What is the treatment for impaired renal function?

Management of Chronic Kidney Disease Stage 3b (GFR 47 mL/min)

For a patient with BUN 27, creatinine 1.75, and GFR 47, treatment should focus on slowing CKD progression, managing complications, and reducing cardiovascular risk through medication adjustments, blood pressure control, and lifestyle modifications.

Classification and Risk Assessment

• The laboratory values (BUN 27, creatinine 1.75, GFR 47) indicate Stage 3b Chronic Kidney Disease with moderate reduction in kidney function 1
• This stage is associated with increased risk for progression to end-stage renal disease and adverse cardiovascular outcomes 1

First-Line Pharmacological Management

• ACE inhibitors or ARBs should be initiated and titrated to maximally tolerated doses to reduce proteinuria, slow CKD progression, and reduce cardiovascular events 1
• Monitor serum creatinine after starting ACE inhibitors/ARBs; an initial increase up to 30% is acceptable and usually returns to baseline 1
• Discontinue ACE inhibitors/ARBs if kidney function continues to worsen or if refractory hyperkalemia develops 1
• For patients with diabetes or non-diabetics with proteinuria >200 mg/g creatinine, ACE inhibitors or ARBs should be first-line therapy 2

Blood Pressure Management

• Target blood pressure should be <130/80 mmHg for all CKD patients 2
• More recent guidelines suggest a target systolic blood pressure of <120 mmHg using standardized office blood pressure measurement 1
• Combination therapy is often necessary to achieve target blood pressure 1, 3
• Diuretics should be added after initial dosing with an ACE inhibitor or ARB 2

Medication Adjustments and Precautions

• Dose adjustment is required for many medications cleared by the kidneys 1, 4
• Avoid nephrotoxic medications, particularly NSAIDs, which can worsen kidney function 1, 5
• For patients with GFR <30 mL/min, thiazide diuretics become ineffective and loop diuretics are preferred 6
• Medications requiring specific dose adjustments in renal impairment:
  • Ramipril: Initial dose 1.25 mg daily if CrCl <30 mL/min, not exceeding 5 mg/day 1
  • Atenolol: Half dose (50 mg/day) for CrCl between 15-35 mL/min 1

Management of Metabolic Complications

• Consider statin therapy for cardiovascular risk reduction 1, 5
• Restrict dietary sodium to <2.0 g/day (<90 mmol/day) 1
• For edema management, use loop diuretics as first-line therapy, preferably with twice daily dosing 1
• Consider switching to longer-acting loop diuretics (bumetanide, torsemide) if furosemide is ineffective 1

Lifestyle Modifications

• Dietary sodium restriction to no more than 2 grams daily is important 2
• Recommend moderate alcohol intake, regular exercise, weight loss for BMI >25 kg/m², and reduced saturated fat intake 2
• These non-pharmacological interventions are useful in reducing BP in CKD but are rarely sufficient alone 3

Monitoring and Follow-up

• Regular monitoring of kidney function (eGFR and albuminuria) is essential 5
• Monitor for complications such as anemia, metabolic acidosis, and mineral and bone disorder 5
• Consider referral to a nephrologist if GFR declines rapidly or falls below 30 mL/min/1.73 m² 1, 5

Common Pitfalls to Avoid

• Failing to adjust medication dosages based on reduced kidney function can lead to drug toxicity 4
• Continuing nephrotoxic medications (like NSAIDs) can accelerate kidney function decline 1, 5
• Inadequate blood pressure control accelerates CKD progression 2, 3
• Overlooking the need for comprehensive cardiovascular risk reduction in CKD patients 7

By following these evidence-based recommendations, progression of kidney disease can be slowed, complications minimized, and quality of life preserved for patients with Stage 3b CKD.