Sarcopenia in chronic kidney disease: what have we learned so far?

Abstract

The term sarcopenia was first introduced in 1988 by Irwin Rosenberg to define a condition of muscle loss that occurs in the elderly. Since then, a broader definition comprising not only loss of muscle mass, but also loss of muscle strength and low physical performance due to ageing or other conditions, was developed and published in consensus papers from geriatric societies. Sarcopenia was proposed to be diagnosed based on operational criteria using two components of muscle abnormalities, low muscle mass and low muscle function. This brought awareness of an important nutritional derangement with adverse outcomes for the overall health. In parallel, many studies in patients with chronic kidney disease (CKD) have shown that sarcopenia is a prevalent condition, mainly among patients with end stage kidney disease (ESKD) on hemodialysis (HD). In CKD, sarcopenia is not necessarily age-related as it occurs as a result of the accelerated protein catabolism from the disease and from the dialysis procedure per se combined with low energy and protein intakes. Observational studies showed that sarcopenia and especially low muscle strength is associated with worse clinical outcomes, including worse quality of life (QoL) and higher hospitalization and mortality rates. This review aims to discuss the differences in conceptual definition of sarcopenia in the elderly and in CKD, as well as to describe etiology of sarcopenia, prevalence, outcome, and interventions that attempted to reverse the loss of muscle mass, strength and mobility in CKD and ESKD patients.

Maintenance of Skeletal Muscle to Counteract Sarcopenia in Patients with Advanced Chronic Kidney Disease and Especially Those Undergoing Hemodialysis

“…However, many problems remain to be solved. To develop appropriate measures against sarcopenia, it is necessary to obtain an accurate understanding of its prevalence, as various reports have shown a wide range from 4 to 63% of CKD patients [ 16 ], with those findings largely dependent on the methods, cut-off values, and criteria employed. Furthermore, it is also important to consider age- and/or CKD- related muscle histological modifications such as myosteatosis and myofibrosis [ 17 , 18 ], which are described later.…”

Exercise training in patients after kidney transplantation

“…Furthermore, independent of other CV risk factors, obesity at 1-year post-transplant increases the risk for death and graft failure [ 64 ]. Many patients are sarcopenic pre-transplant [ 67 ]. Lean body mass further deteriorates in the early aftermath of transplantation [ 68 ], following which no or only modest improvements take place [ 46 , 69 , 70 ].…”

Optimal Protein Intake in Pre-Dialysis Chronic Kidney Disease Patients with Sarcopenia: An Overview

“…The PROT-AGE Study Group recommends a protein intake of 0.8 g/kg/day and >0.8 g/kg/day for the elderly CKD patients with GFR < 30 mL/min and 30 to 60 mL/min, respectively [39]. However, in the case of muscle wasting such as sarcopenia, sufficient energy (30 kcal/kg/day) and protein (0.8-1.0 g/kg/day) are recommended for nutritional needs [4]. Some CKD patients with sarcopenia are at high risk for CKD progression to end-stage renal failure, while others have worsening sarcopenia and are at high risk of shortened life expectancy.…”

“…Decreased protein and energy intake due to dietary restriction or anorexia, increased protein catabolism due to activation of renin-angiotensin system or hyperparathyroidism, decreased anabolism due to insulin resistance, chronic inflammation, metabolic acidosis, and hormonal imbalances have been reported to be associated with PEW [2] as well as sarcopenia [3] (Figure 1). These two concepts share the same criteria and have similar causes and outcomes, but they are defined differently [4]. PEW focuses on protein and energy loss associated with inflammation, whereas sarcopenia focuses on muscle mass and strength loss associated with aging.…”