How to improve muscle weakness in patients with impaired renal function?

Improving Muscle Weakness in Patients with Impaired Renal Function

Dialysis patients should increase protein intake to 1.0-1.2 g/kg/day combined with resistance training to prevent and reverse muscle loss, while pre-dialysis CKD patients require individualized protein management based on their risk of progression to end-stage kidney disease. 1

Protein Management Strategy

For Dialysis Patients (Hemodialysis and Peritoneal Dialysis)

• Increase protein intake to prevent muscle wasting, as dialysis patients lose amino acids during treatment and have accelerated protein catabolism 1, 2
• Target 1.0-1.2 g/kg body weight per day of high-quality protein from sources low in saturated fat and cholesterol 1, 2
• Select lean meats, poultry, fish, and legumes as primary protein sources 2
• Oral nutritional supplementation (ONS) providing 475 kcal and 21.7 g protein daily significantly increases quadriceps muscle thickness by 8.3% and cross-sectional area by 4.5% over 6 months 3

For Pre-Dialysis CKD Patients

The protein prescription depends critically on ESKD progression risk 4:

High-Risk Patients (Stage G4-G5):

• Maintain protein restriction at 0.6-0.8 g/kg/day to slow CKD progression 5, 4
• Must combine with resistance training to counteract catabolic effects 5

Low-Risk Patients (Stage G3 with proteinuria <0.5 g/day and eGFR decline <3.0 mL/min/1.73 m²/year):

• Can liberalize protein to 0.8-1.0 g/kg/day to address sarcopenia 4
• Avoid exceeding 1.5 g/kg/day even when loosening restrictions 4

Resistance Training Protocol

Resistance training is essential and non-negotiable for all renal patients with muscle weakness, as it directly counteracts uremic catabolism 5:

• Resistance training increases total body potassium by 4%, type I muscle fiber area by 24%, and type II muscle fiber area by 22% in CKD patients on low-protein diets 5
• Improves muscle strength by 32% compared to 13% decline without training 5
• Enhances protein utilization, increases serum prealbumin, and reduces leucine oxidation 5
• Protein supplementation alone without exercise has limited benefit—the combination is required for meaningful improvement 4

Nutritional Assessment and Monitoring

Initial Assessment

• Perform handgrip strength testing as the primary functional assessment tool, as values <10 kg at discharge and <15 kg one month post-discharge predict mortality 1
• Use ultrasound imaging to assess quadriceps muscle thickness and cross-sectional area, as it is reliable and unaffected by fluid shifts common in renal patients 1
• Calculate creatinine index to assess muscle mass, as low serum creatinine (<10 mg/dL in dialysis patients) indicates muscle wasting and increased mortality risk 1, 6
• Apply the Malnutrition-Inflammation Score (MIS) to predict nutritional risk and mortality 7

Ongoing Monitoring

• Reassess nutritional status at least every 6 months with trained renal dietitians 2
• Monitor serum prealbumin (target ≥30 mg/dL) as it correlates with mortality and responds to nutritional intervention 1
• Track body composition changes using ultrasound rather than BMI or weight alone, as fluid overload masks true nutritional status 1

Energy Requirements

Adequate caloric intake is critical to prevent protein-energy wasting 7, 8:

• Ensure sufficient energy intake to maintain neutral or positive nitrogen balance 8
• Energy supplementation is necessary when protein is restricted to avoid using dietary protein for energy 7
• Higher caloric intake is associated with maintaining nitrogen balance in CKD patients 8

Oral Nutritional Supplementation

For dialysis patients with documented protein-energy wasting:

• Provide renal-specific ONS delivering approximately 475 kcal and 21.7 g protein daily for at least 6 months 3
• Combine ONS with nutrition counseling, as this combination reduces PEW prevalence from baseline to 24.1% and improves MIS scores 3
• ONS increases dry weight, mid-thigh girth, serum prealbumin, and normalized protein catabolic rate 3

L-Carnitine Supplementation

L-carnitine may be considered for selected dialysis patients with specific symptoms 9:

• Can improve subjective symptoms including malaise, muscle weakness, intradialytic cramps, and hypotension 9
• Typical dosing: 1 mg/kg to 2 g at the end of each dialysis session, or oral doses of 10 mg/kg/day to 3 g/day 9
• However, routine use is not supported by evidence—reserve for symptomatic patients only 9
• Be aware of gastrointestinal side effects (nausea, vomiting, diarrhea) at doses around 3 g/day 9

Additional Metabolic Considerations

• Correct metabolic acidosis by normalizing serum bicarbonate, as acidosis accelerates protein catabolism 7, 8
• Address chronic inflammation, which drives muscle protein degradation in CKD 7, 8
• Manage vitamin D deficiency and hormonal imbalances that contribute to muscle loss 8
• Control phosphorus while maintaining adequate protein intake (typically 10-12 mg phosphorus per gram protein) 2

Critical Pitfalls to Avoid

• Do not rely on BMI or body weight alone in renal patients, as fluid overload and sarcopenic obesity are common 1
• Do not use bioelectric impedance analysis (BIA) in patients with fluid overload or on dialysis, as it provides inaccurate measurements 1
• Do not prescribe protein restriction without concurrent resistance training in patients with established muscle wasting, as this accelerates catabolism 5
• Do not ignore declining serum creatinine levels—this indicates progressive muscle loss and predicts mortality 1, 6
• Preventing protein-energy wasting is more important than treating obesity in renal patients due to reverse epidemiology 7