From the FDA Drug Label
Reversible elevations of BUN may occur and are associated with dehydration, which should be avoided, particularly in patients with renal insufficiency The best approach to treating a patient with dehydration and impaired renal function, as indicated by elevated Blood Urea Nitrogen (BUN) and creatinine levels, is to avoid dehydration.
- Monitor serum electrolytes: Serum electrolytes (particularly potassium), CO2, creatinine and BUN should be determined frequently during the first few months of Furosemide tablets therapy and periodically thereafter.
- Correct abnormalities: Abnormalities should be corrected or the drug temporarily withdrawn.
- Use with caution: Furosemide tablets should be used with caution in patients with renal insufficiency, as they may worsen renal function 1.
- Avoid certain combinations: Furosemide tablets combined with angiotensin converting enzyme inhibitors or angiotensin II receptor blockers may lead to severe hypotension and deterioration in renal function, including renal failure 1.
From the Research
The best approach to treating a patient with dehydration and impaired renal function with elevated BUN and creatinine levels is careful fluid resuscitation with isotonic crystalloids like normal saline or lactated Ringer's solution, as supported by the most recent study 2. This approach is crucial in restoring renal perfusion, which improves glomerular filtration rate and helps clear accumulated waste products like urea and creatinine. Initial fluid administration should be guided by the patient's clinical status, typically starting with a bolus of 500-1000 mL over 1-2 hours, followed by maintenance fluids at 100-150 mL/hour, with frequent reassessment, as indicated by the principles of fluid and electrolyte balance 3. Key considerations in managing these patients include:
- Monitoring vital signs, urine output (targeting >0.5 mL/kg/hour), and serial BUN/creatinine measurements closely 4
- Discontinuing or avoiding nephrotoxic medications such as NSAIDs, aminoglycosides, and contrast agents 5
- Correcting electrolyte imbalances, particularly potassium, as needed 6
- Addressing underlying causes of dehydration, whether it's gastrointestinal losses, fever, or inadequate intake In severe cases, particularly with oliguria or anuria despite fluid resuscitation, nephrology consultation and possible dialysis may be necessary, highlighting the importance of a comprehensive approach to patient care 2.