The Effects of Estradiol and Progesterone on Arginine Vasopressin Regulation and Serum Sodium Concentration
Information source: Yale University
Information obtained from ClinicalTrials.gov on October 19, 2009
Link to the current ClinicalTrials.gov record.
Condition(s) targeted: Exercise Induced Hyponatremia
Intervention: Gatorade Endurance Formula (Dietary Supplement); ganirelix acetate (Other)
Phase: N/A
Status: Recruiting
Sponsored by: Yale University Official(s) and/or principal investigator(s):
Nina Stachenfeld, PhD, Principal Investigator, Affiliation: John B. Pierce Laboratory
Overall contact:
Nina Stachenfeld, PhD, Phone: 203-562-9901, Ext: 219, Email: nstach@jbpierce.porg
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).
Clinical Details
Official title: The Effects of Estradiol and Progesterone on Arginine Vasopressin Regulation and Serum Sodium Concentration
Study design: Basic Science, Randomized, Open Label, Active Control, Parallel Assignment, Efficacy Study
Primary outcome: osmotic regulation of AVP
Secondary outcome: temperature responses
Eligibility
Minimum age: 18 Years.
Maximum age: 35 Years.
Gender(s): Female.
Criteria:
Inclusion Criteria:
- healthy volunteers (18-35 yrs) with and without previous exercise induced
hyponatremia
Exclusion Criteria:
- conditions that would preclude safe exercise or safe use of hormones
Locations and Contacts
Nina Stachenfeld, PhD, Phone: 203-562-9901, Ext: 219, Email: nstach@jbpierce.porg
John B. Pierce Laboratory, New Haven, Connecticut 06519, United States; Recruiting
Nina Stachenfeld, PhD, Principal Investigator
Additional Information
Starting date: January 2006
Ending date: December 2009
Last updated: February 13, 2009
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