Serum and urinary leptin and ghrelin in children with nephrotic syndrome.

OBJECTIVE: The aim of the present study was to evaluate the serum and urinary levels of leptin and ghrelin in children with primary idiopathic nephrotic syndrome (NS), to compare these results between patients during the relapse and remission phase and to evaluate the possible role of leptin and ghrelin in the pathogenesis of NS.

PATIENTS AND METHODS: Forty-nine children with primary idiopathic NS (25 children with relapse and 24 children in remission), who were followed up at the Pediatric Nephrology Unit, enrolled. Twenty-eight age- and sex-matched healthy children served as controls. Serum and urinary leptin levels were determined by immunoenzymatic ELISA, and serum and urinary ghrelin levels were determined by the RIA method.

RESULTS: The serum leptin levels were significantly lower in the children with NS during the relapse phase than in the children with NS during remission or in the controls (1.42±0.34 ng/dl and 3.60±0.70 ng/ml; p<0.01, 1.42±0.34 ng/ml and 5.27±4.67 ng/ml; p<0.001, respectively). The urinary leptin excretion levels were significantly higher in the relapse group than in the controls (0.40±0.11 ng/ml and 0.12±0.06 ng/ml, p<0.01, respectively). The serum ghrelin levels were similar between the study groups (p>0.05). The urinary ghrelin excretion levels were significantly higher in the relapse group than in the remission group and the controls (965.0 pg/ml [93-3711] and 679.7 pg/ml [93-3783], p<0.05; 965.0 pg/ml [93-3711] and 387.7 pg/ml [114-1214], p<0.001, respectively). The urinary ghrelin levels were also significantly higher in the remission group than in the controls (679.7 pg/ml [93-3783] and 387.7 pg/ml [114-1214]), p<0.01, respectively). The serum leptin levels were positively correlated with the serum albumin levels (r=0.440, p<0.05) and were negatively correlated with the serum triglyceride levels during the relapse phase. The urinary leptin and ghrelin levels were positively correlated with proteinuria in the relapse group.

CONCLUSIONS: We propose that leptin plays a role in the pathophysiology of NS and is associated with proteinuria, hypoproteinemia and hyperlipidemia. The significant urinary excretion of ghrelin in children with NS is possibly due to underlying pathophysiological changes, and normal serum ghrelin levels might be associated with an unknown compensatory mechanism.