Muscle fat infiltration in chronic kidney disease: a marker related to muscle quality, muscle strength and sarcopenia.

Muscle fat infiltration (MFI) also known as myosteatosis refers to any deposit of lipids found in the skeletal muscle. MFI is preferably assessed by image-based methods like computed tomography (CT), magnetic resonance image (MRI) and ultrasound, normally from muscle groups located in the legs, arms and in the trunk. MFI is understood as a marker of muscle quality, where a muscle with higher fat deposition has lower contraction power and capacity to produce force per unit of muscle mass. This concept supports the hypothesis that a decrease in muscle strength is not always explained by a decrease in muscle mass, but also by other factors, including lipid deposition in the muscle. In the general population, MFI is associated with older age, physical inactivity and with insulin resistance and inflammation. In chronic kidney disease (CKD), MFI has been associated with a decrease in muscle strength and impaired muscle quality as well as with metabolic abnormalities, cardiovascular disease and increased mortality. Interventions aimed at reducing MFI in CKD are incipient, but it seems that guided exercise can ameliorate muscle quality in patients on hemodialysis. The aim of this narrative review about MFI in CKD is to draw attention to a still not often addressed complication in CKD. We conclude that more studies are warranted to investigate mechanisms and factors promoting MFI in CKD. Thus, clinical trials aimed at understanding the type, frequency and intensity of exercise that can diminish MFI and improve the clinical condition of the patients are needed.

Effects of supplementation with vegetable sources of alpha-linolenic acid (ALA) on inflammatory markers and lipid profile in individuals with chronic kidney disease: A systematic review and meta-analysis.

BACKGROUND AND AIMS: Inflammation and dyslipidemia are traditional risk factors and well-known causes of morbidity and mortality in chronic kidney disease (CKD). Alpha-linolenic acid (ALA), an essential fatty acid mainly found in vegetable sources, has been associated with anti-inflammatory effects and improving lipid profile. This systematic review and meta-analysis investigate the effects of supplementation with vegetable sources of ALA on inflammatory marker and lipid profile in individuals with CKD. METHODS: This review included studies with adult or elderly patients with CKD, including those receiving dialysis, using oral supplementation or food or combined interventions containing vegetable sources of ALA. All studies were randomized trials and The Cochrane Collaboration's tool was use for assessing risk of bias. RESULTS: 19 studies provided data for meta-analyses. ALA had significant effect on reducing C-reactive protein (CRP) after supplementation (WMD: -1.32; 84.5% CI, -2.35 to -0.29, P = 0.012), on the other hand, had no significant effect on total cholesterol (WMD: -2.85; 90.1% CI, -14.43 to 8.73, P = 0.629), high density lipoprotein (WMD: 1.09; 92.4% CI, -1.82 to 3.99, P = 0.463), low density lipoprotein (WMD: -3.87; 86.7% CI, -12.62 to 4.89, P = 0.387) and triglycerides (WMD: -16.42; 87.7% CI, -47.83 to 14.98, P = 0.305). CONCLUSION: Vegetables sources of ALA showed beneficial effects on reducing inflammatory marker CRP in CKD patients but had no effect on lipid profile. Future well-designed studies are needed to investigate the effectiveness of vegetables sources of ALA, particularly in CKD.

Comparison of Body Mass Index, Skinfold Thickness, and Bioelectrical Impedance Analysis With Dual-Energy X-Ray Absorptiometry in Hemodialysis Patients.

BACKGROUND: Malnutrition is a consistent finding in hemodialysis (HD) patients and is associated with high mortality. The aim was to compare nutrition status indicators using dual-energy x-ray absorptiometry (DXA) as reference in HD patients. METHODS: Observational cross-sectional study with 42 patients, 55.8 years (±14.6) old, 60% male, HD 2-3 times per week for ≥3 months. HD ranged from 3 months to 28 years (median, 17.3; interquartile range, 8.73-39.0). We used body mass index (BMI) and fat mass (FM) by skinfold thickness (SFT), bioelectrical impedance analysis (BIA), and DXA. Statistical analyses used Bland-Altman plots, Lin's concordance correlation coefficient, the paired t-test, and Pearson or Spearman correlation. P < .05 was significant. RESULTS: SFT and DXA presented the lowest prevalence of malnutrition (2.4%) and BMI the highest (28.6%). BMI, BIA FM, and SFT FM presented strong positive correlations with DXA FM (r = 0.915; r = 0.976; r = 0.910, P < .001, respectively). BIA FM and fat-free mass (FFM) demonstrated substantial agreement with DXA values (ρ = 0.974 and 0.960, P < .001). Thus, the measurement procedures used, SFT and BIA, underestimated %FM (-4.65% and -2.13%) and overestimated FFM (3.12 kg and 1.0 kg) according to DXA. No differences were found between mean values of BIA FM and DXA (P = .178). CONCLUSIONS: Compared with DXA, BIA was the most appropriate nutrition indicator for measuring body composition.