A 65-year-old woman with heart failure on lisinopril and furosemide is started on spironolactone. Three weeks later, she presents with weakness and palpitations. Vital signs: BP 98/62 mmHg, HR 108 bpm, RR 16, temp 37°C. Labs reveal K+ 6.5 mEq/L, creatinine 1.8 mg/dL (baseline 1.0), normal magnesium. ECG shows peaked T waves. Which mechanism of spironolactone most directly explains this complication?
- A)Aldosterone antagonism reducing potassium excretion and sodium reabsorption in the distal tubuleGABARITO
- B)Spironolactone directly activates potassium channels in the collecting duct
- C)Inhibition of proximal tubule potassium reabsorption
- D)Increased renal blood flow promoting potassium filtration
- E)Competitive inhibition of the Na-K-ATPase pump
Explicação
Spironolactone is an aldosterone antagonist that blocks mineralocorticoid receptors in the distal tubule and collecting duct. By antagonizing aldosterone, spironolactone reduces sodium reabsorption and potassium excretion, causing potassium retention. When com... Ver explicação completa e trilha adaptativa →