Quick facts
| Fact | Spironolactone |
|---|---|
| Drug class[1][2] | Potassium-sparing diuretic; aldosterone antagonist (it blocks aldosterone in the kidney) |
| Used for[1] | Heart failure with reduced ejection fraction (New York Heart Association, NYHA, class III to IV); add-on treatment for high blood pressure; edema from cirrhosis or nephrotic syndrome; primary hyperaldosteronism (too much aldosterone) |
| Contraindicated with[1] | Hyperkalemia, Addison's disease, or taking eplerenone |
| Check[1] | Potassium within 1 week of starting or a dose change, then regularly; fluid status and kidney function; electrolytes, uric acid, and glucose |
| Raise potassium further[1] | Potassium supplements, salt substitutes, ACE inhibitors, angiotensin receptor blockers (ARBs), nonsteroidal anti-inflammatory drugs (NSAIDs), heparin, and trimethoprim |
| Other effects[1] | Breast enlargement (gynecomastia), usually reversible; low sodium, magnesium, or calcium; high glucose and uric acid |
Before giving spironolactone: potassium and kidney function
- Check the potassium. Hyperkalemia is more likely when kidney function is poor or the patient also takes potassium supplements, potassium salt substitutes, ACE inhibitors, or ARBs.[1]
- Potassium may need checking more often in a patient with kidney impairment or taking other drugs that raise potassium.[1]
- If the potassium is high, the dose is lowered or the drug is stopped and the hyperkalemia is treated, so report a high result.[1]
- In heart failure, potassium supplements are generally stopped when spironolactone starts.[1]
- Too much diuresis can cause dehydration, low blood pressure, and worse kidney function, especially in a patient low on salt or taking ACE inhibitors or ARBs, so watch fluid status and kidney function.[1]
- Report urine output below 30 mL/hour.[2]
Other warnings: electrolytes, breast enlargement, liver disease, lithium, and pregnancy
- It can also lower sodium, magnesium, and calcium, cause low chloride with a raised blood pH (hypochloremic alkalosis), and raise blood glucose and uric acid, so electrolytes, uric acid, and glucose are checked from time to time.[1]
- Breast enlargement (gynecomastia) developed in about 9% of men taking it for heart failure in the RALES trial. The risk rises with the dose, it can appear anywhere from 1 to 2 months to more than a year after starting, and it is usually reversible.[1]
- In cirrhosis with ascites, sudden fluid and electrolyte shifts can worsen hepatic encephalopathy, so it is started in the hospital.[1]
- It slows how fast the kidneys clear lithium, which raises the risk of lithium toxicity, so lithium levels are checked periodically.[1]
- It falsely raises the result of some digoxin blood tests, so a patient who takes both needs a test method it doesn't affect.[1]
- In pregnancy it is avoided, or the patient is told about the possible risk to a male fetus, because it blocks the effects of male sex hormones.[1]
Teach the patient to avoid salt substitutes and high-potassium foods
- Avoid potassium supplements, salt substitutes, and foods high in potassium.[1][2]
- Take it in the morning to avoid getting up at night to urinate, at the same time each day, and report big weight changes.[2]
- It can be taken with or without food, but the same way each time.[1]
- Change positions slowly, because diuretics can make blood pressure drop on standing.[2]
Spironolactone appears in MagstoneRN's Bowtie, Matrix, and select-all-that-apply pharmacology practice, and the app's clinical tools include a drug reference for it.
Browse clinical toolsHow it shows up on nursing exams
- In the distal tubule, aldosterone makes the kidneys hold on to sodium and let potassium go. Spironolactone blocks aldosterone there, so sodium and water leave and potassium stays.[1][2]
- Because it keeps potassium, an ACE inhibitor, an ARB, or a potassium supplement given with it makes hyperkalemia more likely.[1]
- For the same reason, it can help with edema when another diuretic has caused hypokalemia.[1]
Practice question
A patient with heart failure who takes lisinopril started spironolactone 5 days ago. The laboratory reference range for potassium is 3.5 to 5.1 mEq/L. Which finding should the nurse report to the health care provider first?
- A. Blood pressure 118/72 mm Hg
- B. Urine output 45 mL/hour
- C. Serum potassium 5.8 mEq/L
- D. Weight down 1 pound since yesterday
Show the answer and why
Correct answer: C. Serum potassium 5.8 mEq/L
- A. Incorrect. Lowering blood pressure is one of spironolactone's intended effects, and this reading is not low enough to report first.
- B. Incorrect. Urine output is reported when it falls below 30 mL/hour. 45 mL/hour is above that.
- C. Correct. 5.8 mEq/L is above the range. Spironolactone can cause hyperkalemia, and an ACE inhibitor such as lisinopril makes it more likely. A high potassium means a lower dose or stopping the drug, so this is reported first.
- D. Incorrect. A small weight loss fits the intended diuresis. It does not outrank a high potassium.
Sources for this question: [1][2][3]
Memory hook: Spironolactone spares potassium: no salt substitutes, no extra potassium, and keep an eye on the potassium level.