Leptinemia and its relation to sex hormones and obesity in patients with chronic renal failure

Background: Chronic renal failure is a predominant reduction in glumerular filtration rate (GFR) sufficient to produce alterations in well-being and organ function. Endocrine abnormalities common in chronic renal insufficiency is the association of higher serum leptin levels in their patients. Leptin is a protein hormone produced mainly by adyposites. Serum leptin concentrations positively correlate with body mass index (BMI) and body fat content. Changes of androgens synthesis and metabolism develop early after the onset of renal insufficiency and are likely to be caused by primary hypogonadism and /or disturbances of the hypothalamic pituitary –axis. Aim: The aim of the present work is to analyze the contribution of serum testosterone and astradiol concentrations with leptinemia in hemodialyzed patents together with waist circumference and BMI. In order to shed some light on the mechanism of biodegradation of leptin by the kidneys in both genders and how it is affected by body composition and weight. Subjects and Methods: A total of 45 subjects were involved in this study, 30 of them had chronic renal failure and the remaining 15 subjects were normal healthy individuals served as a control. Five mls of blood were withdrawn from each subject by vein puncture, patients and control. ELISA technique was used for the measurement of serum leptin level while RIA technique was used for the measurements of testosterone and estradiol levels. Data were expressed as mean±SD. results were evaluated using the student t-test for paired data. Conventional methods were used for the correlation and regression analyses. Results: Results obtained showed that the level of serum leptin and serum estradiol in patients with chronic renal failure were significantly higher than that in healthy subjects, whereas testosterone level was significantly lower in patients than in healthy subjects.The anthropometrical measurement in patients with chronic renal failure had significantly higher values of waist but significant lower values of BMI. Male with chronic renal failure showed a significant lower level of serum leptin concentration than in females. However the anthropometrical measurements (BMI & waist) of males were significantly higher than those in the females. Serum leptin level was positively correlated with serum estradiol whereas it had an inverse correlation with testosterone. Leptin had positive correlation with each of the studied anthropometrical measurements (BMI & waist). All results are thoroughly discussed in the text. Kufa Med.Journal 2009.VOL.12.No2. 150 Conclusion : Increased levels of serum leptin and estradiol in CRF patients is a reflection of the increased waist circumference and the poor ability of the kidney for biodegradation of both these hormones. On the other hand testosterone had a significant effect on serum leptin levels as can be shown through its positive effect in males rather than in females. Introduction Chronic renal failure is a predominant reduction in glumerular filtration rate (GFR) sufficient to produce alterations in well-being and organ function. It represents an evolutionary process that is initiated by various causes, all with the common results of persistent and usually progressive damage of varying severity to the kidneys. Patients with renal insufficiency show from the onset of their disease, a pattern of hormonal changes resulting from complex disturbances at the hypothalamic, pituitary and gonadal level. This endocrine dysfunction can only partially be influenced by renal replacement therapy such as hemodialysis or kidney transplantation. Impaired function of the hypothalamic, pituitary and gonadal axis is not reversed by initiation of otherwise effective hemodialysis therapy. Other endocrine abnormalities common in chronic renal insufficiency is the association of higher serum leptin levels in their patients. Leptin is a protein hormone produced mainly by adyposites. Serum leptin concentrations positively correlate with body mass index (BMI) and body fat content. Malnourished patients or lean individuals have decreased leptin levels proportional to the less of body fat. Increased levels of leptin in patients with chronic renal failure can be explained to lower clearance of leptin by the kidney and increased insulin and proinflammatory cytokine stimulation of leptin synthesis. Changes of androgens synthesis and metabolism develop early after the onset of renal insufficiency and are likely to be caused by primary hypogonadism and /or disturbances of the hypothalamic pituitary –axis. The aim of the present work is to analyze the contribution of serum testosterone and astradiol concentrations with leptinemia in hemodialyzed patents together with waist circumference and BMI, in order to shed some light on the mechanism of biodegradation of leptin by the kidneys in both genders and how it is affected by body composition and weight. Subjects and methods A total of 45 subjects were involved in this study, 30 of them had chronic renal failure and the remaining 15 subjects were normal healthy individuals served as a control. Age range of the patients was between 25 and 45 years with a mean of 37±8.2 years and a mean BMI of 24.3±3.3 kg/m. Sixteen of the patients were females with a mean BMI of 22.6±3.1 kg/m. The remaining 14 patients were males with a mean BMI 25.3 ±2.2kg/m. The age range of the control subjects was also between 25-45 years with a mean of 30±10.3 years, with normal weights and a mean BMI of 29.0±4.7 kg/m. Five mls of blood were withdrawn from each subject by vein puncture, patients and control. The blood was then transferred into plastic tubes, left for 2 hours before centrifugating them at 500rpm for 10 minutes to get as much serum as possible. Enzyme linked immuno assay (ELISA) was used for the measurement of serum leptin level. Radio immuno assay (RIA) technique was used for the measurements of testosterone and estradiol levels. Kufa Med.Journal 2009.VOL.12.No2. 151 The radio immune assay kits for the measurements of the mentioned parameters were obtained from DIOsorin, still waster, Minnesota USA. Data were expressed as mean±SD. Results were evaluated using the student t-test for paired data. Conventional methods were used for the correlation and regression analyses. Results Mean (±SD) of the studied hormones (serum leptin, testosterone and estradiol) and the anthropometrical measurement (BMI and waist circumference) are shown in table (1). Table 1 : Mean (±SD) of the studied hormones (serum leptin, testosterone and estradiol) and the anthropometrical measurement (BMI and waist circumference) CRF patients Healthy subjects parameters 30 15 No. investigated 24.3 ± 3.3** 29.0 ± 4.7 BMI kg/ m2 60.7 ± 3.4** 55.2 ± 3.5 Waist circumference cm 26.6 ± 8.6** 10.4 ± 4.4 Leptin ng/ ml 8.9 ± 9.7** 14.7 ± 13.0 Testosterone 230 ± 19.6** 134 ± 137 Estradiol