The purpose of this research study is to validate (check the accuracy of) laboratory assays, intravenous catheter insertion, and equipment or devices and their reproducibility, which is necessary to perform high quality research on chronic diseases, nutrition, and metabolism (the process by which a substance is handled in the body) at the University of Missouri. As technology changes and uses new testing methods, it is necessary to compare results from old tests, equipment and devices and new tests, equipment, or devices and the reproducibility of these measurements to make sure the results are accurate. Reproducibility means performing the same test more than once to see if the same results can be achieved each time. This study will look at the validation and reproducibility of tests and laboratory assays in participants who are healthy or affected by relevant endocrine, cardiometabolic, and musculoskeletal disorders.