From the Guidelines
Furosemide (Lasix) can cause hyponatremia, particularly in patients with heart failure, cirrhosis, or kidney disease who have impaired free water excretion. According to the most recent guidelines on the management of ascites in cirrhosis 1, patients on diuretics, including furosemide, should be monitored for adverse events, including hyponatremia. The mechanism of hyponatremia involves furosemide blocking sodium reabsorption in the loop of Henle, disrupting the kidney's ability to dilute urine appropriately.
Risk Factors for Hyponatremia
The risk of hyponatremia increases with higher doses of furosemide and is more common in:
- Elderly patients
- Patients taking other medications that affect sodium levels
- Patients with poor dietary sodium intake
- Patients with heart failure, cirrhosis, or kidney disease
Monitoring and Management
Patients on furosemide should be monitored for symptoms of hyponatremia, including:
- Confusion
- Headache
- Nausea
- Muscle cramps
- Seizures or coma (in severe cases) Regular electrolyte monitoring is recommended, especially when initiating therapy or changing dosages. If hyponatremia occurs, diuretics can be carefully reduced or discontinued, and fluid restriction can be considered 1.
Key Recommendations
- In patients with the first presentation of moderate ascites, spironolactone monotherapy or combination therapy with spironolactone and furosemide can be used 1.
- All patients initiating diuretics should be monitored for adverse events, including hyponatremia 1.
- Hypovolaemic hyponatraemia during diuretic therapy should be managed by discontinuation of diuretics and expansion of plasma volume with normal saline 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): dryness of mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, arrhythmia, or gastrointestinal disturbances such as nausea and vomiting.
Yes, Furosemide (Lasix) can cause hyponatremia as it is listed as one of the signs or symptoms of fluid or electrolyte imbalance that patients should be observed for during therapy 2.
From the Research
Furosemide and Hyponatremia
- Furosemide, a loop diuretic, can be associated with hyponatremia, particularly at high doses 3, 4.
- A study found that furosemide doses of 250 to 500 mg were independently associated with hyponatremia in patients with heart failure 3.
- However, another study suggested that ongoing use of furosemide may have a protective effect against hospitalization due to hyponatremia, with an adjusted odds ratio of 0.52 4.
- The pathophysiology of diuretic resistance, which can occur with furosemide, includes mechanisms that can lead to hyponatremia, such as tubular tolerance and enhanced reabsorption in the proximal tubule 5.
Comparison with Other Diuretics
- A study compared the efficacy of furosemide with or without sodium chloride supplementation, combined with fluid restriction, in the treatment of hyponatremia in patients with syndrome of inappropriate antidiuresis (SIAD) 6.
- The study found that furosemide with or without sodium chloride supplementation did not show benefits in correction of serum sodium compared with treatment with fluid restriction alone 6.
- Another study compared a tolvaptan-based diuretic regimen with a furosemide-based regimen in patients hospitalized for heart failure with hyponatremia, and found that oral tolvaptan was associated with similar, but not superior, diuresis compared with intravenous furosemide 7.
Clinical Implications
- High doses of furosemide, particularly in combination with other diuretics, may increase the risk of hyponatremia in patients with heart failure 3, 4.
- The use of furosemide should be carefully monitored, and patients should be educated on the signs and symptoms of hyponatremia 3, 4.
- Alternative diuretic regimens, such as tolvaptan, may be considered in patients with heart failure and hyponatremia who do not respond to furosemide-based therapy 7.