Fasting serum leptin level correlates with mid-arm fat area in peritoneal dialysis patients

Nutrition in Peritoneal Dialysis

The use of peritoneal dialysis (PD) has been associated with improved quality of life, cost-effectiveness, and better outcomes for patients with kidney failure. However, many patients utilizing PD for replacement therapy face numerous nutritional hurdles. As the use of PD continues to increase worldwide, malnutrition has become an increasingly recognized concern for patients undergoing PD. The nephrology community needs to recognize and treat malnutrition to promote optimal nutritional states for our patients. In this review, we discuss several factors that contribute to malnutrition and protein-energy wasting and explore the benefits and limitations of nutritional parameters used to assess protein-calorie malnutrition. We also emphasize updated guidelines on daily caloric, protein, and micronutrient recommendations, as well as their effects on electrolyte homeostasis.

Vascular endothelial growth factor-mediated peritoneal neoangiogenesis in peritoneal dialysis

Peritoneal dialysis (PD) is an important renal replacement therapy for patients with end-stage renal diseases, which is limited by peritoneal neoangiogenesis leading to ultrafiltration failure (UFF). Vascular endothelial growth factor (VEGF) and its receptors are key angiogenic factors involved in almost every step of peritoneal neoangiogenesis. Impaired mesothelial cells are the major sources of VEGF in the peritoneum. The expression of VEGF will be up-regulated in specific pathological conditions in PD patients, such as with non-biocompatible peritoneal dialysate, uremia and inflammation, and so on. Other working cells (i.e. vascular endothelial cells, macrophages and adipocytes) can also stimulate the secretion of VEGF. Meanwhile, hypoxia and activation of complement system further aggravate peritoneal injury and contribute to neoangiogenesis. There are several signalling pathways participating in VEGF-mediated peritoneal neoangiogenesis including tumour growth factor-β, Wnt/β-catenin, Notch and interleukin-6/signal transducer and activator of transcription 3. Moreover, VEGF is highly expressed in dialysate effluent of long-term PD patients and is associated with peritoneal transport function, which supports its role in the alteration of peritoneal structure and function. In this review, we systematically summarize the angiogenic effect of VEGF and evaluate it as a potential target for the prevention of peritoneal neoangiogenesis and UFF. Preservation of the peritoneal membrane using targeted therapy of VEGF-mediated peritoneal neoangiogenesis may increase the longevity of the PD modality for those who require life-long dialysis.

Angiogenesis and Inflammation in Peritoneal Dialysis: The Role of Adipocytes

Chronic inflammation and angiogenesis are the most common complications in patients undergoing maintenance peritoneal dialysis (PD), resulting in progressive peritoneum remolding and, eventually, utrafiltration failure. Contributing to the deeper tissue under the peritoneal membrane, adipocytes play a neglected role in this process. Some adipokines act as inflammatory and angiogenic promoters, while others have the opposite effects. Adipokines, together with inflammatory factors and other cytokines, modulate inflammation and neovascularization in a coordinated fashion. This review will also emphasize cellular regulators and their crosstalk in long-term PD. Understanding the molecular mechanism, targeting changes in adipocytes and regulating adipokine secretion will help extend therapeutic methods for preventing inflammation and angiogenesis in PD.

The association of serum leptin levels with metabolic diseases

Leptin is a 167-amino-acid protein released by white adipose tissue and encoded by the obese gene. It has a role as a negative regulator of appetite control through sending a satiety signal to act on receptors within the hypothalamus. At normal levels, leptin can exert its effects on weight regulation according to white fat mass, induce sodium excretion, maintain vascular tone, and repair the myocardium. Beyond these effects, elevated serum leptin levels have been implicated in the pathogenesis of metabolic syndrome, diabetes mellitus, hypertension, and multiple cardiovascular diseases. In addition, hyperleptinemia had been reported to contribute to renal diseases through multiple mechanisms resulting in glomerulopathy presenting with a decreased glomerular filtration rate, increased albuminuria, and related clinical symptoms, which are pathophysiological features of chronic kidney disease. Because these cardiovascular and metabolic disorders are great challenges for physicians, understanding the related pathophysiological association with leptin might become a valuable aid in handling patients in daily clinical practice. This review will discuss the roles of leptin in the regulation of biological functions of multiple organs beyond the maintenance of feeding and metabolism.

Triceps Skinfold Thickness Is Associated With Lumbar Bone Mineral Density in Peritoneal Dialysis Patients

Anthropometric measurements, including body mass index (BMI), body weight and total fat mass are associated with the bone mineral density (BMD) in the general population. Compared to that in the general population, BMD was lower in dialysis patients. However, the association between anthropometric measurements and BMD is not well-established among peritoneal dialysis (PD) patients. To study this, we conducted a cross-sectional study in 48 chronic PD patients. Anthropometric parameters, biochemical data, and BMD measured by dual energy X-ray absorptiometry in lumbar vertebrae (L2-L4) were collected. Among these PD patients, eight patients (16.7%) had osteoporosis and 22 patients (45.8%) osteopenia, while 18 patients were normal. Older age, decreased height, lower body weight, BMI, triceps skinfold thickness (TSF), mid-arm fat area (MAFA), and higher adiponectin levels were observed in our patients with lower lumbar T-scores. Height, body weight, waist circumference, BMI, body fat mass, TSF, mid-arm circumference, MAFA, and serum phosphorus levels were positively, while age, adiponectin levels were negatively correlated with lumbar BMD levels. According to our multivariate forward stepwise linear regression analysis, TSF (R² change = 0.080, P = 0.017) and body weight (R² change = 0.333, P = 0.002) were both correlated with low lumbar BMD. In conclusion, either TSF or body weight in our chronic PD patients was proved to be an independent predictor for osteolytic bone lesions.

Association between serum leptin levels and peritoneal dialysis: A meta-analysis

There is limited information available with regard to the association between serum leptin levels, or other adipokines, and serum lipid levels and insulin sensitivity in patients undergoing peritoneal dialysis (PD). Thus, the aim of the present study was to perform a meta-analysis investigating this association. Potential relevant studies were identified through searching the following databases: MEDLINE, Science Citation Index, Cochrane Library, PubMed, Embase, CINAHL, Chinese Biomedical, Chinese Journal Full-Text and Weipu Journal. Statistical analyses were calculated using version 12.0 STATA software. In total, 21 case-control studies comprising 1,187 subjects (574 patients and 613 controls) were collected for the meta-analysis. The results identified a statistically significant difference in the serum levels of leptin when comparing the PD patients with the healthy controls [controls vs. cases, standardized mean difference (SMD), 2.09; 95% confidence interval (CI), 1.58-2.59; P<0.001]. Furthermore, ethnicity-subgroup analysis indicated that the PD patients of Asian and Caucasian populations were associated with increased serum levels of leptin (Asian population, SMD, 2.05; 95% CI, 1.48-2.62; P<0.001; Caucasian population, SMD, 2.19; 95% CI, 1.19-3.18; P<0.001). Therefore, serum leptin levels may be used as a prognostic marker for PD.

Peritonitis incidence was correlated with duration of peritoneal dialysis rather than leptin or neutrophil to lymphocyte (n/l) ratio in peritoneal dialysis patients

OBJECTIVE

End stage renal disease (ESRD) has a high worldwide prevalence and incidence. Peritonitis is one of the leading causes of hospitalization in peritoneal dialysis patients. Although inflammatory markers show increased inflammatory responses, cellular immune response was decreased in ESRD patients. Leptin is an adipocyte-derived hormone that has activity in energy, nutrition and immune system. Neutrophil to lymphocyte ratio (N/L) was emerged as a predictive and prognostic criterion in many instances. In this study, we aimed to investigate the relationships between increased inflammation in peritoneal dialysis patients and leptin, N/L ratio.

MATERIALS AND METHODS

Forty-one ESRD patients, who were been at least 12 months of peritoneal dialysis therapy, were included in the study. Patients' demographic properties were recorded. Serum leptin level, WBC count, C-reactive protein, erythrocyte sedimentation rate and biochemical markers were measured. Patients with active viral or bacterial infection, malignancy, inflammatory disease, immunosuppressive medication users were all excluded from the study. Age and sex-matched healthy control group was included in the study only for their leptin levels.

RESULTS

The measured mean serum leptin level of the patient group was statistically significantly higher than control group (1624.88±1608.16 and 416±439.85). The calculated mean peritonitis incidence was 0.041±0.047 peritonitis/per year. The number of peritonitis attack was significantly correlated with duration of peritoneal dialysis, body mass index (BMI), age and presence of cardiovascular disease. Serum leptin level was significantly correlated with sex, age, primary cause of ESRD, BMI, blood glucose level and duration of peritoneal dialysis (PD).

CONCLUSION

We detected that ESRD patients have higher serum leptin levels compare to healthy adults. Increased leptin was correlated with sex, age, BMI, primary cause of ESRD and serum glucose level. Number of peritonitis attack and peritonitis incidence was significantly correlated with the duration of PD, BMI and sex. We weren't able to show the predictive N/L value in PD patients in case of peritonitis.

Nutrition and the kidney: recommendations for peritoneal dialysis

Protein energy wasting (PEW) is highly prevalent in peritoneal dialysis (PD) and is associated with poor outcomes, including hospitalization and mortality. Recognizing and diagnosing PEW in PD is important; although studies are limited, there are interventions that may be associated with improved outcomes. In this review of nutritional aspects of PD, we highlight some of the important causes of PEW and explore the current diagnostic tools that are used to assess PEW. Finally, we discuss the established and experimental therapies for PEW in PD.