Renal loss of leptin in patients with nephrotic syndrome

Abstract

Objective: In humans, short term changes of serum leptin lead to alterations in food intake and energy expenditure. The objective of the present study was to relate urine leptin concentrations with the extent of proteinuria in patients with nephrotic syndrome (NS). A second goal was to investigate the impact of potential urinary leptin losses on serum leptin concentrations and body composition. Design and Methods: Seventeen patients with proteinuria were compared with twenty patients with remission of NS and ten healthy children. Leptin was measured by radioimmunoassay. Results: Urinary leptin excretion in proteinuric patients was signi®cantly higher than in nonproteinuric patients with and without NS and in healthy controls 2X64^0X034 mgag creatinine, 0X026^0X05 mgag creatinine, and 0X073^0X11 mgag creatinine respectively; P , 0X001 and P , 0X01 respectively compared with controls). Urine leptin positively correlated with urine IgG concentration P 0X013Y r 2 0X36 in the proteinuric group. No difference in serum leptin values could be demonstrated between the three groups. Conclusions: In summary, our data demonstrate a signi®cant leptin excretion in children with severe proteinuria. Proteinuria, however, does not lead to changes in serum leptin, suggesting that the signi®cant loss of leptin is compensated for by sustained up-regulation of leptin production.

Leptin, soluble leptin receptor, and transforming growth factor-?1 levels in minimal change nephrotic syndrome

“…Some studies showed that leptin production is dependent on adiposity regardless of receptor functioning, and that the leptin receptor by itself may not be specifically involved in the control of leptin secretion [3,4]. In our study, significant positive correlations were observed between serum leptin levels and BMI in all groups, supporting previous studies [9,10]. As there was no signifi- cant difference in BMI among the three groups, the differences in serum leptin levels in the three groups were unlikely to be related to different BMI values.…”

“…Schroth et al [9] demonstrated a significant leptin excretion in children with severe proteinuria. Their results revealed that the glomerular loss of a 16-kilodalton peptide, leptin, was independent of molecular size in patients with proteinuria.…”

Serum and urine leptin concentration in children with nephrotic syndrome

“…The kidneys play a key role in the systemic elimination of circulating leptin [23,25]. Leptin is not metabolized by the kidney but is excreted as an intact protein.…”

“…Leptin is not metabolized by the kidney but is excreted as an intact protein. The mechanism involved is a high capacity non-saturable process, most probably glomerular filtration [22,23]. Leptin concentrations are increased in the plasma of patients with end-stage renal disease and chronic renal failure [27].…”

“…In obese patients the amount of free fatty acids delivered to the liver is increased, upregulating the synthesis and secretion of VLDL apo B [21]. Information concerning serum leptin levels in nephrotic syndrome patients is equivocal [22,23]; we undertook the present study to find out whether children with steroid sensitive nephrotic syndrome (SSNS) have proportionate changes in serum and urine leptin levels to known disturbances in lipid metabolism.…”