From the Guidelines
The next best step in managing impaired renal function after initiating oral hydration is to closely monitor fluid status and kidney function through regular assessment of vital signs, daily weights, intake and output measurements, and laboratory tests, including serum creatinine, BUN, and electrolytes, as recommended by recent clinical guidelines 1.
Monitoring and Assessment
To effectively manage impaired renal function, it is essential to monitor the patient's fluid status and kidney function regularly. This includes:
- Checking serum creatinine, blood urea nitrogen (BUN), and electrolytes every 24-48 hours initially, with the frequency adjusted based on the clinical response 1.
- Maintaining urine output at greater than 0.5 mL/kg/hour, which is a critical indicator of adequate renal perfusion.
- Assessing vital signs and daily weights to evaluate the patient's overall fluid status and response to treatment.
Adjusting Treatment
If oral hydration proves insufficient, as evidenced by worsening laboratory values or clinical status, intravenous fluid administration may be necessary, typically with isotonic solutions like normal saline at rates determined by the degree of dehydration and ongoing losses. It is also crucial to review the patient's medication list and discontinue or dose-adjust nephrotoxic medications, including NSAIDs, certain antibiotics (aminoglycosides, vancomycin), and contrast agents, as these can exacerbate renal injury 1. Additionally, ACE inhibitors and ARBs may need temporary discontinuation as they can worsen renal function in volume-depleted states.
Goal of Management
The primary goal of managing impaired renal function is to restore adequate renal perfusion while identifying and addressing the underlying cause of the impaired renal function. This approach is critical because kidney function can deteriorate rapidly, and early intervention can prevent progression to more severe renal injury requiring dialysis 1. By closely monitoring the patient's fluid status and kidney function and adjusting treatment accordingly, healthcare providers can help prevent further renal damage and improve patient outcomes.
From the Research
Impaired Renal Function Management
The patient's laboratory results show an increase in BUN (32.9 ↑) and creatinine (1.2 ↑) levels, with a decrease in eGFR (51.5 ↓) after initiating oral hydration.
Next Best Step
- Monitor the patient's renal function closely, as the current eGFR level is below 60, indicating impaired renal function 2.
- Consider further evaluation and management of the patient's renal function, as renal dysfunction can predict increased mortality in patients with cardiovascular disease 2.
- Use the estimated glomerular filtration rate (eGFR) as a diagnostic tool for kidney function, as it can be measured and reported immediately using isotope dilution mass spectrometry traceable creatinine-based equations 3.
- Be aware of the limitations of using serum creatinine as a marker of kidney function, as it has substantial shortcomings, and consider alternative functional biomarkers of the kidney 4.
- Monitor the patient's potassium levels, as hyperkalemia can occur when renal potassium excretion is limited, and consider the use of potassium binders if necessary 5.
Medication Considerations
- When prescribing medications, consider the potential effects on renal function, such as the use of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or potassium-sparing diuretics, which can increase the risk of hyperkalemia 5.
- Losartan, an angiotensin II receptor antagonist, has been shown to preserve renal function in patients with essential hypertension, with no significant changes in GFR or RPF 6.