What are the management options for a 65-year-old female with elevated Blood Urea Nitrogen (BUN) and chloride levels, and a slightly low Glomerular Filtration Rate (GFR)?

Management of Elevated BUN, Chloride, and Slightly Low GFR in a 65-Year-Old Healthy Female

The most appropriate management for a 65-year-old healthy female with elevated BUN, chloride, and slightly low GFR includes assessment of hydration status, evaluation of medication use, and consideration of dietary modifications while monitoring renal function. 1

Initial Assessment and Diagnosis

• Evaluate hydration status as dehydration is a common cause of elevated BUN and chloride in elderly patients 1, 2
• Assess for possible prerenal causes of elevated BUN, which may indicate decreased renal perfusion rather than intrinsic kidney disease 3, 4
• Consider BUN as an independent marker of kidney function, as it may reflect increased proximal tubular reabsorption in addition to decreased GFR 5
• Measure serum creatinine and calculate eGFR using the 2009 CKD-EPI equation for more accurate assessment of kidney function 1
• Monitor electrolytes including potassium and sodium levels, as they may be affected by mild renal dysfunction 1

Management Approach

Hydration and Diet Modifications

• Ensure adequate hydration with appropriate fluid intake to improve prerenal azotemia 2
• Restrict dietary sodium to <2.0 g/d (<90 mmol/d) if hypertension or fluid retention is present 1
• Consider dietary protein intake of approximately 0.8 g/kg body weight per day (recommended daily allowance) for non-dialysis dependent patients with mild kidney dysfunction 1
• Avoid excessive protein intake which can further elevate BUN levels 1, 4

Medication Review and Adjustments

• Review and potentially adjust medications that may affect renal function or electrolyte balance 1
• Consider discontinuation or dose reduction of nephrotoxic drugs such as NSAIDs or COX-2 inhibitors 1
• If hypertension is present, consider ACE inhibitors or ARBs as first-line therapy, which can help preserve kidney function 1
• Monitor serum creatinine and potassium levels when initiating ACE inhibitors or ARBs, as these medications can cause modest increases in creatinine (up to 30%) 1

Monitoring and Follow-up

• Schedule regular monitoring of renal function with serum creatinine, BUN, and electrolytes 1
• Track GFR trends over time rather than focusing on a single slightly low value 1
• Monitor for signs of worsening kidney function, including increasing BUN and creatinine levels 4
• Consider referral to a nephrologist if GFR continues to decline or falls below 30 mL/min/1.73 m² 1

Special Considerations

• Elevated BUN has been shown to be an independent risk factor for adverse outcomes, even with only mildly reduced GFR 3, 5
• Higher BUN levels are associated with increased risk of coronary heart disease in middle-aged and elderly populations 3
• Mild renal dysfunction in elderly patients is common and may not necessarily indicate progressive kidney disease 1
• Consider the impact of age-related decline in GFR when interpreting laboratory values in a 65-year-old patient 1

Common Pitfalls to Avoid

• Do not rely solely on serum creatinine to assess renal function, as it may be low due to decreased muscle mass in elderly females 1
• Avoid excessive fluid restriction which can worsen prerenal azotemia and further elevate BUN 2
• Do not dismiss slightly low GFR as clinically insignificant, as it may indicate early kidney disease requiring intervention 4
• Avoid aggressive diuretic therapy without careful monitoring, as it can worsen azotemia and electrolyte imbalances 2