Wasting in chronic kidney disease

Abstract

Wasting/cachexia is prevalent among patients with chronic kidney disease (CKD). It is to be distinguished from malnutrition, which is defined as the consequence of insufficient food intake or an improper diet. Malnutrition is characterized by hunger, which is an adaptive response, whereas anorexia is prevalent in patients with wasting/cachexia. Energy expenditure decreases as a protective mechanism in malnutrition whereas it remains inappropriately high in cachexia/wasting. In malnutrition, fat mass is preferentially lost and lean body mass and muscle mass is preserved. In cachexia/wasting, muscle is wasted and fat is relatively underutilized. Restoring adequate food intake or altering the composition of the diet reverses malnutrition. Nutrition supplementation does not totally reverse cachexia/wasting. The diagnostic criteria of cachexia/protein–energy wasting in CKD are considered. The association of wasting surrogates, such as serum albumin and prealbumin, with mortality is strong making them robust outcome predictors. At the patient level, longevity has consistently been observed in patients with CKD who have more muscle and/or fat, who report better appetite and who eat more. Although inadequate nutritional intake may contribute to wasting or cachexia, recent evidence indicates that other factors, including systemic inflammation, perturbations of appetite-controlling hormones from reduced renal clearance, aberrant neuropeptide signaling, insulin and insulin-like growth factor resistance, and metabolic acidosis, may be important in the pathogenesis of CKD-associated wasting. A number of novel therapeutic approaches, such as ghrelin agonists and melanocortin receptor antagonists are currently at the experimental level and await confirmation by randomized controlled clinical trials in patients with CKD-associated cachexia/wasting syndrome.

Vitamin D, a modulator of musculoskeletal health in chronic kidney disease

“…Vitamin D deficiency is common in patients with chronic kidney disease (CKD),4 a population in whom muscle wasting and weakness are also highly prevalent 5, 6, 7. Observational studies have shown that circulating 25‐hydroxyvitamin D [25(OH)D] levels are reduced in parallel to the severity of muscle symptoms 8.…”

“…These observations collectively imply an integrated role of vitamin D for bone and muscle health. Such a role may have substantial clinical implications, especially for CKD patients, in which musculoskeletal alterations and their complications, including muscle pain and weakness, sarcopenia, fatigability, reduced exercise tolerance, fractures, and falls, adversely affect quality of life and survival 12, 13, 14, 15, 16, 17…”

Loss of muscle mass: Current developments in cachexia and sarcopenia focused on biomarkers and treatment

“…[1][2][3] A serious complication of these chronic illnesses is cachexia. Cachexia is defined as weight loss greater than 5% of body weight in 12 months or less in the presence of chronic illness or as a body mass index (BMI) lower than 20 kg/m 2 .…”

Distinguishing Between Cachexia, Sarcopenia and Protein Energy Wasting in End-Stage Renal Disease Patients on Dialysis

“…7 Significant progress has been made defining cachexia and its associated clinical characteristics in patients with cancer. An agreed definition and classification of cancer cachexia 8 has contributed to enhanced standardization of screening, staging assessment and management.…”