Adiponectin, leptin and thyroid hormones in patients with chronic renal failure and on renal replacement therapy: are they related?

Relationship of Thyroid Function with Renal Hemodynamics and Cholesterol Metabolism in Proteinuric Kidney Disease: A Pilot Study

Nephrotic syndrome and hypothyroidism are respectively reported to influence renal hemodynamics and hypercholesterolemia. However, the relationship of proteinuria-associated thyroid function with renal hemodynamics and cholesterol metabolism has yet to be determined in a simultaneous analysis of thyroid, renal, and cholesterol variables. We investigated the hypothesis that the changes in thyroid hormones by proteinuria may contribute to changes in cholesterol metabolism and renal hemodynamics by proteinuria. Twenty-nine patients (17 men and 12 women) with proteinuric kidney disease (mean age 46 years) were enrolled in a pilot study. Data for serum free triiodothyronine (FT3), free thyroxine (FT4), total cholesterol, and filtration fraction (FF; assessed by para-aminohippuric acid clearance) were used in variable-adjusted correlation analyses. The patients had the following data (mean ± standard deviation): urinary protein 5.18 ± 3.28 g/day, FT3 2.18 ± 0.44 pg/mL, FT4 1.03 ± 0.26 ng/dL, FF 0.27 ± 0.07, and total cholesterol 327 ± 127 mg/dL. There was a significant positive correlation of FT3 with FF (β = 0.58, p = 0.01) and a significant inverse correlation of FT4 with total cholesterol (β = -0.40, p = 0.01). A positive correlation of FT3 with FF and an inverse correlation of FT4 with total cholesterol were demonstrated in patients with proteinuric kidney disease. The proteinuria-associated reduction in serum thyroid hormone levels was correlated with hypercholesterolemia and the reduced glomerular FF. Further studies of these relationships are required.

Evaluation of Interactions Between Thyroid Dysfunction in End-Stage Renal Disease Patients: A Cross-Sectional Study

BACKGROUND

Thyroid hormones have a very crucial role in the regulation of metabolism, synthesis of proteins, development, and influencing functions of various other hormones in the human body. While both kidneys play an essential role in the metabolism of thyroid hormone by conversion of thyroxine (T4) to triiodothyronine (T3). In patients with chronic renal failure, frequent abnormal thyroid functions are observed.

AIMS

To evaluate thyroid function in patients of chronic renal failure and to find out their correlation with the severity of the disease.

METHODS

A total of 192 patients were selected for the study after applying inclusion and exclusion criteria. A thyroid function test was done in all enrolled subjects. Serum estimation of T3, T4, and thyroid stimulating hormone (TSH) was done by the chemiluminescent immunoassay (CLIA) method, urea was estimated by the diacetyl monoxide method (DAM, Method), and serum creatinine by Jaffe's method. The results were evaluated for age, sex, and estimated glomerular filtration rate (eGFR) of the patients in view of thyroid dysfunction.

RESULTS

Of all 192 patients enrolled in the study, 124 (64.58%) were male and 68 (35.41%) were females. The observed male-to-female ratio was 1.93:1.18. The mean age of the study group (mean +/- standard deviation, SD) in males was 42+/-18 and in females 38+/-11 years (p value = 0.258). Significant reductions of serum T3, T4, and elevation of TSH were noted in both sexes. A reduced level of T3 was observed in 38.54% (42 males and 32 females) patients, reduced T4 in 34.37% (42 males and 22 females) patients, and subclinical hypothyroidism (SCH) in 16.7% (12 males and 20 females) patients. Biochemical overt hypothyroidism was noted in 7.29% (six males and eight females) of patients.

CONCLUSION

Chronic renal failure is a condition of thyroid hypofunction. A higher prevalence of SCH and clinical hypothyroidism is reported here in chronic kidney disease (CKD) patients. The severity of thyroid hypofunction increases with a progressive reduction in eGFR. Hypothyroidism in CKD patients may be due to different onset mechanisms other than anti-thyroid antibodies.

Leptin, cardiovascular diseases and type 2 diabetes mellitus

Leptin, an adipokine that is implicated in the control of food intake via appetite suppression, may also stimulate oxidative stress, inflammation, thrombosis, arterial stiffness, angiogenesis and atherogenesis. These leptin-induced effects may predispose to the development of cardiovascular diseases. In the present review we discuss the evidence linking leptin levels with the presence, severity and/or prognosis of both coronary artery disease and non-cardiac vascular diseases such as stroke, carotid artery disease, peripheral artery disease (PAD) and abdominal aortic aneurysms (AAA) as well as with chronic kidney disease (CKD) and type 2 diabetes mellitus (T2DM). Leptin levels have been positively associated with the presence, severity, extent and lesion complexity of coronary atherosclerosis as well as with the presence, severity and poor clinical outcomes of both ischemic and hemorrhagic strokes. But conflicting results also exist. Furthermore, leptin was reported to independently predict common carotid intima-media thickness and carotid plaque instability. A link between hyperleptinemia and PAD has been reported, whereas limited data were available on the potential association between leptin and AAA. Elevated leptin concentrations have also been related to CKD incidence and progression as well as with insulin resistance, T2DM, micro- and macrovascular diabetic complications. Statins and antidiabetic drugs (including sitagliptin, metformin, pioglitazone, liraglutide and empagliflozin) may affect leptin levels. Further research is needed to establish the potential use (if any) of leptin as a therapeutic target in these diseases.

Adiponectin, leptin, nitric oxide, and C-reactive protein levels in kidney transplant recipients: comparison with the hemodialysis and chronic renal failure

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of mortality and morbidity in patients with chronic kidney disease (CKD) including kidney transplant recipients (KTR). Secondary lipid metabolism disorders, endothelial dysfunction, and inflammation enhance the risk of CVD development in these patients. The aim of the present study was to investigate the lipid profile, adiponectin, leptin, nitric oxide (NO), and high sensitivity C-reactive protein (hs-CRP) levels in KTR and to compare these parameters with those of the patients with chronic renal failure (CRF), hemodialysis (HD) patients, and healthy controls.

METHODS

Serum adiponectin and leptin levels were measured by radioimmunoassay; hs-CRP was determined immunoturbidimetrically. Determination of NO was based on the Griess reaction.

RESULTS

Compared with the control group, serum NO and adiponectin levels were significantly higher in the KTR, CRF, and HD groups; hs-CRP levels were significantly higher in the KTR and HD groups; leptin levels were significantly higher in the KTR. In addition, serum NO level was significantly higher in the KTR compared to CRF cases. Adiponectin correlated positively with high density lipoprotein-cholesterol in the control and patient groups. A positive correlation was observed between hs-CRP and NO in the KTR and the patients with CRF. Serum adiponectin levels were inversely correlated with hs-CRP and leptin in the HD group.

CONCLUSION

KTR suffer from inflammation and accompanying changes in levels of adipocytokines and NO which contribute to the increased risk of CVD in these patients.

Effect of Transplant on Platelet Function Markers (P-Selectin and Platelet Aggregation) and Adiponectin in Renal Transplant Patients

OBJECTIVES

In chronic kidney disease, both bleeding and thrombotic complications are observed, although with expected recovery after a successful transplant. Adiponectin has protective properties with respect to atherogenesis and inflammation. Plasma adiponectin levels are markedly elevated among patients with end-stage renal disease and are lower after kidney transplant. However, this topic is still debated in the literature. Here, we evaluated the effect of transplant on platelet function markers (P-selectin and platelet aggregation) and adiponectin in renal transplant patients.

MATERIALS AND METHODS

Our study included 14 renal transplant patients. Preoperative and week 1, month 1, month 6, year 1, and year 2 samples after transplant were studied. In addition to plasma adiponectin, P-selectin levels, and platelet aggregation tests, biochemical tests and coagulation parameters were also studied.

RESULTS

We observed a significant decrease in adiponectin levels 2 years after transplant. Platelet function tests with ADP and collagen were significantly improved, and no changes in P-selectin, ristocetin, and epinephrine levels were observed.

CONCLUSIONS

According to our findings, glomerular filtration rate has an important effect on platelet function, but adiponectin levels became normal only in the second year after transplant. Late improvement of low-density lipoprotein cholesterol and adiponectin after transplant suggested to us that patients with kidney transplant may still have risk of cardiovascular events, especially in the first years.

Thyroid dysfunction and dyslipidemia in chronic kidney disease patients

BACKGROUND

Chronic kidney disease (CKD) is becoming a serious health problem; the number of people with impaired renal function is rapidly rising. Progression of CKD is associated with having a number of complications, including thyroid dysfunction, dyslipidemia and cardiovascular diseases. This study was conducted to investigate thyroid function and lipid profile in CKD patients.

METHODS

A cross-sectional study was conducted among 360 chronic kidney disease patients at B P Koirala Institute of Health Sciences, Dharan, Nepal. Demographic features (age and sex) and medical history of diabetes mellitus, hypertension and cardiovascular diseases of each patient were noted, and blood samples (5 ml) were analyzed for serum urea, creatinine, glucose, free triiodothyronine (T3), free thyroxine (T4), thyroid stimulating hormone (TSH), total cholesterol, high density lipoprotein (HDL) cholesterol, low density lipoprotein (LDL) cholesterol and triglyceride.

RESULTS

Thyroid dysfunction was found in 38.6 % CKD patients, the most common being subclinical hypothyroidism (27.2 %), followed by overt hypothyroidism (8.1 %) and subclinical hyperthyroidism (3.3 %). Hypercholesterolemia, low HDL cholesterol, undesirable LDL cholesterol and hypertriglyceridemia were observed in 34.4, 34.1, 35 and 36.6 % patients respectively. Stage 4 and 5 CKD patients had significantly higher risk of having thyroid dysfunction as compared to stage 3 patients. Significant risk factors for cardiovascular disease in CKD patients included presence of diabetes mellitus, hypercholesterolemia, undesirable LDL cholesterol and being in stage 4 and 5 (as compared to stage 3).

CONCLUSIONS

Thyroid dysfunction, hypercholesterolemia, low HDL cholesterol, undesirable LDL cholesterol and hypertriglyceridemia are common in CKD patients. Progression of CKD is accompanied by rise in hypothyroidism and cardiovascular disease.

Correction of metabolic acidosis in hemodialysis: consequences on serum leptin and mineral metabolism

PURPOSE

Hyperleptinemia and metabolic acidosis (MA) are frequently observed in patients on hemodialysis (HD). While the role of leptin in patients on HD is not completely understood, HD only partially corrects MA. Both leptin and acidosis have effect on bone disease. The goal of the present study was to evaluate the effects of MA correction on chronic kidney disease-mineral and bone disorder laboratory parameters and leptin levels.

METHODS

Forty-eight patients on HD, aged 43±19 years, were prospectively studied. Individual adjustments in the bicarbonate dialysate concentration were made to maintain pre-dialysis concentration≥22 mEq/l. Blood gas analysis was done monthly for 4 months (M1-M4).

RESULTS

From M0 to M4, serum albumin increased (from 3.5 ±0.3 to 4.0±0.3 g/l, p<0.0001) while β2 microglobulin decreased (from 27.6±8.3 to 25.8±6.8 µg/ml, p=0.025). Serum leptin decreased in all but three patients, as well as leptin/adiponectin ratio (p<0.0001). There was a decrease in ionized serum calcium (from 5.0±0.5 to 4.7±0.5 mg/dl, p =0.002) and an increase in parathyroid hormone (PTH) [from 191 (85, 459) to 446 pg/ml (212, 983), p<0.0001] and in serum phosphate (from 5.4±1.4 to 5.8±1.1 mg/dl, p=0.048).

CONCLUSION

MA correction in HD patients can decrease leptin, an atherogenic marker. The impact of such treatment extends to uremic bone disease, as decrease in serum calcium and increase in PTH. However, this could be an undesirable effect because it may aggravate a secondary hyperparathyroidism. Whether the reduction in leptin levels has impact on outcomes in patients on hemodialysis deserves further investigation.

Fat-specific DsbA-L overexpression promotes adiponectin multimerization and protects mice from diet-induced obesity and insulin resistance

The antidiabetic and antiatherosclerotic effects of adiponectin make it a desirable drug target for the treatment of metabolic and cardiovascular diseases. However, the adiponectin-based drug development approach turns out to be difficult due to extremely high serum levels of this adipokine. On the other hand, a significant correlation between adiponectin multimerization and its insulin-sensitizing effects has been demonstrated, suggesting a promising alternative therapeutic strategy. Here we show that transgenic mice overexpressing disulfide bond A oxidoreductase-like protein in fat (fDsbA-L) exhibited increased levels of total and the high-molecular-weight form of adiponectin compared with wild-type (WT) littermates. The fDsbA-L mice also displayed resistance to diet-induced obesity, insulin resistance, and hepatic steatosis compared with WT control mice. The protective effects of DsbA-L overexpression on diet-induced insulin resistance, but not increased body weight and fat cell size, were significantly decreased in adiponectin-deficient fDsbA-L mice (fDsbA-L/Ad(-/-)). In addition, the fDsbA-L/Ad(-/-) mice displayed greater activity and energy expenditure compared with adiponectin knockout mice under a high-fat diet. Taken together, our results demonstrate that DsbA-L protects mice from diet-induced obesity and insulin resistance through adiponectin-dependent and independent mechanisms. In addition, upregulation of DsbA-L could be an effective therapeutic approach for the treatment of obesity and its associated metabolic disorders.

Effects of thyroxin therapy on different analytes related to obesity and inflammation in dogs with hypothyroidism

Hypothyroidism in dogs is accompanied by changes in intermediary metabolism including alterations in bodyweight (BW), insulin resistance, and lipid profile. In this study, changes in selected adipokines (adiponectin, leptin), butyrylcholinesterase (BChE), and acute phase proteins, including C-reactive protein, haptoglobin (Hp) and serum amyloid A (SAA), were studied in dogs with hypothyroidism under thyroxin therapy. Blood samples were collected when hypothyroidism was diagnosed (before treatment) and after treatment with thyroxin. Twenty-eight of 39 dogs exhibited a good therapeutic response (group A), whereas the remainder were considered to have been insufficiently treated (group B). Following treatment, group A dogs demonstrated a statistically significant decrease in canine thyroid stimulating hormone (c-TSH) (P<0.001) and an increase in free thyroxine (fT4) (P<0.001) concentrations, associated with a significant decrease in BW (P<0.05), leptin (P<0.01), and adiponectin, (P<0.001) and an increase in BChE (P<0.01) and Hp (P<0.05). Group B dogs showed no statistically significant changes in c-TSH, but had a significant increase in fT4 (P<0.001) accompanied by a significant decrease in adiponectin (P<0.05) of lower magnitude than group A. No significant changes in the mean circulating levels of APPs were observed in both groups, with the exception of an increase in Hp (P<0.05) in group A. In summary, the successful treatment of hypothyroidism reduces circulating levels of adiponectin and leptin, while increasing BChE activity in dogs. The mean increase in Hp values and decrease in SAA for some of the dogs after treatment warrants further investigation.

Lower free thyroxin associates with a less favorable metabolic phenotype in healthy pregnant women

CONTEXT

A lower free T(4) (fT4), within the euthyroid range, has been shown in adults to associate with an adverse metabolic phenotype. Thyroid physiology changes significantly during gestation and affects maternal and fetal well-being.

OBJECTIVE

The aim of the study was to test the hypothesis that a lower serum fT4 in healthy euthyroid pregnant women is related to a less favorable metabolic phenotype and to fetal or placental weight. DESIGN, SETTING, PATIENTS, AND OUTCOME MEASURES: We examined associations of thyroid function tests (TSH and fT4) and the free T(3) (fT3)-to-fT4 ratio (as a proxy of deiodinase activity) with a metabolic profile [preload and postload glucose, glycosylated hemoglobin (HbA1c), high molecular-weight (HMW)-adiponectin, homeostasis model of assessment for insulin resistance (HOMA-IR), and serum lipids] in 321 healthy pregnant women. All women were euthyroid and had negative anti-thyroid peroxidase antibodies. None received thyroid hormone replacement. Blood tests were performed in women between 24 and 28 wk gestation. Placentas and newborns were weighed at birth.

RESULTS

Circulating TSH did not relate to metabolic parameters, but decreasing fT4 and increasing fT3-to-fT4 ratio associated with a less favorable metabolic phenotype, as judged by higher postload glucose, HbA1c, fasting insulin, HOMA-IR, and triglycerides, and by a lower HMW-adiponectinemia (all P ≤ 0.005). In multiple regression analyses, fT4 was independently associated with HbA1c (β = -0.135; P = 0.038), HMW-adiponectin (β = 0.218; P < 0.001), and placental weight (β = -0.185; P < 0.005), whereas the fT3-to-fT4 ratio was independently associated with maternal body mass index (β = 0.265; P < 0.001), HMW-adiponectinemia (β = -0.237; P < 0.002), HOMA-IR (β = 0.194; P = 0.014), and placental weight (β = 0.174; P = 0.020).

CONCLUSION

In pregnant women without a history of thyroid dysfunction, lower concentrations of fT4 and a higher conversion of fT4 to fT3, as inferred by changes in the fT3-to-fT4 ratio, were found to be associated with a less favorable metabolic phenotype and with more placental growth.

Plasma adiponectin concentration and left ventricular hypertrophy in kidney transplant patients

BACKGROUND

Low plasma adiponectin concentration is associated with more frequent occurrence of left ventricular hypertrophy (LVH) and more exaggerated intima-media thickness of common carotid artery (IMT). IMT is an early surrogate marker of atherosclerosis. This study aimed to assess the relationship between plasma adiponectin concentration and left ventricular mass index (LVMI) and IMT in kidney transplant patients (KTP).

METHODS

In 88 adult KTP, plasma adiponectin concentration, LVMI, and IMT were estimated. LVH was defined as LVMI >110 or >125 g/m(2) for females and males, respectively. Data presented are means and 95% CI.

RESULTS

Plasma adiponectin concentration was similar in KTP with (n = 42) or without LVH (n = 46) (13.5 [11.4-15.6] vs. 13.1 [11.6-14.6] μg/mL, respectively), as well as in KTP subgroups divided according to the IMT value tertiles (p = 0.42) (11.7 [10.0-13.3], 14.2 [11.7-16.6], and 14.0 [11.7-16.4] μg/mL in the lowest, middle, and highest tertiles, respectively). Plasma glucose concentrations were similar in KTPs with LVH or without LVH. No significant correlation was found between plasma adiponectin concentration and both LVMI (R = -0.02; p = 0.87) and IMT (R = 0.09; p = 0.38), respectively.

CONCLUSION

Results of this cross-sectional study do not confirm the roles of low adiponectin and high glucose in the pathogenesis of LVH and atherosclerosis in KTP.

Circulating adiponectin concentrations were related to free thyroxine levels in thyroid cancer patients after thyroid hormone withdrawal

Because it is unclear whether adipose-derived hormones are related to thyroid hormone metabolism, this study evaluated the relationship between adiponectin concentrations and changes in the thyroid hormones in athyreotic patients after thyroid hormone withdrawal. Twenty-eight athyreotic thyroid cancer patients (4 male and 24 female; mean age, 52.2 +/- 11.3 years) were analyzed on the final day of levothyroxine treatment and 1 day before serum thyroglobulin and radioiodine scanning examinations after an average of 4 weeks of thyroid hormone withdrawal. Evaluations included analysis of thyroid function test, serum adiponectin, body composition by bioimpedance analysis, and insulin sensitivity index as determined by the homeostasis model assessment of insulin resistance (HOMA-IR). Discontinuation of thyroid hormone treatment resulted in a significant change in thyroid-stimulating hormone (82.1 +/- 9.8 vs 1.0 +/- 0.4 mL/L, P < .05), free thyroxine (FT4) (5.7 +/- 0.4 vs 18.7 +/- 2.3 pmol/L, P < .05), and free triiodothyronine levels (1.8 +/- 0.2 vs 3.4 +/- 0.2 pmol/L, P < .05) as compared with the prewithdrawal values, whereas circulating adiponectin levels (5.7 +/- 0.6 vs 5.4 +/- 0.6 mg/L), body fat mass (20.3 +/- 1.2 vs 19.4 +/- 1.2 kg), and insulin sensitivity index (1.8 +/- 0.2 vs 2.2 +/- 0.3) remained unaltered. A positive correlation between adiponectin and FT4 (r = 0.61, P < .01) independent of age, sex, fat body mass, HOMA-IR, and other potential covariates known to affect thyroid hormone metabolism, such as renal and liver functions, was observed after thyroid hormone withdrawal. In addition, baseline circulating adiponectin levels were correlated with a diminished postwithdrawal reduction of FT4 concentrations after adjusting for baseline FT4 levels and changes in body mass index, fat body mass, and HOMA-IR (r = 0.71, P < .01). In conclusion, adiponectin concentrations were associated with FT4 levels in the athyreotic patients after thyroid hormone withdrawal. The relevant roles of adiponectin in the regulation of thyroid hormone metabolism require further investigation.

Adiponectin in patients with chronic kidney disease

Adiponectin is one of many so called "adipokines"--cytokines, chemokines, growth factors, and complement proteins secreted by adipose tissue--that can affect the function of other organs. This antiatherogenic and insulin-sensitizing polypeptide is eliminated from the circulation mostly by the kidneys. Thus, in patients with chronic kidney disease, adiponectin accumulates in the circulation; its plasma concentration is approximately three times higher in end stage kidney disease than in healthy subjects. As no biological consequences of these unusually high adiponectin concentrations have been demonstrated, this polypeptide cannot be considered as a uremic toxin. On the contrary, inadequately low instead of high plasma adiponectin concentration is recognized as a new nontraditional risk factor of cardiovascular morbidity and mortality in these patients. This review summarizes the causes and clinical consequences of adiponectin accumulation in the circulation of patients with chronic kidney disease.

Determinants of plasma adiponectin levels in nondiabetic subjects with moderate to severe chronic kidney disease

OBJECTIVE

Our objective was to determine factors associated with adiponectin levels in subjects with stage III to IV chronic kidney disease (CKD).

DESIGN

We used a cross-sectional analysis.

SETTING

All kidney-disease subjects and controls were recruited at Vanderbilt University Medical Center (Nashville, TN) and Maine Medical Center (Portland, ME).

PATIENTS

We recruited 95 stage III to IV CKD subjects. Kidney-disease subjects with history of diabetes mellitus were excluded from the study.

INTERVENTIONS

There were no interventions.

RESULTS

Subjects with stage IV CKD had significantly higher adiponectin levels compared with those with stage III CKD (30.6 +/- 22.8 microg/mL vs. 21.1 +/- 14.6 microg/mL mean +/- SD, P = .05). Adiponectin was significantly correlated with gender (P = .01), high-density lipoproteins (P < .001), triglycerides (P = .004), and weight (P = .04) upon unadjusted analysis. Using multiple linear regression analysis, gender (P = .03), high-density lipoproteins (P = .001), triglycerides (P = .04), and high-sensitivity C-reactive protein (P = .004) were independently associated with adiponectin.

CONCLUSIONS

Gender, high-density lipoproteins, triglycerides, and high-sensitivity C-reactive protein are major determinants of adiponectin levels in nondiabetic stage III to IV CKD. Insulin resistance, body mass index, and body fat percentage were not associated with adiponectin levels. Plasma adiponectin levels are difficult to interpret in the setting of CKD because of multiple confounders that may influence the relationship between adiponectin, adiposity, and insulin resistance.

Normalization of endothelial dysfunction following renal transplantation is accompanied by a reduction of circulating visfatin/NAMPT. A novel marker of endothelial damage?

Endothelial dysfunction is strongly linked to cardiovascular disease and outcome of patients with chronic kidney disease. We hypothesized that decreased inflammatory activity and increased adiponectin following transplantation could be one mechanism for a better endothelial health. Fifty-eight living donor kidney transplant non-diabetic recipients, 31 (23 male, 29 +/- 5 yr) on cyclosporine A and 27 (10 male, 26 +/- 5 yr) on tacrolimus immunsupression, were studied longitudinally. Visfatin, adiponectin, high sensitive C-reactive protein (hsCRP) levels, brachial artery flow mediated dilatation (FMD) and nitroglycerine mediated dilatation were measured before transplantation and on the 30th and 90th day after transplantation. Pre-transplantation visfatin, adiponectin and FMD values of patients were significantly higher than those of the controls (p < 0.001 for all). All values decreased significantly 30 and 90 d post-transplantation. Plasma visfatin and adiponectin, correlated negatively with FMD levels 90 d both before and after kidney transplantation (p < 0.001 for both). Endothelial function improved during the first month after transplantation, and the degree of improvement correlated to reductions in circulating visfatin, adiponectin and hsCRP levels. Of interest, the intracellular enzyme visfatin was the strongest predictor of FMD both before and after kidney transplantation and may thus reflect endothelial cell damage directly.

Adipocytokines leptin and adiponectin, and measures of malnutrition-inflammation in chronic renal failure: is there a relationship?

BACKGROUND

Serum levels of adipocytokines such as leptin and adiponectin are significantly elevated in patients with chronic renal failure (CRF). The effect of such adipocytokines on malnutrition in the CRF population has been of substantial interest. We sought to determine the relationship between plasma leptin and adiponectin levels and malnutrition-inflammation status in end-stage renal disease patients.

METHODS

Thirty patients (15 women and 15 men; mean [+/-SD] age, 50 +/- 14 years) on hemodialysis, and 30 patients (12 women and 18 men; mean [+/-SD] age, 47 +/- 16) on continuous ambulatory peritoneal dialysis, were enrolled in this study. Adipocytokine levels were measured by enzyme-linked immunosorbent assay. Inflammatory markers, such as high-sensitivity serum C-reactive protein (hs-CRP), ferritin, and a nutritional inflammatory scoring system known as the malnutrition-inflammation score (MIS), were also measured in all patients.

RESULTS

Serum leptin had negative correlations with ferritin (r = -0.33, P = .016) and MIS (r = -0.39, P = .003). Adiponectin had a weak positive correlation with MIS (r = 0.26, P = .050), indicating that an increased level of serum adiponectin was associated with a worse nutritional status. Levels of hs-CRP, serum albumin, cholesterol, and triglycerides did not correlate with nutritional status.

CONCLUSIONS

Serum leptin concentration seems to be a marker of good nutritional status, rather than an appetite-suppressing uremic toxin, in patients with CRF. However, the positive correlation between serum adiponectin and worse nutritional-inflammatory status suggests that elevated adiponectin levels may contribute to the pathogenesis of malnutrition in such patients.

Role of leptin in reverse epidemiology in chronic kidney disease

Leptin is mainly produced by adipocytes and metabolized in the kidney. Leptin is taken up into the central nervous system by a saturable transport system, and controls appetite in rodents and in healthy subjects. Leptin acts on peripheral tissue and increases the inflammatory response by stimulating the production of tumor necrosis factor alpha, interleukin-6 and interleukin-12. In healthy humans, serum leptin concentration is related to the size of adipose tissue mass in the body. The majority of obese subjects have inappropriately high levels of circulating plasma leptin concentrations, indicating leptin resistance. In healthy subjects increased leptin concentration constitutes a biomarker for increased cardiovascular risk. On the other hand, a recent prospective long-term study in patients with chronic kidney disease stage 5 on hemodialysis therapy showed that reduced serum leptin concentration is an independent risk factor for mortality in these patients.

Low serum leptin predicts mortality in patients with chronic kidney disease stage 5

OBJECTIVE

Leptin, secreted from adipose tissue, regulates food intake, energy expenditure, and immune function. It is unknown whether leptin predicts mortality in patients with chronic kidney disease stage 5 on hemodialysis therapy.

RESEARCH METHODS AND PROCEDURES

We performed a prospective cohort study of 71 patients with chronic kidney disease stage 5 in an outpatient hemodialysis center. Subjects were recruited in June 1998 and followed for 83 months. Survival was compared by the Kaplan-Meier method.

RESULTS

After 83 months of follow-up, 48 patients (68%) had died. Serum leptin concentrations at study entry were lower among all deceased patients compared with those patients who survived (5.2 +/- 9.0 microg/L; n = 48; vs. 7.7 +/- 7.8 microg/L; n = 23; p = 0.005). Baseline serum leptin concentrations were significantly lower in patients who died from cardiovascular diseases (4.7 +/- 9.4 microg/L, n = 32) or infections (4.0 +/- 2.7 microg/L; n = 10; each p < 0.05), but not cancer (9.4 +/- 7.9 microg/L; n = 6), than in survivors (7.7 +/- 7.8 microg/L; n = 23; p = 0.003). The relative risk for mortality in patients with serum leptin concentrations below the median (<2.6 microg/L) compared with patients above the median was 1.96 (95% confidence interval, 1.01 to 3.79; p = 0.04). Survival was shorter in patients with leptin concentrations below the median compared with those whose leptin concentrations were above the median (all-cause mortality, chi(2) = 5.05; p = 0.02).

DISCUSSION

Low serum leptin concentration is an independent predictor of mortality in patients with chronic kidney disease stage 5 on hemodialysis therapy.

Thyroid Function, Endothelium, and Inflammation in Hemodialyzed Patients: Possible Relations?

OBJECTIVE

Renal function affects the thyroid gland in many ways. Disturbances in hemostasis and inflammation are common complications of kidney diseases. Endothelial dysfunction may link these two processes.

DESIGN AND PATIENTS

A cross-sectional study on thyroid hormones in relation to markers of endothelial damage and inflammation in 96 hemodialyzed (HD) patients and 39 healthy volunteers was performed.

SETTING

The study took place in the dialysis unit at a university hospital.

INTERVENTION

Thyroid hormones, markers of endothelial damage (von Willebrand factor, thrombomodulin, intracellular adhesion molecule, and CD146), markers of inflammation (high-sensitivity C-reactive protein, tumor necrosis factor alpha), other hemostatic parameters (thrombin-antithrombin complexes, prothrombin fragments 1 + 2 - F1 + 2, plasmin-antiplasmin complexes, tissue plasminogen activator and its inhibitor, tissue factor pathway inhibitor, and platelet glycoprotein V) were measured using commercially available kits.

RESULTS

Free T3 and total T3 were lower in HD patients compared with controls. Markers of endothelial dysfunction and inflammation were significantly elevated in HD patients compared with controls. In multiple regression analysis T3 was independently related to time on dialyses, albumin, iron, ferritin, C-reactive protein (CRP), and F1 + 2 in HD patients. Free T3 was also independently related to total protein, total calcium, and triglycerides. In patients with CRP less than 6 mg/L in multiple regression analysis the only correlates of T3 were albumin and ferritin, whereas the only correlates of free T3 were albumin and time on dialyses. Multiple regression analysis showed that in HD patients with CRP greater than equal to 6 mg/L predictors of free T3 were CRP, F1 + 2, and dose of erythropoietin. In healthy volunteers T3 was related to tissue factor pathway inhibitor and platelet glycoprotein V was related to thyroid-stimulating hormone.

CONCLUSIONS

We described novel relations between thyroid hormones and markers of endothelial dysfunction and inflammation in HD patients. Thyroid dysfunction is related to time on dialyses, endothelial damage, and inflammatory state, frequently encountered in uremia. Therefore, the relations between thyroid axis and endothelium in HD subjects merit additional studies.

Possible Relations Between Thyroid Function, Endothelium, and Kidney and Liver Function in Kidney Allograft Recipients

BACKGROUND

Renal function affects the thyroid gland in many ways. Disturbances in hemostasis and endothelial damage are common complications of kidney disease. Endothelial dysfunction may link these two processes.

AIM AND METHODS

This cross-sectional study examined thyroid hormones in relation to markers of endothelial damage and inflammation among 80 kidney allograft recipients and 29 healthy volunteers. Thyroid hormones, markers of endothelial damage (vWF, thrombomodulin, intracellular adhesion molecule [ICAM] vascular adhesion molecule [VCAM], CD146), markers of inflammation (hsCRP), other hemostatic parameters (thrombin-antithrombin complexes [TAT], prothrombin fragments 1 + 2 [F1 + 2], plasmin-antiplasmin complexes, tissue plasminogen activator and its inhibitor, platelet glycoprotein [V-GPV]) as well as P-selectin were measured using commercially available kits.

RESULTS

Total T3 was significantly lower among kidney allograft recipients, whereas markers of endothelial dysfunction and inflammation were significantly elevated over controls. In kidney allograft recipients total T3 was independently related to PAI-1, ICAM, and eGFR, whereas free T3 was independently related to thrombomodulin, aspartate, and alanine aminotransferases, hemoglobin, urea, eGFR, dose of cyclosporine and treatment with mycophenolate mofetil/azathioprine. Total T4 was related to aspartate and alanine aminotransferases, dose of cyclosporine, PAI-1, and ICAM. In multiple regression analysis the only correlates of T3 were PAI-1 and ICAM, whereas the only correlates of free T3 were thrombomodulin, aspartate aminotransferase, eGFR, and cyclosporine dose. In healthy volunteers GPV was related only to TSH.

CONCLUSIONS

We described novel relations between thyroid hormones and markers of endothelial dysfunction in kidney transplant recipients. In kidney transplant recipients thyroid function metrics were associated with endothelial damage, immunosuppressive treatment, liver and kidney function. Therefore, the relations between thyroid axis and endothelium in kidney allograft recipients merit additional studies.