The objective of this protocol is to use a case-control paradigm to compare the response to an intravenous administration of kisspeptin in individuals with and without post-covid-19 syndrome. The study subjects will receive a single bolus of kisspeptin.

This study will utilize the technique of frequent blood sampling (q10 minutes) to provide detailed neuroendocrine characterization of endogenous LH secretion before and after kisspeptin administration. This frequency of blood sampling is required to define the features of LH pulses.

Delivery of Interventions:

• 1-2 hours of q10 minute blood sampling
• Administration of a single kisspeptin bolus in a dosing range of 0.313 - 13.19 μg/kg

Inclusion Criteria

• Female (ages 18-45 years) or Male (ages 18-60 years)
• Normal blood pressure (systolic BP < 140 mm Hg, diastolic < 90 mm Hg)
• Hemoglobin no less than 0.5 g/dL below the lower limit of the sex specific reference range
• No current or recent use of a medication (including hormonal replacement) that, in the opinion of a study investigator, can modulate the reproductive axis or willing to complete an appropriate washout for that particular medication and its method of administration
• For women, negative serum hCG pregnancy test
• For cases, diagnosis of post-covid-19 syndrome
• For controls, history of prior covid infection but no diagnosis of post-covid-19 syndrome

Exclusion Criteria

• Any condition (medical, mental, or behavioral) that, in the opinion of a study investigator, would likely interfere with participation in/completion of the protocol
• Excessive alcohol consumption (>10 drinks/week)
• Active use of illicit drugs
• For women,
• Pregnant
• Trying to become pregnant during protocol participation
• Breast feeding
• History of any of the following: bilateral oophorectomy (ovaries were removed), breast cancer, thromboembolic disease, coronary artery disease, stroke, thrombophilic disorders, or undiagnosed abnormal genital bleeding