Problem: Jameson, a 71-year-old male, presents for follow-up after presenting with refractory hypertension one month ago. His medication regimen includes enalapril and hydrochlorothiazide but has not been successful, and his blood pressure remains consistently elevated above 140/100 mmHg. He agrees to start treatment with a potassium-sparing diuretic, amiloride. Which of the following serum laboratory changes is expected in this patient?
- Increased calcium
- Decreased sodium
- Increased magnesium
- Decreased chloride