This case report presents the diagnosis, clinical management, and treatment outcomes of a 29-year-old female GR patient diagnosed with Addison's Disease, a rare endocrine disorder characterized by primary adrenal insufficiency. Over two years, the patient exhibited significant clinical manifestations, including skin hyperpigmentation, severe weight loss, asthenia, nausea, and generalized weakness, which led to her eventual diagnosis. The case emphasizes the challenges of diagnosing Addison’s Disease due to its nonspecific symptoms and the critical importance of comprehensive clinical and biochemical evaluations to establish a timely and accurate diagnosis. Treatment involved hormone replacement therapy, including glucocorticoids and mineralocorticoids, resulting in a notable improvement in the patient's condition. This report emphaizes the need for early detection and management of Addison’s Disease to prevent acute adrenal crises and improve patient outcomes.