What is the management approach for renal infarct?

Management of Renal Infarction

The management of renal infarction centers on immediate hemodynamic stabilization with IV normal saline, diagnostic confirmation via contrast-enhanced CT, and anticoagulation therapy with heparin followed by warfarin, while avoiding potassium-containing fluids and carefully monitoring renal function.

Immediate Stabilization and Assessment

Assess hemodynamic stability immediately upon presentation, looking for signs of shock including hypotension, tachycardia, or respiratory distress 1. The initial response to resuscitation determines the entire management pathway.

Fluid Resuscitation Strategy

• Provide aggressive fluid resuscitation with normal saline (0.9%) to maintain renal perfusion and prevent further kidney injury 2
• Avoid potassium-containing balanced salt solutions such as Lactated Ringer's, as potassium levels may increase markedly even with intact renal function 2
• Estimate glomerular filtration rate (eGFR) as soon as possible after admission to guide medication dosing and contrast use 1, 3

Monitoring Parameters

• Monitor urine output regularly to detect oliguria or anuria 2
• Check electrolytes frequently, with particular attention to potassium levels 2
• Measure serum lactate dehydrogenase (LDH) and white blood cell count, which are typically elevated in renal infarction (mean LDH 1,570 IU/L, WBC 12,988/μL) 4

Diagnostic Confirmation

IV contrast-enhanced CT with immediate and delayed images is the definitive diagnostic modality for suspected renal infarction 2, 1. This should be performed urgently once hemodynamic stability is achieved.

• Ensure proper hydration before and after contrast administration to minimize the risk of contrast-induced nephropathy 1, 3
• Limit the dose of contrast agents when possible 3
• Duplex ultrasound may be used as first-line imaging when renal artery disease is suspected, but is less sensitive than CT 2

Anticoagulation Therapy

The cornerstone of medical management is anticoagulation with heparin followed by warfarin 5, 4. This approach is supported by the largest case series showing that 342 patients received heparin and 330 received warfarin 5.

Anticoagulation Protocol

• Initiate intravenous heparin in hemodynamically stable patients without contraindications 5, 4
• Transition to oral warfarin for long-term anticoagulation 5
• Consider antiplatelet therapy with aspirin in patients with atherosclerotic renal artery disease 2
• In select cases, thrombolytic therapy with urokinase may be considered, though evidence is limited (19 patients in one series) 5

Dosing Adjustments in Renal Dysfunction

Pay meticulous attention to proper dosing of antithrombotic medications in patients with renal dysfunction 1, 3. The following adjustments apply when creatinine clearance is <60 mL/min:

• Aspirin and clopidogrel: No dose adjustment required 3
• Unfractionated heparin: No adjustment of bolus dose 3
• Enoxaparin: No adjustment of bolus dose, but following thrombolysis in patients with creatinine clearance <30 mL/min, subcutaneous doses should be given once every 24 hours instead of twice daily 3

Intervention for Hemodynamic Instability

For hemodynamically unstable patients with no or transient response to resuscitation, immediate intervention is warranted 1, 2.

Intervention Options

• Surgical exploration for patients with severe renal vascular injuries without self-limiting bleeding 2
• Angioembolization as an alternative to surgery 1, 2
• In patients with solitary kidney and moderate to severe renal trauma with arterial contrast extravasation on CT, angiography with super-selective angioembolization should be considered as first choice 2

Prognosis and Outcomes

Despite aggressive treatment, renal infarction carries significant morbidity. In the largest case series of 438 patients:

• 5% died during initial hospitalization 5
• 20.1% developed acute kidney injury (defined as creatinine increase ≥0.3 mg/dL within 48 hours) 5
• 10.9% developed new-onset eGFR <60 mL/min/1.73m² 5
• 2.1% progressed to end-stage renal disease requiring dialysis 5
• 2.8% had recurrent infarction during median 20-month follow-up 5

Initial renal function is the strongest predictor of poor outcome (OR=0.949; 95% CI 0.918-0.980; p=0.002), along with lack of prior oral anticoagulation (OR=0.135; 95% CI 0.032-0.565; p=0.006) 6.

Common Pitfalls

Renal infarction is frequently misdiagnosed as renal colic, pyelonephritis, or acute abdomen, with time from admission to definitive CT diagnosis ranging from 24 hours to 6 days 4. The classic triad of flank pain, hematuria (present in all cases on urine reagent strips), and elevated LDH with leukocytosis should raise immediate suspicion, particularly in patients with atrial fibrillation or other thromboembolic risk factors 4.

Cardiogenic origins account for 55.7% of cases, with atrial fibrillation being the most common predisposing factor 5. However, 30.1% of cases are idiopathic, emphasizing the need for high clinical suspicion even without obvious risk factors 5.