• Age 18 years and older,

• Confirmed diagnosis of HH with

‣ Low testosterone or estradiol,

⁃ Low or low-normal gonadotropin levels,

⁃ Thyroid stimulating hormone (TSH) and prolactin within the reference range,

⁃ Absence of abnormal pituitary or hypothalamic findings on Magnetic resonance imaging (MRI),

• All other medical conditions stable and well controlled,

• No prescription medications known to affect reproductive endocrine function for at least 2 months or for 5 half-lives of the drug (whichever is shorter) except for medications used to treat the subject's reproductive condition,

• No history of a medication reaction requiring emergency medical care,

• No illicit drug use,

• No excessive alcohol consumption (\<10 drinks/week),

• Normal blood pressure (BP), (systolic BP \< 140 mm Hg, diastolic \< 90 mm Hg),

• White blood cell, platelet counts, and TSH between 90% of the lower limit and 110% of the upper limit of the reference range,

• Prolactin below 110% of the upper limit of the reference range,

• Hemoglobin

‣ Women: no less than 0.5 gm/dL below the lower limit of the reference range for normal women,

⁃ Men: on adequate testosterone replacement therapy: normal male reference range,

• Blood urea nitrogen (BUN), creatinine, aspartate aminotransferase (AST), alanine transaminase (ALT) not elevated,

• For women,

‣ Negative serum human chorionic gonadotropin (hCG) pregnancy test at the time of screening (additional urine pregnancy test will be conducted prior to drug administration),

⁃ Not breastfeeding and not pregnant.