, kidney function (urinary microalbumin, glomerular filtration rate), blood volume, and estimated pulmonary artery systolic pressure (ePASP) in Andean males without (n = 14; age = 39 ± 11 yr) and with (n = 10; age = 40 ± 12 yr) CMS at 4,330 m (Cerro de Pasco, Peru). Plasma renin activity (non-CMS 15.8 ± 7.9 ng/mL vs. CMS 8.7 ± 5.4 ng/mL; P = 0.025) and plasma aldosterone concentration (non-CMS 77.5 ± 35.5 pg/mL vs. CMS 54.2 ± 28.9 pg/mL; P = 0.018) were lower in highlanders with CMS compared with non-CMS, whereas NT pro-BNP was not different between groups (non-CMS 1394.9 ± 214.3 pg/mL vs. CMS 1451.1 ± 327.8 pg/mL; P = 0.15). Highlanders had similar total blood volume (non-CMS 90 ± 15 mL·kg-1 vs. CMS 103 ± 18 mL·kg-1; P = 0.071), but Andeans with CMS had greater total red blood cell volume (non-CMS 46 ± 10 mL·kg-1 vs. CMS 66 ± 14 mL·kg-1; P < 0.01) and smaller plasma volume (non-CMS 43 ± 7 mL·kg-1 vs. CMS 35 ± 5 mL·kg-1; P = 0.03) compared with non-CMS. There were no differences in ePASP between groups (non-CMS 32 ± 9 mmHg vs. CMS 31 ± 8 mmHg; P = 0.6). A negative correlation was found between plasma renin activity and glomerular filtration rate in both groups (group r = -0.66; P < 0.01; non-CMS r = -0.60; P = 0.022; CMS r = -0.63; P = 0.049). A smaller plasma volume in Andeans with CMS may indicate an additional CMS maladaptation to high altitude, causing potentially greater polycythemia and clinical symptoms.