Management of Impaired Renal Function

Initial Assessment and Cause Identification

The European Society of Cardiology recommends establishing chronicity by reviewing past measurements of GFR, creatinine, and urinalysis; imaging findings showing reduced kidney size or cortical thinning; or repeat measurements over 3 months to determine the cause of renal dysfunction in patients with impaired renal function 3
A BUN/creatinine ratio >35 indicates pre-renal azotemia, suggesting volume depletion, heart failure, or decreased renal perfusion, according to the European Heart Journal 2
Evaluate for reversible causes including hypotension, dehydration, excessive diuretic use, NSAIDs, renal artery stenosis, and other nephrotoxic medications, as recommended by the European Heart Journal 1, 2

The European Heart Journal recommends continuing ACE inhibitors/ARBs if creatinine increases up to 30% and stabilizes within 2 months, as this acute rise is strongly associated with long-term renal protection 2
Discontinue ACE inhibitors/ARBs only if creatinine rises >30% above baseline, continues to worsen progressively beyond 2 months, reaches >500 μmol/L (5 mg/dL), or refractory hyperkalemia (>5.6 mmol/L) develops, according to the European Heart Journal 1, 2
For serum creatinine >250 μmol/L (2.5 mg/dL), specialist nephrology supervision is recommended by the European Heart Journal 1, 2

The European Heart Journal recommends using loop diuretics preferentially when creatinine clearance <30 mL/min, as thiazides become ineffective at this level 1, 4
Avoid excessive ultrafiltration and volume depletion, as episodes of intravascular volume depletion accelerate loss of residual kidney function, according to the American Journal of Kidney Diseases 5
Consider twice-daily dosing of loop diuretics over once-daily for better efficacy, as recommended by Kidney International 4

The Kidney International recommends targeting systolic blood pressure <120 mmHg using standardized office measurement, although this target applies to most patients with CKD, though formally not validated specifically in all glomerular diseases 4
Uptitrate ACE inhibitors or ARBs to maximally tolerated doses as first-line therapy for both hypertension and proteinuria, according to Kidney International 4
Control of severe hypertension can sometimes improve residual kidney function enough to allow discontinuation of dialysis, as reported by the American Journal of Kidney Diseases 5

The European Heart Journal recommends implementing systematic monitoring to detect progression and medication toxicity, including monitoring renal function and electrolytes within the first few weeks after starting or adjusting ACE inhibitors/ARBs 1
Use both creatinine-based eGFR (eGFRcr) and cystatin C-based eGFR (eGFRcr-cys) when eGFRcr is less accurate and clinical decisions depend on precise GFR, according to Kidney International 3
Monitor for hyperkalemia, especially with concurrent use of ACE inhibitors/ARBs, aldosterone antagonists, potassium-sparing diuretics, or potassium supplements, as recommended by the European Heart Journal and Kidney International 1, 4

Refer to nephrology for progressive decline in renal function despite appropriate management, according to Praxis Medical Insights 2
Refer to nephrology for serum creatinine >250 μmol/L (2.5 mg/dL), as recommended by the European Heart Journal and Praxis Medical Insights 1, 2
Refer to nephrology for significant proteinuria or abnormal urinalysis suggesting intrinsic renal disease, according to Praxis Medical Insights 2
Refer to nephrology for uncertainty about cause of renal dysfunction requiring kidney biopsy consideration, as recommended by Kidney International 3

The American Journal of Kidney Diseases recommends avoiding nephrotoxic agents including NSAIDs, aminoglycosides, and radiocontrast when possible 5
Maintain hemodynamic stability during any dialysis procedures by avoiding hypotension through reduced dialysate temperature, increased dialysate sodium, or midodrine administration, according to the American Journal of Kidney Diseases 5
Restrict dietary sodium to <2.0 g/day (<90 mmol/day) to reduce volume overload and blood pressure, as recommended by Kidney International 4
Adjust doses of renally-cleared medications (e.g., digoxin) to avoid toxicity, according to the European Heart Journal 1