(1) A 48-year-old woman presented with fatigue, weakness, nausea, and dizziness. Her blood pressure dropped when moving from sitting to standing. (2) Laboratory tests revealed low sodium, high potassium, low blood cells, and very high ACTH levels. Imaging showed atrophy of the adrenal glands. (3) She was diagnosed with Addison's disease based on her symptoms, labs, imaging and positive antibody testing. Treatment involved replacing her glucocorticoids and mineralocorticoids.