The relationship between plasma leptin and nutritional status in chronic hemodialysis patients

Study of Serum Levels of Leptin, C-Reactive Protein and Nutritional Status in Hemodialysis Patients

Background:

Leptin is secreted by adipose tissue and decreases appetite. However, the role of leptin in the pathogenesis of hemodialysis (HD)-related malnutrition has not been fully evaluated.

Objectives:

The aim of study was to investigate the association between the serum leptin levels, serum C-reactive protein (CRP) levels, and nutritional status in hemodialysis patients.

Patients and Methods:

This analytical descriptive study included 45 hemodialysis patients and 40 healthy subjects. Biochemical parameters and serum leptin levels were measured. The nutritional status was evaluated using a food frequency questionnaire (FFQ) and the calculation of the body mass index (BMI).

Results:

Serum leptin (P < 0.05) and albumin (P < 0.0001) levels and BMI (P < 0.001) of HD patients were significantly lower, while CRP levels were significantly higher than those of controls (P < 0.0001). HD patients consumed the lower daily servings of the food groups compared to the control subjects (P < 0.0001). A significant positive correlation between serum levels of leptin and albumin and BMI was demonstrated. No significant correlations were identified between leptin level, CRP level, and other variables.

Conclusions:

The findings suggest that low levels of leptin may be a contributory factor for malnutrition in HD patients. Further studies are required to ascertain the significance of leptin levels in relation to nutritional factors in hemodialysis patients.

Relationship between serum leptin level and laboratory and anthropometric indices of malnutrition in patients on hemodialysis

Protein-energy malnutrition is a major problem and one of the risk factors for mortality in hemodialysis patients. There is no single index in evaluation of nutritional status in these patients, so leptin can be used as one of the parameters. In this study, the correlation between serum leptin with biochemical and anthropometric parameters of nutrition has been evaluated. This cross-sectional study has been performed on 60 hemodialysis patients (32 males and 28 females) in 2006. The patients on hemodialysis for under 1 year and who has a history of consumption of lipid lowering agents or glucocorticoids, or an infectious or inflammatory disease were excluded. Malnutrition laboratory parameters and serum leptin were measured before hemodialysis. Serum leptin was measured with enzyme-linked immunosorbent assay (ELISA) method with direct dbc kit and malnutrition laboratory parameters measured with standard laboratory methods, patients anthropometric parameters evaluated after hemodialysis. The mean age of patients was 47.5 ± 16.1 years and the range of serum leptin level was 0.6-64.8 ng/ml. Mean serum leptin level were 22.64 ± 19.54 ng/ml in females and 16.74 ± 20.16 ng/ml in males on hemodialysis and in spite of higher level of leptin in females there was not any statistically significant difference between females and males serum leptin. Absolute value of correlation coefficient between serum leptin and anthropometric parameters and most laboratory parameters was < 0.25 (except ferritin, iron, phosphorous in males and total protein, hemoglobin, urea, and creatinin in females which was between 0.25 and 0.50). Our results suggest that the increased serum leptin level does not have a major role in diagnosis of malnutrition in hemodialysis patients and there is a poor correlation between malnutrition parameters and serum leptin level.

Adipocytokines leptin and adiponectin, and measures of malnutrition-inflammation in chronic renal failure: is there a relationship?

BACKGROUND

Serum levels of adipocytokines such as leptin and adiponectin are significantly elevated in patients with chronic renal failure (CRF). The effect of such adipocytokines on malnutrition in the CRF population has been of substantial interest. We sought to determine the relationship between plasma leptin and adiponectin levels and malnutrition-inflammation status in end-stage renal disease patients.

METHODS

Thirty patients (15 women and 15 men; mean [+/-SD] age, 50 +/- 14 years) on hemodialysis, and 30 patients (12 women and 18 men; mean [+/-SD] age, 47 +/- 16) on continuous ambulatory peritoneal dialysis, were enrolled in this study. Adipocytokine levels were measured by enzyme-linked immunosorbent assay. Inflammatory markers, such as high-sensitivity serum C-reactive protein (hs-CRP), ferritin, and a nutritional inflammatory scoring system known as the malnutrition-inflammation score (MIS), were also measured in all patients.

RESULTS

Serum leptin had negative correlations with ferritin (r = -0.33, P = .016) and MIS (r = -0.39, P = .003). Adiponectin had a weak positive correlation with MIS (r = 0.26, P = .050), indicating that an increased level of serum adiponectin was associated with a worse nutritional status. Levels of hs-CRP, serum albumin, cholesterol, and triglycerides did not correlate with nutritional status.

CONCLUSIONS

Serum leptin concentration seems to be a marker of good nutritional status, rather than an appetite-suppressing uremic toxin, in patients with CRF. However, the positive correlation between serum adiponectin and worse nutritional-inflammatory status suggests that elevated adiponectin levels may contribute to the pathogenesis of malnutrition in such patients.

Leptin, ghrelin, and proinflammatory cytokines: compounds with nutritional impact in chronic kidney disease?

Metabolic and nutritional derangements are prominent features of the uremic syndrome. Recent evidence suggest that several large-molecular-weight molecules that often are elevated in uremia, such as leptin, ghrelin, and proinflammatory cytokines, may have nutritional impact in this patient group. On the basis of present knowledge, these compounds could be regarded as suspected but not established uremic toxins. The discovery of the ob gene, its product leptin, and cerebral leptin receptors has undoubtedly widened our understanding of obesity and the underlying molecular and physiologic mechanisms that regulate food intake and body weight. Moreover, the recent discovery of leptin receptor isoforms in several peripheral organs suggests that leptin besides having a central function also has several important peripheral biological functions. Because uremic patients in general have an inappropriate elevation of circulatory leptin, further research is necessary to determine the potential biological effects of elevated leptin levels in end-stage renal disease. Also, because many symptoms and findings prevalent in the uremic syndrome are known to be associated with elevated levels of proinflammatory cytokines, such as interleukin-6, future studies are needed to evaluate the role of specific anti-inflammatory treatment strategies in malnourished uremic patients.