The diuretic definition is anything that promotes the body to lose water by increasing the excretion of urine and fluids. Diuretics cause the kidneys to excrete more water and sodium. They are used to eliminate excess fluid and decrease swelling.
There are three main types of diuretics: thiazide, loop, and potassium-sparing. They work differently to achieve the same effect. Thiazide diuretics are most commonly used to treat high blood pressure, while the more powerful loop diuretics are often used in kidney and heart failure. Potassium-sparing diuretics are weaker and are mostly used in combination with thiazide or loop diuretics to prevent the loss of potassium that occurs with diuretic use.
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In the past, standard medical therapy for heart failure consisted of three main classes of drugs:
- Digoxin to increase the heart’s pumping ability.
- A diuretic to eliminate excess fluid.
- An ACE inhibitor to increase blood flow.
With the advent of beta-blockers, and compelling evidence of their effectiveness, recommendations changed. In general, patients are now treated with an ACE inhibitor or angiotensin receptor blocker (ARB), plus a diuretic and a beta-blocker, to which an aldosterone antagonist or digoxin can be added.
Heart failure specialists prescribe diuretics for approximately 90 percent of patients, and strive to use the lowest effective dose. You may be allowed to adjust your own diuretics based on your symptoms, following specific instructions from your doctor. You will monitor your weight daily, and if you gain more than three pounds above your normal, baseline weight, you may increase the diuretic dose as instructed.
Some people with mild or moderate heart failure who take an ACE inhibitor and beta-blocker do not need a daily diuretic. As heart failure becomes more severe, diuretic requirements increase. Not complying with your sodium and fluid restrictions will also lead to greater fluid retention and a heavier reliance on diuretics.
Diuretic Dosing and Side Effects
The diuretic your doctor prescribes will depend on your individual situation. The vast majority of heart failure patients are started on a loop diuretic such as furosemide (Lasix), bumetanide (Bumex), or torsemide (Demadex). Those who need a stronger diuretic effect may require a combination of loop and thiazide diuretics. Spironolactone (Aldactone) is a potassium-sparing diuretic and neurohormonal modulator that improves survival in patients with severe heart failure when added to therapy with an ACE inhibitor, beta-blocker, digoxin, and diuretics.
For patients with acute decompensated heart failure who no longer benefit from traditional diuretics, intravenous treatment with a synthetic natriuretic peptide such as ularitide may help.
Diuretic doses are based on the severity of heart failure, as well as on diet, salt and fluid intake, activity level, and kidney function. Doses are adjusted as needed to relieve swelling and congestion. High doses can cause fluid and electrolyte imbalances from loss of sodium and water. Loss of too much sodium can cause hypotension, dehydration, and worsening kidney function. Overly aggressive use of diuretics can also cause imbalances in other minerals and electrolytes in the body, including potassium, magnesium, calcium, and chloride. Elderly or debilitated patients are more susceptible to these adverse effects than younger patients. Sometimes, a high dose of diuretics will be given intravenously or in bolus form (a large amount given at one time).
If you take diuretics, it is important to keep your blood potassium level normal to prevent an abnormal heart rhythm from occurring. Potassium-sparing diuretics raise blood potassium levels. Thiazide and loop diuretics lower blood potassium levels. Either way, severe imbalances produce the same symptoms: weakness, numbness, confusion, and heaviness in the legs. If you take a thiazide or loop diuretic, and are not on a potassium-sparing diuretic it is important to eat potassium-rich foods, such as baked potatoes, dried fruit, white beans, cantaloupe, and spinach. You may also need a potassium supplement. However, never take a potassium supplement or a salt substitute containing potassium unless instructed by your doctor, no matter which type of diuretic you are taking.
A few people who use diuretics find they sunburn more easily, and some may get a rash. A common effect of diuretic use is dry mouth—if this happens to you, use sugar-free hard candy to stimulate the flow of saliva. People who take diuretics are more susceptible to attacks of gout, a type of arthritis that causes painful joint inflammation. Diuretics may also cause nausea, confusion, drowsiness, weakness (due to low blood pressure), and muscle or leg cramps. If you experience any of these side effects, tell your doctor.