Mr. Smith, aged 60 years, had hypertension for almost 20 years. Recently, his legs and feet are swollen, his weight has increased, headaches are frequent, he feels tired, and has lost his appetite. His blood pressure is 160/105, and he has elevated blood creatinine and urea levels. His urine is diluted. His hemoglobin is low, serum bicarbonate is low, and serum sodium is low. Has he developed nephrosclerosis? Why is he developing edema and gaining weight? Why is he voiding dilute urine? Why does he have anemia and metabolic acidosis? What should be the treatment?