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 can cause general weakness in a 77-year-old patient with eGFR 37 and rising CRP 82.8 and mild hypokalemia and mild hyperglycemia and mild normocytic anemia, as it may lead to electrolyte depletion, particularly hypokalemia, which can cause weakness, among other symptoms 1.
From the Research
Yes, furosemide can cause general weakness in a 77-year-old patient with the described clinical profile. Furosemide is a loop diuretic that increases urinary excretion of sodium, chloride, and water, which can lead to electrolyte imbalances, particularly hypokalemia, as seen in a case report of a patient with severe hypokalemia secondary to furosemide 2. In this patient with existing mild hypokalemia, furosemide may be exacerbating potassium loss, contributing to muscle weakness. Additionally, the patient's reduced kidney function (eGFR 37) can lead to altered drug metabolism and increased risk of adverse effects, as noted in a study on the pharmacokinetics of furosemide 3. The rising CRP (82.8) suggests inflammation or infection, which combined with medication side effects, can intensify feelings of weakness. The patient's mild hyperglycemia may also contribute to fatigue, as can the normocytic anemia. Management should include potassium supplementation, possibly reducing the furosemide dose, monitoring electrolytes more frequently, and investigating the cause of the elevated CRP and anemia, as suggested by the most recent study on furosemide-induced hypokalemia 2. Ensuring adequate hydration while maintaining the therapeutic benefits of the diuretic is important. The combination of age, reduced kidney function, and multiple metabolic abnormalities makes this patient particularly vulnerable to medication-induced weakness. Some key points to consider in managing this patient include:
- Monitoring electrolyte levels closely, especially potassium, to prevent further imbalances 4
- Adjusting the furosemide dose to minimize adverse effects while maintaining its therapeutic benefits 5
- Investigating and addressing the underlying causes of the elevated CRP and anemia to reduce overall morbidity and mortality.