Management of Impaired Renal Function

Initial Assessment and Classification

The American College of Cardiology recommends determining if the elevated creatinine represents acute kidney injury (AKI) or chronic kidney disease (CKD) by comparing with previous values if available 3
Classify severity using modified KDIGO criteria, with Stage 1 being an increase in serum creatinine ≥26.5 mmol/L or 1.5-2 fold from baseline, Stage 2 being an increase 2-3 fold from baseline, and Stage 3 being an increase >3 fold from baseline or serum creatinine ≥353.6 mmol/L 1, 4, 5
Calculate estimated GFR using appropriate equations (MDRD or CKD-EPI), as serum creatinine alone is an inadequate measure of renal function, especially in elderly or those with reduced muscle mass 6

Withdraw nephrotoxic medications, including NSAIDs, certain antibiotics, and other nephrotoxic agents, and adjust doses of medications cleared by kidneys based on estimated GFR 1, 2, 5, 6
Assess and correct volume status, providing plasma volume expansion if hypovolemic, and avoiding excessive fluid administration to prevent pulmonary edema if euvolemic or hypervolemic 1, 3
Monitor renal function and electrolytes, checking serum creatinine, electrolytes, and urine output regularly, and monitoring for hyperkalemia, metabolic acidosis, and other electrolyte abnormalities 2, 6, 7

For ACE inhibitors or ARBs, use with caution and monitor closely when creatinine ≥2.0-2.5 mg/dL, and reduce initial dose to half of the usual recommended dose for patients with creatinine clearance ≤30 mL/min 8
For aldosterone antagonists, they are not recommended when creatinine >2.5 mg/dL or creatinine clearance <30 mL/min, and consider reduced initial dose (spironolactone 12.5 mg daily) if creatinine is 1.6-2.5 mg/dL 8

For Hepatorenal Syndrome, administer vasoconstrictors (terlipressin as first-line therapy) combined with albumin, and provide volume expansion with albumin (1g/kg) for 48 hours in stage 2-3 AKI 1, 4, 5
For Other Causes of AKI, identify and treat underlying causes, optimize blood pressure control with target <140/90 mmHg, and consider renal replacement therapy for severe metabolic acidosis, hyperkalemia, pulmonary edema, or uremic symptoms 2, 3, 6, 8, 9

Monitor serum creatinine, electrolytes, and urine output regularly, and check creatinine every 24-48 hours until stabilized for AKI, and at intervals based on stage and stability for CKD 2, 6, 7
Assess for complications of renal dysfunction, such as anemia, metabolic acidosis, etc. 2, 6

Uncertain etiology of kidney disease, progressive decline in renal function, severe electrolyte abnormalities, eGFR <30 mL/min/1.73m², or persistent significant proteinuria 2, 3, 6