What is the initial treatment approach for a patient with acute kidney injury?

Initial Treatment of Acute Kidney Injury

Management of AKI should be based on comprehensive clinical assessment including the specific cause, volume status, hemodynamic stability, electrolyte disturbances, and trends in kidney function—not solely on AKI stage or creatinine levels. 1, 2

Immediate Assessment and Stabilization

Volume Status and Hemodynamic Management

• Assess volume status immediately to determine if the patient is hypovolemic, euvolemic, or hypervolemic, as this fundamentally directs initial fluid management 3, 4
• Administer isotonic crystalloids (preferably balanced crystalloids like lactated Ringer's) rather than colloids for volume expansion in hypovolemic patients, targeting euvolemia 1, 3, 2
• In septic patients specifically, deliver at least 30 mL/kg of crystalloid within the first 3 hours 2
• Avoid starch-containing fluids entirely as they cause harm in AKI patients 1
• Use vasopressors (norepinephrine first-line) in conjunction with fluids for patients with vasomotor shock, targeting mean arterial pressure ≥65 mmHg 1, 2
• Never use dopamine for AKI prevention or treatment—it is ineffective and potentially harmful 1, 2

Medication Review and Adjustment

• Discontinue all nephrotoxic medications immediately, including NSAIDs, aminoglycosides, and contrast agents when possible 1, 3, 4
• Hold ACE inhibitors, ARBs, and diuretics temporarily until volume status is clarified 4
• Adjust all medication dosages based on current renal function, not baseline values 4
• For essential nephrotoxic drugs (e.g., antibiotics in sepsis), never reduce loading doses—only adjust maintenance doses, as subtherapeutic levels lead to treatment failure 2
• Perform therapeutic drug monitoring when using aminoglycosides 1

Electrolyte and Acid-Base Management

• Monitor and correct electrolyte abnormalities, particularly hyperkalemia and metabolic acidosis 3, 2
• Implement strict intake/output monitoring with daily weights 3
• Target blood glucose 110-149 mg/dL using protocolized insulin therapy 2

Diagnostic Workup

• Perform urgent renal ultrasonography to rule out obstructive causes, especially in older men with prostatic hypertrophy 3, 5
• Obtain urinalysis, fractional excretion of sodium, complete blood count, and serum electrolytes 5, 6
• Use KDIGO criteria to classify AKI severity: Stage 1 (creatinine 1.5-1.9× baseline or ≥0.3 mg/dL increase), Stage 2 (2.0-2.9× baseline), Stage 3 (≥3.0× baseline or ≥4.0 mg/dL or dialysis initiated) 3, 4

Renal Replacement Therapy Indications

Initiate RRT emergently only for life-threatening indications, not based on creatinine level or AKI stage alone 1, 2:

• Severe refractory hyperkalemia (>6.5 mmol/L unresponsive to medical management) 3, 2
• Severe metabolic acidosis (pH <7.1-7.2) refractory to medical therapy 3, 4, 2
• Volume overload causing pulmonary edema or respiratory compromise 3, 4
• Uremic complications (encephalopathy, pericarditis, pleuritis) 5

RRT Modality Selection

• For hemodynamically unstable patients, use continuous RRT (CRRT) rather than intermittent hemodialysis, targeting effluent volume of 20-25 mL/kg/hour 1, 3, 2
• For stable patients, intermittent hemodialysis with Kt/V ≥1.2 per treatment three times weekly is appropriate 1
• Use regional citrate anticoagulation for CRRT in patients without contraindications 1
• Place uncuffed non-tunneled dialysis catheter via right internal jugular or femoral vein (avoid subclavian) 1

Nephrology Consultation Criteria

Consult nephrology immediately for 4, 6:

• Stage 2 or 3 AKI (creatinine ≥2.0× baseline)
• Persistent AKI despite initial management after 48-72 hours
• Severe metabolic acidosis (pH <7.2 or bicarbonate <12 mEq/L)
• Refractory hyperkalemia
• AKI without clear cause
• Pre-existing stage 4 or higher chronic kidney disease

Nutritional Support

• Provide total energy intake of 20-30 kcal/kg/day 2
• Protein requirements: 0.8-1.0 g/kg/day in non-catabolic AKI without dialysis; 1.0-1.5 g/kg/day in patients on RRT; up to 1.7 g/kg/day in hypercatabolic patients on CRRT 2

Critical Pitfalls to Avoid

• Never use diuretics, dopamine, or recombinant human IGF-1 to prevent or treat AKI—they are ineffective 1
• Never withhold or delay necessary antibiotics due to nephrotoxicity concerns in septic patients—treating the underlying infection takes absolute priority 2
• Avoid albumin in traumatic brain injury patients (associated with harm), but albumin is appropriate for spontaneous bacterial peritonitis and large-volume paracentesis in liver disease 1
• Do not initiate RRT based solely on creatinine elevation or AKI stage 2

Follow-Up Requirements

• Stage 3 AKI requires follow-up within 1-2 weeks due to high risk of CKD progression 4
• All AKI patients should be evaluated at 3 months to assess for CKD development 4
• More intensive monitoring is needed for patients with pre-existing CKD, heart failure, or incomplete recovery at hospital discharge 1, 4