Module I: Endocrinology, a core course in the Fellowship, is critical in helping to develop the necessary skills to treat complex patients. This module focuses on the hormonal changes that manifest in both men and women through the aging process, in addition to a review of patient case studies and interactive discussion with leading hormone experts. Sessions will review basic function of sex steroids in the body, tools to test and optimize hormone replacement therapy in men and women. The module will also further expand on endocrine disruptors and ways to detoxify and assist in healthy metabolism of hormones. We will also provide a model of whole person care in the context of hormone replacement therapy. Resilience is a key factor in wellness and longevity and this module will also provide a review of HPA function; ways to improve resilience and stress management.