Why can our legs feel weak with CKD

Chronic kidney disease (CKD) can lead to leg weakness through a complex interplay of several factors.¹ Here's a breakdown of the key reasons:

• Muscle Wasting (Sarcopenia):²
  • CKD can disrupt the body's protein balance, leading to increased muscle breakdown and decreased muscle protein synthesis.³ This results in a loss of muscle mass and strength, particularly in the legs.⁴
  • Factors contributing to this include:
    • Metabolic acidosis: An imbalance of acids in the body.⁵
    • Inflammation: Chronic inflammation associated with CKD.⁶
    • Hormonal imbalances.⁷
    • Reduced physical activity.⁸
    • Protein-energy wasting.⁹
• Anemia:
  • The kidneys produce a hormone called erythropoietin, which stimulates red blood cell production.¹⁰ In CKD, reduced erythropoietin production leads to anemia (low red blood cell count).¹¹
  • Anemia causes fatigue and weakness, as the muscles don't receive enough oxygen.¹²
• Electrolyte Imbalances:
  • Damaged kidneys struggle to regulate electrolyte levels, such as potassium, calcium, and phosphate.¹³
  • High potassium (hyperkalemia) can cause muscle weakness.¹⁴
  • Imbalances in calcium and phosphate can affect bone health, further contributing to weakness.
• Nerve Damage (Peripheral Neuropathy):
  • The buildup of waste products in the blood due to CKD can damage nerves, particularly in the extremities.
  • This can cause muscle weakness, numbness, tingling, and pain in the legs and feet.¹⁵
• Reduced Physical Activity:
  • Fatigue and other CKD symptoms can lead to decreased physical activity, further contributing to muscle weakness and deconditioning.
• Mitochondrial Dysfunction:
  • Studies have shown that CKD can negatively impact the mitochondria within the muscle cells.¹⁶ Mitochondria are responsible for energy production within the cells.¹⁷ Therefore when they are not working correctly, it leads to muscle weakness.

In essence, CKD creates a cascade of physiological changes that weaken muscles, impair nerve function, and reduce overall energy levels, resulting in leg weakness.¹⁸