Can Lasix (furosemide) cause hyponatremia?

From the Guidelines

Yes, Lasix (furosemide) can cause hyponatremia, a condition characterized by a lower than normal sodium level in the blood, as evidenced by studies such as 1 and 1. Furosemide is a loop diuretic that works by increasing urine output, which can lead to excessive sodium loss. This medication inhibits sodium reabsorption in the kidneys' loop of Henle, causing increased sodium excretion. While furosemide is often used to treat conditions like heart failure, liver disease, and edema, the risk of hyponatremia is higher in certain populations, particularly elderly patients, those taking other medications that affect sodium levels, and patients with heart failure, cirrhosis, or kidney disease. Some key points to consider include:

• The risk of hyponatremia increases with higher doses and longer duration of treatment, as noted in 1.
• Symptoms of hyponatremia may include headache, confusion, nausea, muscle weakness, and in severe cases, seizures or coma.
• Patients taking Lasix should have their electrolyte levels monitored regularly, especially when starting treatment or adjusting dosage, and should be aware of symptoms that might indicate electrolyte imbalances, as suggested by 1.
• Monitoring of electrolyte levels is crucial, especially in patients with heart failure, as they are at a higher risk of developing hyponatremia, as discussed in 1.
• The use of furosemide requires careful consideration of the potential risks and benefits, and patients should be closely monitored for signs of hyponatremia, as emphasized in 1 and 1.

From the FDA Drug Label

As with any effective diuretic, electrolyte depletion may occur during Furosemide tablets therapy, especially in patients receiving higher doses and a restricted salt intake ... All patients receiving Furosemide tablets therapy should be observed for these signs or symptoms of fluid or electrolyte imbalance (hyponatremia, hypochloremic alkalosis, hypokalemia, hypomagnesemia or hypocalcemia)

Yes, Lasix (furosemide) can cause hyponatremia, as it may lead to electrolyte depletion, including sodium loss, especially in patients receiving higher doses and a restricted salt intake 2.

• Patients should be observed for signs or symptoms of fluid or electrolyte imbalance, including hyponatremia.
• Serum electrolytes, particularly potassium, should be determined frequently during the first few months of Furosemide tablets therapy and periodically thereafter to monitor for electrolyte imbalances, including hyponatremia.

From the Research

Lasix and Hyponatremia

• Lasix, also known as furosemide, is a loop diuretic used to treat fluid build-up and swelling caused by congestive heart failure, liver cirrhosis, or a kidney disorder 3.
• The provided studies primarily focus on thiazide diuretics as a cause of hyponatremia, with limited direct information on Lasix 4, 5, 6.
• However, one study suggests that furosemide (Lasix) may not be a common cause of hyponatremia, and its ongoing use might even have a protective effect against hospitalization due to hyponatremia 7.
• In contrast to thiazide diuretics, which are well-documented to cause hyponatremia, the evidence for Lasix causing hyponatremia is less clear 4, 5, 6.

Comparison with Thiazide Diuretics

• Thiazide diuretics are known to cause hyponatremia by impairing the ability to dilute urine, stimulating vasopressin release, and reducing glomerular filtration 4.
• The risk of hyponatremia with thiazide diuretics is greater in elderly women, and the use of other drugs like furosemide, carbamazepine, paroxetine, and NSAIDs can enhance this effect 5.
• In a review of 129 reported cases of diuretic-induced hyponatremia, thiazides were responsible for 94% of the cases, while furosemide was not associated with any cases 6.

Clinical Implications

• When using diuretics, including Lasix, it is essential to monitor serum electrolytes, especially in elderly patients or those taking other medications 5.
• The study on non-thiazide diuretics suggests that furosemide may be a safer option in terms of hyponatremia risk, but more research is needed to confirm this 7.
• Clinicians should be aware of the potential for hyponatremia with all diuretics and take steps to prevent and manage it 4, 5, 6.