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Bone and muscle tissue are developed hand-in-hand during childhood and adolescence and interact through mechanical loads and biochemical pathways forming the musculoskeletal system. Chronic kidney disease (CKD) is widely considered as both a bone and muscle-weakening disease, eventually leading to frailty phenotype, with detrimental effects on overall morbidity. CKD also interferes in the biomechanical communication between two tissues. Pathogenetic mechanisms including systemic inflammation, anorexia, physical inactivity, vitamin D deficiency and secondary hyperparathyroidism, metabolic acidosis, impaired growth hormone/insulin growth factor 1 axis, insulin resistance, and activation of renin-angiotensin system are incriminated for longitudinal uncoordinated loss of bone mineral content, bone strength, muscle mass, and muscle strength, leading to mechanical impairment of the functional muscle-bone unit. At the same time, CKD may also interfere in the biochemical crosstalk between the two organs, through inhibiting or stimulating the expression of certain osteokines and myokines. This review focuses on presenting current knowledge, according to in vitro, in vivo, and clinical studies, concerning the pathogenetic pathways involved in the muscle-bone axis, and suggests approaches aimed at preventing bone loss and muscle wasting in the pediatric population. Novel therapeutic targets for preserving musculoskeletal health in the context of CKD are also discussed. [ABSTRACT FROM AUTHOR]

Objective: To investigate the ability of phase angle (PA) and body composition for predicting protein energy wasting (PEW) in renal replacement therapy (RRT) patients. Methods: Renal replacement therapy (RRT) patients were enrolled in this study. Body composition was measured by direct segmental multi‐frequency biolectrical impedance analysis method (DSM‐BIA); phase angle (PA), fat‐free mass (FFM), fat mass (FM), mid‐arm circumference (MAC), WC (waist circumference), and ECW/TBW (extracellular water/total body water) were obtained. Biochemicals (serum albumin, triglyceride, and cholesterol) were tested. PEW patients were classified according to ISRNM (The International Society of Renal Nutrition and Metabolism) criteria. Cutoff value of PA and related variables was calculated by ROC analysis. The ability of body composition variables as indicators to predict PEW was evaluated. Results: Sixty‐four patients were enrolled in this study. Thirty‐three patients (52.6%) were males, and forty (62.5%) patients were diagnosed with PEW. The ROC curve showed that the optimal cutoff values of PA, FFMI (fat‐free mass index), MAC, WC, and BMI for PEW risk were 4.45°, 16.71, 29.7 cm, 86.4 cm, and 21.1 kg/m2, respectively. These indicators showed significant association with PEW; meanwhile, the PA and MAC can be used as the predictors for PEW with OR 6.333 (95% CI, 1.956–20.505) and 3.267 (95% CI, 1.136–9.394), respectively. Both groups have a lower BUN/Cr ratio (<20). Conclusion: In the RRT patients, over than 60% patients were diagnosed with PEW. PA, MAC, and other body composition can be used as the independent indicators for predicting PEW in renal replacement therapy kidney disease patients. [ABSTRACT FROM AUTHOR]

Some children with declining height and BMI SDS fail to respond to optimisation of nutritional intake. As well as poor growth, they have muscle wasting and relative preservation of body fat. This is termed protein energy wasting (PEW). The process results from an interaction of chronic inflammation alongside poor nutritional intake. This review discusses the causes and potential preventative therapies for PEW. [ABSTRACT FROM AUTHOR]

The importance of kidney damage in obese patients is due to the increasing incidence of nephropathies associated with metabolic disorders, their predisposition to a progressive course of the disease, and the need to optimize early disease detection. The purpose of our work is to study the level of cystatin C, ghrelin, and their interrelation in patients with early stages (I-II) of chronic kidney disease (CKD) against the background of obesity. The indicators of daily microalbuminuria in patients of both groups were studied, and it was found that in patients with stage 2 CKD with obesity, it was 1.2 times higher than in patients with stage 1 CKD with obesity. Patients of the second group revealed a direct middle correlation between daily albuminuria and body mass index (BMI), which indicates deterioration in the functional state of the kidneys against the background of obesity. We obtained an increase in the serum concentration of cystatin C in stage 2 CKD with obesity, reflecting the state of glomerular filtration and the degree of renal function decrease. Correlation analysis showed a positive relation of cystatin C with increased urinary albumin excretion in both groups, plasma creatinine content, BMI, and age. Simultaneously with the increase in the level of cystatin C and the decrease in the glomerular filtration rate, there was an increase in ghrelin levels in stage 2 CKD and the progression of obesity, while such dependence was not seen in stage 1 CKD. [ABSTRACT FROM AUTHOR]

Dietary management in pediatric chronic kidney disease (CKD) is an area fraught with uncertainties and wide variations in practice. Even in tertiary pediatric nephrology centers, expert dietetic input is often lacking. The Pediatric Renal Nutrition Taskforce (PRNT), an international team of pediatric renal dietitians and pediatric nephrologists, was established to develop clinical practice recommendations (CPRs) to address these challenges and to serve as a resource for nutritional care. We present CPRs for energy and protein requirements for children with CKD stages 2–5 and those on dialysis (CKD2–5D). We address energy requirements in the context of poor growth, obesity, and different levels of physical activity, together with the additional protein needs to compensate for dialysate losses. We describe how to achieve the dietary prescription for energy and protein using breastmilk, formulas, food, and dietary supplements, which can be incorporated into everyday practice. Statements with a low grade of evidence, or based on opinion, must be considered and adapted for the individual patient by the treating physician and dietitian according to their clinical judgment. Research recommendations have been suggested. The CPRs will be regularly audited and updated by the PRNT. [ABSTRACT FROM AUTHOR]

Background: This study aimed to evaluate plasma concentrations of leptin and total ghrelin in children with chronic kidney disease (CKD) and assess their roles in protein-energy wasting (PEW).Methods: This study consisted of three different CKD populations [CKD group (20 patients with non-dialysis CKD), dialysis group (39 patients on dialysis), and kidney transplant (KTx) group (35 KTx recipients)] and control group (18 healthy children). Plasma leptin and total ghrelin levels were measured. Multi-frequency bioimpedance analysis was used for the assessment of fat and lean mass. PEW was defined using criteria including body mass, muscle mass, growth, serum albumin level, and protein intake.Results: While plasma leptin levels did not differ among the study groups, total ghrelin levels were significantly higher in the dialysis group (P < 0.001). Seven dialysis patients (18%) and one CKD patient (5%) but none of the KTx recipients met the criteria of PEW. Dialysis patients with PEW had lower plasma leptin levels compared to their counterparts (P = 0.018); however, total ghrelin levels did not differ between the two groups (P = 0.10). Low leptin level in dialysis patients was independently associated with lower fat mass index (P < 0.001) and lower height-specific SD scores of BMI (P = 0.019).Conclusions: PEW is prevalent in dialysis patients. Low levels of leptin seem to be associated with PEW. Our result suggests that low leptin levels may be a consequence rather than a cause of PEW. Longitudinal studies are required to investigate this complex relationship between leptin and PEW in pediatric dialysis patients. [ABSTRACT FROM AUTHOR]

Background: Impairment in orexigenic/anorexigenic hormone balance may be key in the pathogenesis of protein energy wasting in children with chronic kidney disease (CKD). Measurement of ghrelin and obestatin concentrations in children with CKD would help assess the potential contribution of these hormones to uremic protein energy wasting.Methods: This was a cross-sectional case-control study. Acylated and unacylated ghrelin and obestatin were measured in 42 children on conservative treatment (CT), 20 children on hemodialysis, 48 pediatric renal transplant (RTx) recipients and 43 controls (CTR) (mean age 11.9, range 5-20 years). Weight, height and bicipital, tricipital, subscapular and suprailiac folds were measured, and the body mass index-standard deviation score (BMI-SDS), percentage of fat mass and fat-free mass were calculated. Urea and creatinine were measured and the glomerular filtration rate (GFR) calculated.Results: Unacylated ghrelin level was higher in patients than controls (p = 0.0001), with the highest levels found in hemodialysis patients (p = 0.001 vs. CKD-CT, p = 0.0001 vs. RTx, p < 0.0001 vs. CTR). Obestatin level was significantly higher in patients on hemodialysis than those on conservative treatment, RTx recipients and controls (p < 0.0001 in each case). Unacylated ghrelin negatively correlated with weight-SDS (p < 0.0001), BMI-SDS (p = 0.0005) and percentage fat mass (p = 0.004) and positively correlated with percentage fat-free mass (p = 0.004). Obestatin concentration negatively correlated with weight-SDS (p = 0.007). Unacylated ghrelin and obestatin concentrations positively correlated with creatinine and urea and inversely with eGFR, even after adjustments for gender, age, puberty and BMI-SDS (p < 0.0001 for each model).Conclusions: Unacylated ghrelin and obestatin, negatively related to renal function, seem to be promising inverse indicators of nutritional status in children with CKD. Potential therapeutic implications in terms of optimization of their removal in patients on hemodialysis could be hypothesized. [ABSTRACT FROM AUTHOR]