How can diuretics cause hypokalemia

Loop agents and thiazides may lead to hyponatremia, which, in the case of thiazides, may cause permanent neurologic damage. Dose-related reversible or irreversible ototoxicity may complicate treatment with loop agents. Nephrocalcinosis, nephrolithiasis, hypomagnesemia, and hyperuricemia can potentially complicate treatment with some diuretic agents.

Reported idiosyncratic reactions to diuretics include interstitial nephritis, noncardiogenic pulmonary edema, pancreatitis, and myalgias.

Conclusions: Potential side effects of a diuretic can often be anticipated from its mode of action on the kidney. ADH increases the permeability of the collecting duct to water, which leads to increased water reabsorption, a more concentrated urine and reduced urine outflow antidiuresis.

Diuretic drugs increase urine output by the kidney i. This is accomplished by altering how the kidney handles sodium.

If the kidney excretes more sodium, then water excretion will also increase. Most diuretics produce diuresis by inhibiting the reabsorption of sodium at different segments of the renal tubular system. Sometimes a combination of two diuretics is given because this can be significantly more effective than either compound alone synergistic effect. The reason for this is that one nephron segment can compensate for altered sodium reabsorption at another nephron segment; therefore, blocking multiple nephron sites significantly enhances efficacy.

Loop diuretics inhibit the sodium-potassium-chloride cotransporter in the thick ascending limb see above figure. This altered handling of sodium and water leads to both diuresis increased water loss and natriuresis increased sodium loss. By acting on the thick ascending limb, which handles a significant fraction of sodium reabsorption, loop diuretics are very powerful diuretics.

These drugs also induce renal synthesis of prostaglandins, which contributes to their renal action including the increase in renal blood flow and redistribution of renal cortical blood flow. Thiazide diuretics , which are the most commonly used diuretic, inhibit the sodium-chloride transporter in the distal tubule. Nevertheless, they are sufficiently powerful to satisfy many therapeutic needs requiring a diuretic. Their mechanism depends on renal prostaglandin production. Because loop and thiazide diuretics increase sodium delivery to the distal segment of the distal tubule, this increases potassium loss potentially causing hypokalemia because the increase in distal tubular sodium concentration stimulates the aldosterone-sensitive sodium pump to increase sodium reabsorption in exchange for potassium and hydrogen ion, which are lost to the urine.

The increased hydrogen ion loss can lead to metabolic alkalosis. Part of the loss of potassium and hydrogen ion by loop and thiazide diuretics results from activation of the renin-angiotensin-aldosterone system that occurs because of reduced blood volume and arterial pressure. Increased aldosterone stimulates sodium reabsorption and increases potassium and hydrogen ion excretion into the urine.

There is a third class of diuretic that is referred to as potassium-sparing diuretics. Unlike loop and thiazide diuretics, some of these drugs do not act directly on sodium transport. Some drugs in this class antagonize the actions of aldosterone aldosterone receptor antagonists at the distal segment of the distal tubule. They lower blood pressure by helping your body eliminate sodium and water through your urine. However, some diuretics can also cause you to eliminate more potassium in your urine.

This can lead to low potassium levels in your blood hypokalemia. Not all diuretics cause this problem. Medications called potassium-sparing diuretics don't lower potassium levels. Potassium pills are one solution, but some tend to taste bad, so people may neglect to take them. Eating foods rich in potassium, like bananas, may help, but often that's not enough.

Spironolactone Aldactone and triamterene Dyrenium are diuretics that "spare" potassium, leaving levels high, but they're pretty weak as diuretics. Dyazide available as a generic is an attempt to strike a balance: It's part thiazide, part potassium-sparing diuretic.

Taking a potassium-sparing diuretic may be especially important if you have heart failure. Diuretics are often used to fight or prevent swelling in people with heart failure, but taking a potassium-sparing diuretic helps people with heart failure feel better, stay out of the hospital, and live longer.

Heart failure patients taking the potassium-sparing diuretic are less likely to die or be hospitalized than those taking only regular diuretics. As a service to our readers, Harvard Health Publishing provides access to our library of archived content.

Please note the date of last review or update on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.