A patient was admitted with abdominal pain, diarrhea, pigmented palmar creases and buccal mucosa. What is the most probable diagnosis?

The key is A. Addison’s disease. [Addison's disease, also known as primary adrenal insufficiency and

hypocortisolism, is a long-term endocrine disorder in which the adrenal glands do not produce enough

steroid hormones. Symptoms generally come on slowly and may include abdominal pain, weakness, and

weight loss, diarrhea, pigmented palmar creases and buccal mucosa].