Effects of Aldosterone are High Yield for the USMLE

Scientists want to study the effect of that 1 mg of aldosterone will have on a healthy human volunteer. What changes can they predict in Na⁺ in grams, [Na⁺], pH, Urinary output, and K?

• Na⁺ in grams increases
• Aldosterone causes sodium (and water since water follows Na⁺) reabsorption in the principal cells of the distal convoluted tubule (DCT)
• Concentration of Na⁺ stays the same
• Since sodium is reabsorbed with water, the concentration will remain the same
• pH will increase
• Aldosterone causes H ion excretion in the intercalated cells of the DCT (via a Na/H-ATPase antiport pump)
• Urinary output decreases
• Since aldosterone causes the reabsorption of sodium and water from the DCT less remains in the urine that is forming
• Potassium in grams will decrease in concentration and grams
• Aldosterone is sodium sparring and potassium wasting (repeat this line to yourself 5 times)