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The Effects of Estradiol and Progesterone on Arginine Vasopressin Regulation and Serum Sodium Concentration

NCT00589134 · Status: COMPLETED · Phase: NA · Type: INTERVENTIONAL · Enrollment: 26

Last updated 2020-03-30

No results posted yet for this study

Summary

Women are at greater risk for exercise-induced hyponatremia (low blood sodium concentration) and this risk has been attributed to their lower body weight and size, excess water ingestion and longer racing times relative to men. While these factors contribute to the greater incidence of hyponatremia in women, it is likely that their greater levels of estradiol in plasma and/or tissue also play a role in increasing the risk of hyponatremia in women. More importantly, estradiol may also leave women more susceptible to the extreme consequences of hyponatremia (i.e. brain damage, death). Hyponatremia is generally attributed to inappropriately elevated levels of the hormone arginine vasopressin (AVP). AVP is the most important hormone controlling water retention in the kidney. Earlier studies in our laboratory have demonstrated that estradiol lowers the threshold for thirst sensation and AVP release during exercise. The purpose of these studies is to test the hypotheses that in women with a history of hyponatremia, estradiol lowers the thresholds for thirst and AVP release, leading to greater fluid retention, lower blood sodium concentration during endurance exercise in the heat. However, we further hypothesize that progesterone administration along with estradiol administration will attenuate the effect of estradiol on the regulation of thirst and AVP, normalize fluid retention, and serum sodium concentration during endurance exercise in the heat. In women without a history of hyponatremia, we expect that estradiol administration will lower the thresholds for thirst and AVP release, but will not increase fluid retention or reduce blood sodium concentration during endurance exercise in the heat. We hypothesize that progesterone administration along with estradiol administration will attenuate the effect of estradiol on thirst and AVP, but have no effect on fluid retention or serum sodium concentration during endurance exercise in the heat. To test these hypotheses, women will perform endurance exercise in the heat under three hormonal conditions: 1) during Gonadotropin-releasing hormone (GnRH) antagonist alone--which will suppress estradiol and progesterone; 2) during GnRH antagonist+estradiol; and 3) during GnRH antagonist+estradiol+ progesterone. During exercise, fluid will be replaced with either water or a carbohydrate-electrolyte beverage (random assignment).

Conditions

  • Exercise Induced Hyponatremia

Interventions

DIETARY_SUPPLEMENT

Gatorade Endurance Formula

carbohydrate electrolyte beverage

OTHER

ganirelix acetate

GnRH antagonist, subcutaneous injection, 0.25 mg/day for 21 days.

Sponsors & Collaborators

  • Yale University

    lead OTHER

Principal Investigators

  • Nina Stachenfeld, PhD · John B. Pierce Laboratory

Study Design

Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Model
PARALLEL

Eligibility

Min Age
18 Years
Max Age
35 Years
Sex
FEMALE
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2006-01-31
Primary Completion
2009-12-31
Completion
2009-12-31

Countries

  • United States

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT00589134 on ClinicalTrials.gov