Endocrine Role of Stomach in Appetite Regulation in Chronic Kidney Disease: About Ghrelin and Obestatin

Serum leptin level is associated with phase angle in CKD5 patients not undergoing dialysis

Objective

Malnutrition is very complex in patients with end-stage renal disease (ESRD) and is associated with poor prognosis. This is because hemodynamic changes, hormonal changes, persistent inflammatory reactions, and fluid overloads are more complicated as uremia is worsening. Bio-impedance spectroscopy (BIS) is a useful method to estimate fluid balance (Overhydration/ extracellular water, OH/ECW) and nutritional status (Phase angle, PhA). We aimed to evaluate the volume and nutritional status by BIS and to investigate the relationship between the appetite regulating hormones and the parameters of BIS in patients with stage 5 chronic kidney disease not undergoing dialysis (CKD5-ND).

Methods

We enrolled a total of 91 CKD5-ND patients. We measured routine serum markers including albumin and NT-proBNP and the appetite regulating hormones, leptin and ghrelin. We defined poor nutritional status as a PhA < 4.5°, and proper nutritional status as a PhA ≥ 4.5°. We also evaluated each patient’s nutritional status by assessing their geriatric nutritional risk index (GNRI) and their volume status by measuring NT-proBNP.

Results

Forty-one patients (45%) had poor nutritional status. Patients with a poor nutritional status had significantly higher OH/ECW (29.6 ± 12.7% vs. 6.2 ± 10.3%, p<0.001) and lower levels of leptin (3.8 ± 3.1 vs. 7.0 ± 6.2 ng/mL, p = 0.004) than those with proper nutritional status. PhA was associated with GNRI (r = 0.597, P<0.001) and NT-proBNP was associated with OH/ECW (r = 0.384, P<0.001). Leptin was negatively correlated with OH/ECW (r = -0.288, p = 0.006). In contrast, leptin was positively correlated with PhA (r = 0.263, p = 0.012). In multivariate logistic regression, high level of leptin (OR 7.00, 95% CI 1.74–28.10) was associated with proper nutrition, while an increased OH/ECW (OR 0.65, 95% CI 0.51–0.84) was associated with poor nutrition.

Conclusions

Our study demonstrates that CKD5-ND patients with poor nutrition generally also suffer from excessive body fluid. Low leptin level suggests poor nutrition in CKD5-ND patients. PhA could be used as a nutritional index for ESRD patients.

Age modifies the association between serum obestatin, appetite and nutritional status in maintenance hemodialysis patients

BACKGROUND/OBJECTIVES

Increased age is strongly associated with anorexia and protein-energy wasting (PEW) in maintenance hemodialysis (MHD) population. We hypothesized that the association of obestatin, a recently discovered anorexigenic gut hormone, with appetite and nutritional status differs by age groups.

SUBJECTS/METHODS

We performed a cross-sectional study on 261MHD patients. Obestatin, acyl-ghrelin, markers of inflammation (CRP, IL-6, TNF-α) and nutrition (self-reported appetite, dietary intake, biochemical nutritional parameters, and body composition) were measured.

RESULTS

Obestatin was associated with appetite in multivariate analyses even after controlling for such confounders as lean body mass (LBM), IL-6 and acyl-ghrelin in patients younger than 71 years. For each ng/ml increase in obestatin levels, the odds for diminished appetite was 0.75 (95% CI: 0.59-0.96). However, these associations were not observed in patients 71 years and older. Multivariable logistic regression models (including appetite) also showed increasing odds for PEW (defined by ESPEN consensus-based criteria for the diagnosis of malnutrition) across increasing serum obestatin levels (OR: 1.51, 95% CI: 1.05-2.18) in patients 71 years and older. However, after lean body mass (LBM) was added to this model, the association between obestatin and malnutrition was abolished (OR: 1.26, 95% CI: 0.83-1.91).

CONCLUSIONS

The association between serum obestatin, appetite and PEW differs depending on age in MHD patients. A positive link with appetite exists in patients younger than 71 years, whereas this relationship disappears by the age of 71. In older MHD patients, obestatin is associated with PEW through mechanisms related to LBM, but not to appetite.

The expanding roles of the ghrelin-gene derived peptide obestatin in health and disease

Obestatin is a 23 amino acid, ghrelin gene-derived peptide hormone produced in the stomach and a range of other tissues throughout the body. While it was initially reported that obestatin opposed the actions of ghrelin with regards to appetite and food intake, it is now clear that obestatin is not an endogenous ghrelin antagonist, but it is a multi-functional peptide hormone in its own right. In this review we will discuss the controversies associated with the discovery of obestatin and explore emerging central and peripheral roles of obestatin, which includes adipogenesis, pancreatic homeostasis and cancer.