Protein Supplementation in Acute Kidney Injury

Introduction to Protein Targets

The American Society for Nutrition recommends that protein supplementation should not be restricted in patients with Acute Kidney Injury (AKI), and adequate to high protein intake is essential to prevent muscle wasting and improve survival, with specific targets based on illness severity and renal replacement therapy status 1

The Clinical Nutrition society recommends that protein prescription shall not be reduced to avoid or delay kidney replacement therapy (KRT) initiation in critically ill patients with AKI, with a Grade A recommendation and 96% consensus 1

For non-critically ill AKI patients not on dialysis, the target protein intake is 0.8-1.0 g/kg body weight/day, using pre-hospitalization or usual body weight, not actual body weight 1, 2, 3
For critically ill AKI patients not on dialysis, the target protein intake is 1.0 g/kg/day, gradually increasing up to 1.3 g/kg/day if tolerated, due to the catabolic state of critical illness 1, 2, 4
For AKI patients on intermittent hemodialysis, the target protein intake is 1.3-1.5 g/kg/day, reflecting amino acid losses during dialysis sessions 1, 2, 3, 4
For AKI patients on Continuous Renal Replacement Therapy (CRRT), the target protein intake is 1.5-1.7 g/kg/day, with some evidence suggesting targets up to 2.0-2.5 g/kg/day may be beneficial for achieving positive nitrogen balance 1, 2, 3, 4

The American Society for Parenteral and Enteral Nutrition recommends that protein prescription should ideally be guided by protein catabolic rate rather than body weight-based estimates alone, with normalized protein catabolic rates in AKI patients on KRT ranging from 1.2-2.1 g/kg/day 2, 3, 4
Enteral nutrition is preferred when possible, with consideration of concentrated renal formulas (70-80 g protein/L) to reduce fluid overload while meeting protein targets 1, 6, 7

Using actual body weight for calculations overestimates protein requirements in patients on KRT and underestimates needs in those not on dialysis, so pre-hospitalization or usual body weight should be used instead 1, 3
Continuing outpatient protein restriction in CKD patients during hospitalization for acute illness is not recommended, as the catabolic state of acute illness fundamentally changes protein requirements 5, 6
Restricting protein due to rising BUN is not recommended, as the accumulation of nitrogenous waste products should be managed with appropriate KRT dosing, not protein restriction 1, 6

Calculating protein catabolic rate when feasible, especially in patients on KRT, and monitoring nitrogen balance to guide protein dosing adjustments are recommended 1, 3, 4
Assessing for micronutrient deficiencies (selenium, zinc, copper) which are increased during KRT is also recommended 6