Kisspeptin to Quantify GnRH Neuronal Function in Health and Disease

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