Leptin is a Negative Acute-Phase Protein in Chronic Hemodialysis Patients

Leptin is a hormone secreted by adipocytes that regulates thermogenesis, appetite, and body fat. This hormone is a product of the ob gene and is a single-chain 16-kDa protein that is expressed almost exclusively in human adipose tissue. Furthermore, leptin has actions in the immune system, bone formation, and angiogenesis. Previous data indicated that high serum leptin is a component of the metabolic syndrome and a risk factor for cardiovascular disease in the general population and patients with normal kidney function. In patients with normal glomerular filtration rate (GFR), there is net renal uptake of 12% of circulating leptin, whereas in renal insufficiency there is no renal uptake of leptin. Plasma leptin is not cleared by hemodialysis with a modified cellulose membrane. It seems that kidney failure is an important factor affecting blood leptin levels, especially in obese patients. Hyperleptinemia was closely related to fat mass in patients on chronic hemodialysis. Carrero and coworkers demonstrated that patients with protein energy wasting and low plasma ghrelin had high leptin and high C-reactive protein levels, and higher mortality rate compared to the control group. On the other hand, Nasri and Baradaran reported that in patients on hemodialysis, the association of leptin with C-reactive protein levels was inversed which could show the positive effects of leptin on nutrition and support the theory of protective effects of leptin in hemodialysis patients.