A 43 year old man presents to his physician with persistent dizziness when standing quickly. He also has been exhibiting chronic fatigue,  muscle weakness, and an unusual craving for salty foods. The physician notices that the patient has a constant “bronze, tan,” and blood obtained during the visit demonstrated normal cholesterol levels but also hypoglycemia, hyperkalemia, and hyponatremia.

What is the most likely underlying cause for these problems ?