POMC and Adrenal insufficiency: The patient's clinical presentation (pallor, worsening fatigue, anorexia, nausea, vomiting, weight loss) combined with laboratory findings (severe hyponatremia, elevated urea, and creatinine due to dehydration and hemoconcentration, hypocortisolism with high ACTH levels) led to the diagnosis of adrenal insufficiency (Addison’s disease).