Sex hormone effects on body fluid and sodium regulation in women with and without exercise-associated hyponatremia. Journal of applied physiology (Bethesda, Md. : 1985) [J Appl Physiol] Journal article | | Title | Sex hormone effects on body fluid and sodium regulation in women with and without exercise-associated hyponatremia. | | Author(s) | Stachenfeld NS, Taylor HS | | Institution | The John B. Pierce Laboratory, Yale University School of Medicine, New Haven, Connecticut 06519, USA. nstach@jbpierce.org | | Source | J Appl Physiol 2009 Sep; 107(3):864-72. | | MeSH | Algorithms
Body Fluids
Electrolytes
Estradiol
Exercise
Exercise Test
Female
Gonadal Steroid Hormones
Gonadotropin-Releasing Hormone
Hormone Antagonists
Humans
Hyponatremia
Osmolar Concentration
Oxygen Consumption
Progesterone
Sodium
Sweating
Water-Electrolyte Balance
Young Adult
| | Abstract | We hypothesized that exercise-associated hyponatremia (EAH) is a function of excess sodium loss combined with high water intake in women at risk for dysnatremias during endurance exercise. We further hypothesized that estradiol and progesterone exposure increases fluid retention and sodium loss during exercise in women at risk for EAH. For 16 days we suppressed estrogens and progesterone with a gonadotropin-releasing hormone antagonist (GnRH ant) in seven women with (Hypo) and nine women without (no Hypo) a history of hyponatremia; we added 17beta-estradiol (0.2 mg/day patches) for days 4-16 (E(2)) and progesterone (200 mg/day) for days 13-16 (E(2)-P(4)). Under each hormone condition, subjects cycled in 35 degrees C at 65% peak oxygen consumption (Vo(2peak)) for 60 min, then at 55-60% Vo(2peak) for 120 min. Subjects drank 8 ml/kg of water (and replenished urine volume) every 30 min over the final 120 min of exercise. S([Na+]) fell by 4.3, 3.9, and 3.1 meq/l (P < 0.05) with drinking during GnRH ant, E(2), and E(2)-P(4) in Hypo, with little fall in no Hypo. Under all conditions, combined urine and sweat sodium loss were similar between Hypo [-85.6 (SD 36.2), -86.4 (SD 39.2), and -112.0 (SD 30.0) meq] and no Hypo [-98.0 (SD 54.8), -80.9 (SD 57.6), and -105.1 (SD 46.4) meq, for GnRH, E2, and E2-P4], as was mass balance of electrolytes (E(MB)) for Hypo [-104.8 (SD 32.8), -103.6 (SD 42.1), and -132.8 (SD 34.9) meq] compared with no Hypo [-128.8 (SD 57.2), -113.5 (SD 61.1), and -143.4 (SD 49.6) meq for GnRH, E2, and E2-P4]. Mass balance of water [V(MB), for Hypo, 0.42 (SD 0.10), 0.62 (SD 0.25), and -0.11 (SD 0.11) liter] compared with no Hypo [0.01 (SD 0.15), 0.03 (SD 17), and -0.16 (SD 0.13) liter for GnRH, E2, and E2-P4, P < 0.05] indicates water retention was the primary contributor to the lower S([Na+]) in Hypo women. | | Language | eng | | Pub Type(s) | Journal Article
Research Support, Non-U.S. Gov't
| | PubMed ID | 19556454 |
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