CaREFREE Study (Calorie Restriction, Environment and Fitness: Reproductive Effects Evaluation Study)

Functional hypothalamic amenorrhea (HA) is a reversible form of hypogonadotropic hypogonadism (HH) that can be triggered by stressors such as exercise, nutritional deficits, and psychological stress. Dysfunction of the hypothalamic component of the reproductive axis plays a key role in functional HA and is manifest by an altered pattern of luteinizing hormone (LH) pulses detectable in peripheral blood. There is ample evidence supporting the use of LH as a surrogate marker of hypothalamic gonadotropin-releasing hormone (GnRH) secretion from the hypothalamus. There is also significant evidence that women vary in their susceptibility to such stress-induced amenorrhea, pointing to a role for both environmental and genetic factors in the etiology of functional HA. However, the variation in changes in GnRH pulse frequency in response to stressors in healthy women has not been defined. Data from previous work in our lab has suggested that rare variants in genes associated with other forms of HH may also contribute to the variability seen in susceptibility to functional HA. The long-term goal of our research is to examine the interaction of environment and genes in HA. In this pilot study we propose to examine the inter-individual variability in pulsatile LH secretion in response to standardized neutral and deficient energy availability (NEA and DEA, respectively) in normal women. We will then relate this primary end-point to proposed predictive factors including past reproductive and family history and markers of current metabolic status and their response to energy availability. Our initial analyses will help to determine simplified biomarkers that can be translated to larger studies examining the potential combined effect of energy availability and genotype.

The proposed pilot study is a single-site, 2-period study in healthy female volunteers. The study will enroll approximately 300 participants with a target for study completion of 36 subjects. Eligible participants will be females \>= 18 years of age. Eligible participants will have had menarche at or before 14 years of age and no earlier than age 11. Eligible participants will have a gynecological age (years after menarche) of 14 years or less. The upper age limit will vary based on each subject s age of menarche and fall between 25 and 28 among participants. Eligible participants will confirm at the pre-screening call having normal menstrual cycles (self-reported) for at least the previous 2 months and ovulation will be confirmed during the menstrual cycle before the start of intervention.

The primary outcome will be changes in daytime LH pulse frequency, when comparing NEA vs DEA. Secondary measures will evaluate past reproductive history, family history, and current metabolic status using medical history interviews, lifestyle questionnaires and maximum oxygen uptake (as a measure of fitness). Resting energy expenditure, body composition as well as metabolic and stress hormones will be measured at baseline and in association with the interventions.