Management of Protein Energy Wasting in Chronic Kidney Disease
Protein energy wasting (PEW) in CKD requires a multimodal treatment strategy centered on optimizing dietary protein and energy intake, correcting metabolic disturbances (particularly acidosis and inflammation), and implementing anabolic interventions when oral intake alone is insufficient. 1
Core Nutritional Management Strategy
Protein Intake Targets
The protein prescription must be tailored to CKD stage, dialysis status, and metabolic stability:
- Non-dialysis CKD G3-G5 (metabolically stable): Maintain 0.8 g/kg body weight/day 1, 2
- CKD patients on conventional intermittent hemodialysis: Increase to 1.2-1.5 g/kg/day to offset dialysate amino acid losses 1, 3
- Critically ill CKD patients on continuous renal replacement therapy: Target 1.5-1.7 g/kg/day, potentially up to 2.0-2.5 g/kg/day to achieve positive nitrogen balance 1, 3
Critical caveat: Do NOT prescribe low or very low-protein diets (<0.6 g/kg/day) in metabolically unstable patients with PEW, as this will worsen protein depletion 1. The exception is supervised very low-protein diets (0.3-0.4 g/kg/day) supplemented with ketoacid analogs (total protein equivalence 0.6 g/kg/day) in willing, metabolically stable patients at high risk of kidney failure 1, 4.
Energy Intake Requirements
Adequate caloric intake is essential to prevent protein catabolism for energy:
- Target 25-35 kcal/kg/day to maintain positive energy balance 1, 4
- Avoid overfeeding, which does not improve nitrogen balance and may worsen metabolic derangements 1
Special Population Considerations
Older adults with frailty or sarcopenia: Consider HIGHER protein and calorie targets than standard CKD recommendations to prevent muscle wasting 1. The risk of malnutrition outweighs theoretical concerns about CKD progression in this population.
Children with CKD: Do NOT restrict protein intake—target the upper end of normal range for healthy children to promote optimal growth 1.
Correcting Metabolic Disturbances
Metabolic Acidosis Management
Normalize serum bicarbonate to at least 23 mEq/L in dialysis patients and to normal range in non-dialysis CKD patients 5. Acidosis directly stimulates protein catabolism and muscle breakdown through the ubiquitin-proteasome pathway 1.
Inflammation Control
Address systemic inflammation, which is a primary driver of PEW through cytokine-mediated catabolism 1, 6. While anti-inflammatory interventions are emerging therapies, the current focus should be on treating underlying inflammatory conditions (infections, inadequate dialysis, volume overload) 1.
Hormonal Deficiencies
Evaluate and treat hormonal abnormalities that contribute to catabolism, including insulin resistance and growth hormone deficiency 1.
Nutritional Supplementation Strategies
When oral dietary intake from regular meals cannot maintain adequate nutritional status, implement supplementation in this hierarchical order:
Oral Nutritional Supplements (First-Line)
Oral supplements are preferred due to proven efficacy, safety, and compliance 1. Use high-protein, high-calorie formulations to meet targets without excessive fluid volume.
Enteral Nutrition (Second-Line)
For patients unable to meet needs orally, use enteral feeding via nasogastric or gastrostomy tube 1. Consider concentrated renal formulas (70-80 g protein/L) to minimize fluid overload 3.
Parenteral Nutrition (Third-Line)
Intradialytic parenteral nutrition (IDPN) or total parenteral nutrition for patients who cannot tolerate enteral routes 1. IDPN provides 250-300 kcal and 15-20 g amino acids per dialysis session.
Anabolic Interventions
Anabolic strategies combined with nutritional support improve protein stores more effectively than nutrition alone:
Exercise Programs
Prescribe structured resistance and aerobic exercise to stimulate muscle protein synthesis and reduce catabolism 1. While definitive mortality benefit is not yet proven, exercise improves muscle mass and functional status 5.
Pharmacologic Anabolic Agents
Consider the following when nutritional interventions alone are insufficient:
- Anabolic steroids: Improve lean body mass and muscle strength in combination with nutritional support 1
- Growth hormone: Increases protein synthesis but requires careful monitoring for side effects 1
- Appetite stimulants: Emerging therapies for anorexia-associated PEW 1
Optimizing Dialysis Prescription
For dialysis patients, ensure adequate dialysis dose to reduce uremic toxin burden, which suppresses appetite and promotes catabolism 1. However, do NOT reduce protein intake to avoid dialysis initiation—this worsens PEW and outcomes 3.
Monitoring and Assessment
Use the Malnutrition-Inflammation Score (KALANTAR Score) to systematically assess nutritional risk and track response to interventions 7, 5. This comprehensive tool predicts outcomes better than single parameters.
Monitor these key parameters:
- Serum albumin (though influenced by inflammation, remains prognostically important) 8, 7
- Body mass index and serial weight measurements 8
- Muscle mass assessment (DEXA, bioimpedance, or anthropometry) 8, 5
- Dietary intake records to ensure adherence to protein and energy targets 1
- Nitrogen balance in critically ill patients on dialysis 1, 3
Critical Pitfalls to Avoid
Do not continue outpatient protein restriction during acute illness or hospitalization—catabolic states fundamentally change protein requirements upward 3, 6. The metabolic stress of acute illness, inflammation, and immobilization creates extensive muscle protein breakdown that cannot be reversed by protein restriction 1.
Do not use actual body weight for protein calculations in obese patients—use pre-hospitalization or usual body weight 1, 3. Actual body weight overestimates requirements in dialysis patients and underestimates needs in non-dialysis patients.
Do not restrict protein to manage rising BUN—manage azotemia with appropriate dialysis dosing, not nutritional deprivation 3. Protein restriction in the setting of PEW accelerates muscle wasting and worsens outcomes.
Malnutrition is a far greater threat than obesity in CKD patients 7. The obesity paradox (better outcomes with higher BMI) becomes increasingly pronounced in advanced CKD and dialysis populations, so aggressive weight loss should be avoided in established PEW 5.
Evidence Limitations
While epidemiological data strongly link improved nutritional biomarkers with better survival, no large randomized controlled trials have definitively proven that treating PEW reduces mortality and morbidity 1, 9. However, the consistent observational evidence, biological plausibility, and improvements in quality of life justify aggressive PEW prevention and treatment in clinical practice 9.