A physician orders spironolactone (Aldactone), 50 mg by mouth four times daily, for a client with fluid retention caused by cirrhosis. Which finding indicates that the drug is producing a therapeutic effect?

• A. Serum potassium level of 3.5 mEq/L
• B. Loss of 2.2 lb (1 kg) in 24 hours
• C. Blood pH of 7.25
• D. Serum sodium level of 135 mEq/L

Answer: (B)

Spironolactone helps remove excess fluid in cirrhosis by blocking aldosterone in the distal nephron, which promotes sodium and water excretion while sparing potassium. The therapeutic goal in fluid overload from cirrhosis is to reduce total body fluid, so an actual loss of about 1 kg in 24 hours signals effective diuresis and improved edema/ascites. The weight change directly reflects the drug’s intended effect on fluid status. Monitoring for hyperkalemia is important with this medication, since potassium can rise, but a simple normal or low potassium level alone does not demonstrate that fluid removal is occurring. Abnormal acid-base status or normal sodium level are not reliable indicators of spironolactone’s therapeutic effect in this context.