What is the best course of action for an elderly male patient with rapidly worsening impaired renal function, edema in both lower extremities, and confusion?

Immediate Hospitalization and Urgent Nephrology Consultation Required

This elderly male patient requires immediate hospital admission for acute kidney injury (AKI) on chronic kidney disease (CKD), with urgent nephrology consultation to determine the need for renal replacement therapy. The creatinine rise from 1.53 to 2.9 mg/dL over 11 days represents a near-doubling of creatinine, indicating acute-on-chronic renal failure, and the combination of bilateral lower extremity edema and confusion suggests uremic encephalopathy with volume overload 1, 2.

Critical Initial Assessment

Calculate the estimated GFR immediately using the Cockcroft-Gault or CKD-EPI equation, as serum creatinine alone dramatically underestimates renal impairment in elderly patients due to decreased muscle mass 1, 3. With a creatinine of 2.9 mg/dL in an elderly male, the eGFR is likely <30 mL/min/1.73 m², representing Stage 4-5 CKD 3, 2.

Identify Reversible Causes of AKI

Immediately evaluate for the following precipitants 1, 2:

• Volume depletion or overload: The bilateral edema suggests volume overload, but assess for concurrent dehydration from poor oral intake 1
• Nephrotoxic medications: Review all medications and immediately discontinue NSAIDs, which can precipitate acute-on-chronic kidney injury 1, 3, 2
• Urinary obstruction: Check for prostatic obstruction in this elderly male, which is a common reversible cause 1
• Cardiac dysfunction: The edema may indicate heart failure with cardiorenal syndrome, where renal venous congestion impairs kidney function 1, 4, 5
• Infection or sepsis: Acute illness can precipitate AKI and cause confusion 1
• Medication accumulation: If the patient is on metformin, discontinue immediately as it is contraindicated with eGFR <30 mL/min/1.73 m² due to risk of fatal lactic acidosis 6

Immediate Management Steps

1. Hospitalization for Monitoring and Treatment

Admit the patient for continuous monitoring of renal function, fluid status, and mental status 2, 7. The confusion may represent uremic encephalopathy, which requires urgent intervention 7, 8.

2. Nephrology Consultation

Refer urgently to nephrology, as patients with eGFR <30 mL/min/1.73 m² meet absolute criteria for specialist consultation to determine etiology, assess progression risk, and establish whether dialysis is needed 2.

3. Volume Management

• For volume overload with edema: Initiate loop diuretics (furosemide) to reduce pulmonary and peripheral congestion, even in the setting of renal dysfunction 1, 5
• Monitor response closely: If diuretics fail to produce adequate urine output, this may indicate need for dialysis 8, 5
• Avoid excessive diuresis: Balance volume reduction against worsening renal function, as overly aggressive diuresis can cause prerenal azotemia 4

4. Medication Review and Adjustment

Immediately review and adjust all medications for eGFR <30 mL/min/1.73 m² 3, 2:

• Stop metformin if prescribed (contraindicated with eGFR <30) 6
• Discontinue all NSAIDs completely 3, 2
• Hold ACE inhibitors/ARBs temporarily if acute decline is suspected from these agents, particularly if bilateral renal artery stenosis is possible 1
• Reduce doses of renally-cleared medications to prevent drug accumulation and toxicity 1, 2

5. Laboratory Monitoring

Obtain the following urgently 2, 7:

• Complete metabolic panel: Assess for hyperkalemia, metabolic acidosis, and uremia
• Urinalysis with microscopy: Evaluate for intrinsic renal disease
• Renal ultrasound: Rule out obstruction
• BNP or NT-proBNP: If heart failure is suspected 5
• Serial creatinine measurements: Monitor trajectory of renal function

6. Address Confusion

The confusion likely represents uremic encephalopathy from accumulated toxins 7. This should improve with treatment of the underlying renal failure, but also rule out:

• Hypoxemia from pulmonary edema
• Electrolyte abnormalities (hyponatremia, hyperkalemia)
• Medication toxicity from accumulated drugs
• Concurrent infection or sepsis

Dialysis Considerations

Prepare for potential urgent dialysis if the patient develops 7, 9:

• Severe hyperkalemia (>6.5 mEq/L) unresponsive to medical management
• Metabolic acidosis (pH <7.2)
• Volume overload refractory to diuretics
• Uremic pericarditis
• Progressive uremic encephalopathy despite conservative management

Common Pitfalls to Avoid

• Do not rely on serum creatinine alone in elderly patients—it dramatically underestimates the severity of renal impairment 1, 3
• Do not continue metformin if eGFR is <30 mL/min/1.73 m²—this can cause fatal lactic acidosis 6
• Do not assume the edema is purely cardiac—renal venous congestion from right heart failure can worsen kidney function 1, 4
• Do not delay nephrology consultation—patients with Stage 4-5 CKD require specialist input for optimal management 2
• Do not withhold diuretics due to renal dysfunction—loop diuretics remain appropriate for volume overload even with significant renal impairment 5

Prognosis and Follow-up

If this represents acute tubular necrosis or prerenal azotemia from a reversible cause, renal function may recover with appropriate treatment 7. However, the mortality risk is high (50-70%) in hospitalized patients with AKI requiring intensive management 7. After stabilization, the patient will require close nephrology follow-up every 3 months with monitoring of eGFR and consideration for renal replacement therapy planning 2.