AQP1 Promoter Variant, Water Transport, and Outcomes in Peritoneal Dialysis.

BACKGROUND: Variability in ultrafiltration influences prescriptions and outcomes in patients with kidney failure who are treated with peritoneal dialysis. Variants in AQP1, the gene that encodes the archetypal water channel aquaporin-1, may contribute to that variability. METHODS: We gathered clinical and genetic data from 1851 patients treated with peritoneal dialysis in seven cohorts to determine whether AQP1 variants were associated with peritoneal ultrafiltration and with a risk of the composite of death or technique failure (i.e., transfer to hemodialysis). We performed studies in cells, mouse models, and samples obtained from humans to characterize an AQP1 variant and investigate mitigation strategies. RESULTS: The common AQP1 promoter variant rs2075574 was associated with peritoneal ultrafiltration. Carriers of the TT genotype at rs2075574 (10 to 16% of patients) had a lower mean (±SD) net ultrafiltration level than carriers of the CC genotype (35 to 47% of patients), both in the discovery phase (506±237 ml vs. 626±283 ml, P = 0.007) and in the validation phase (368±603 ml vs. 563±641 ml, P = 0.003). After a mean follow-up of 944 days, 139 of 898 patients (15%) had died and 280 (31%) had been transferred to hemodialysis. TT carriers had a higher risk of the composite of death or technique failure than CC carriers (adjusted hazard ratio, 1.70; 95% confidence interval [CI], 1.24 to 2.33; P = 0.001), as well as a higher risk of death from any cause (24% vs. 15%, P = 0.03). In mechanistic studies, the rs2075574 risk variant was associated with decreases in AQP1 promoter activity, aquaporin-1 expression, and glucose-driven osmotic water transport. The use of a colloid osmotic agent mitigated the effects of the risk variant. CONCLUSIONS: A common variant in AQP1 was associated with decreased ultrafiltration and an increased risk of death or technique failure among patients treated with peritoneal dialysis. (Funded by the Swiss National Science Foundation and others.).

Increased miR-7641 Levels in Peritoneal Hyalinizing Vasculopathy in Long-Term Peritoneal Dialysis Patients.

Peritoneal hyalinizing vasculopathy (PHV) represents the cornerstone of long-term peritoneal dialysis (PD), and especially characterizes patients associated with encapsulating peritoneal sclerosis. However, the mechanisms of PHV development remain unknown. A cross sectional study was performed in 100 non-selected peritoneal biopsies of PD patients. Clinical data were collected and lesions were evaluated by immunohistochemistry. In selected biopsies a microRNA (miRNA)-sequencing analysis was performed. Only fifteen patients (15%) showed PHV at different degrees. PHV prevalence was significantly lower among patients using PD fluids containing low glucose degradation products (GDP) (5.9% vs. 24.5%), angiotensin converting enzyme inhibitors (ACEIs) (7.5% vs. 23.4%), statins (6.5% vs. 22.6%) or presenting residual renal function, suggesting the existence of several PHV protective factors. Peritoneal biopsies from PHV samples showed loss of endothelial markers and induction of mesenchymal proteins, associated with collagen IV accumulation and wide reduplication of the basement membrane. Moreover, co-expression of endothelial and mesenchymal markers, as well as TGF-ß1/Smad3 signaling activation were found in PHV biopsies. These findings suggest that an endothelial-to-mesenchymal transition (EndMT) process was taking place. Additionally, significantly higher levels of miR-7641 were observed in severe PHV compared to non-PHV peritoneal biopsies. Peritoneal damage by GDPs induce miRNA deregulation and an EndMT process in submesothelial vessels, which could contribute to collagen IV accumulation and PHV.

COVID-19 incidence and outcomes in a home dialysis unit in Madrid (Spain) at the height of the pandemic.

INTRODUCTION: The 2019 coronavirus (COVID-19) is a viral infection caused by a new coronavirus that is affecting the entire world. There have been studies of patients on in-center hemodialysis (HD), but home dialysis population data are scarce. Our objective is to study the incidence and course of COVID-19 in a home dialysis unit (HDU) at the height of the pandemic. METHODS: an observational, retrospective study enrolling all patients diagnosed with COVID-19 from the HDU of Hospital Universitario La Paz [La Paz University Hospital] (Madrid, Spain) between March 10 and May 15, 2020. We collected clinical data from the HDU (57 patients on peritoneal dialysis [PD] and 22 patients on home hemodialysis [HHD]) and compared the clinical characteristics and course of patients with and without COVID-19 infection. RESULTS: twelve patients were diagnosed with COVID-19 (9 PD; 3 HHD). There were no statistically significant differences in terms of clinical characteristics between patients with COVID-19 and the rest of the unit. The mean age was 62 ± 18.5 years; most were men (75%). All patients but one required hospitalization. Ten patients (83%) were discharged following a mean of 16.4 ± 9.7 days of hospitalization. Two patients were diagnosed while hospitalised for other conditions, and these were the only patients who died. Those who died were older than those who survived. CONCLUSION: The incidence of COVID-19 in our HDU in Madrid at the height of the pandemic was high, especially in patients on PD. No potential benefit for preventing the infection in patients on home dialysis was observed. Advanced age and nosocomial transmission were the main factors linked to a worse prognosis.

[COVID-19 incidence and outcomes in a home dialysis unit in Madrid (Spain) at the height of the pandemic]. / Incidencia y resultados de la COVID-19 en una unidad de diálisis domiciliaria en Madrid (España) durante el pico de la pandemia.

INTRODUCTION: The 2019 coronavirus (COVID-19) is a viral infection caused by a new coronavirus that is affecting the entire world. There have been studies of patients on in-center hemodialysis, but home dialysis population data are scarce. Our objective is to study the incidence and course of COVID-19 in a home dialysis unit (HDU) at the height of the pandemic. METHODS: An observational, retrospective study enrolling all patients diagnosed with COVID-19 from the HDU of Hospital Universitario La Paz (La Paz University Hospital) (Madrid, Spain) between March 10 and May 15, 2020. We collected clinical data from the HDU (57 patients on peritoneal dialysis and 22 patients on home hemodialysis) and compared the clinical characteristics and course of patients with and without COVID-19 infection. RESULTS: Twelve patients were diagnosed with COVID-19 (9 peritoneal dialysis; 3 home hemodialysis). There were no statistically significant differences in terms of clinical characteristics between patients with COVID-19 and the rest of the unit. The mean age was 62±18.5 years; most were men (75%). All patients but one required hospitalization. Ten patients (83%) were discharged following a mean of 16.4±9.7 days of hospitalization. Two patients were diagnosed while hospitalized for other conditions, and these were the only patients who died. Those who died were older than those who survived. CONCLUSION: The incidence of COVID-19 in our HDU in Madrid at the height of the pandemic was high, especially in patients on peritoneal dialysis. No potential benefit for preventing the infection in patients on home dialysis was observed. Advanced age and nosocomial transmission were the main factors linked to a worse prognosis.

The ideal position of the peritoneal dialysis catheter is not always ideal.

PURPOSE: Peritoneal catheter dysfunction is a frequent complication of peritoneal dialysis (PD). Traditionally, dysfunction has been attributed to catheter malposition, but whether the location of the catheter tip in the small pelvis really determines proper function is unclear. METHODS: We reviewed 900 abdominal X-ray images of PD patients from a 7-year period in two PD units that use different catheter types (straight and Swan Neck Curled). RESULTS: In 52% of the images, the dialysis catheter tip was located in the ideal position in the small pelvis and in 48% in other sites. Peritoneal catheter function was normal at the time of imaging in 87% of those with ideal catheter tip position, and in 74% of those with other than ideal position. The tip was located in small pelvis in 35% of images performed during catheter dysfunction and in 56% of those performed during normal catheter function. There were no differences between two catheter types. The positive predictive value of abdominal X-ray images to predict catheter function was 26%, and the negative predictive value 87%. We also found a significant positive correlation between polycystic kidney disease and normal catheter function. In contrast, obese patients were more likely to have catheter malfunction. Previous abdominal surgery was not associated with catheter dysfunction. CONCLUSION: Our data showed a higher probability of normal function of peritoneal catheters whose tips were located in the small pelvis. However, also malpositioned catheters generally functioned well, and malpositioning of the PD catheter did not in itself explain its malfunction.

Cross-sectional study of quality of life in relation with vascular access in hemodialysis patients. Study in a hospital and a satellite center

Introduction: Vascular access for hemodialysis (HD) is essential for the patient. Even though Arteriovenous fistula (AVF) is the preferred access, in certain age groups, the central venous catheter (CVC) may provide advantages. This study aims to investigate the quality of life related to vascular access. Methods: Cross-sectional study including patients from a hospital, a home HD unit and a satellite hemodialysis center. Clinical data was collected from the patients, who went through a quality-of-life questionnaire SF12 and a Vascular Access Questionnaire (VAQ). Results: 91 patients participated, mostly male (70 %), with a mean age of 68.9 ± 16.2 years. AVF was the current vascular access in 60.4 %, the rest used a CVC. Home HD was performed in 12.1 % of patients and 76 % started it via CVC. Regarding patients who have had both AVF and CVC, 58 % prefer AVF and only 26.5 % of current CVC carriers would have a new AVF, mostly due to fear of pain (52 %). Most people (72.5 %) reported having received sufficient information, with no differences between both accesses. The SF12 results showed no differences between patients with AVF or CVC. Regarding the VAQ, patients with AVF were more satisfied with the social aspect (p = 0.036) and complications (p = 0.006). Conclusion: Patients with AVF had better outcomes than those using CVC regarding complications and social aspects. These differences are not attributable to a worse overall quality of life status of CVC patients. Most patients with CVCs refuse to go through a new AVF for fear of puncture pain.

Introducción: el acceso vascular para la hemodiálisis (HD) es esencial para el paciente. Aunque la fístula arteriovenosa (FAV) es el acceso preferido, en ciertos grupos de edad el catéter venoso central (CVC) puede aportar ventajas. Este estudio pretende investigar la calidad de vida relacionada con el acceso vascular. Métodos: el estudio transversal incluye pacientes del hospital, de una unidad de HD domiciliaria y de un centro de hemodiálisis periférico. Se recogieron datos clínicos de los pacientes que contestaron el cuestionario de calidad de vida SF12 y Cuestionario de Acceso Vascular (VAQ). Resultados: 91 pacientes, en su mayoría varones (70 %), con una edad media de 68,9 ± 16,2 años. La FAV era el acceso vascular actual en el 60,4 %. La HD domiciliaria se realizó en el 12,1 % de los pacientes y el 76 % la inició mediante CVC. En cuanto a los pacientes que han tenido tanto FAV como CVC, el 58 % prefiere la FAV y sólo el 26,5 % de los actuales portadores de CVC se sometería a una nueva FAV, sobre todo por miedo al dolor (52 %). La mayoría de las personas (72,5 %) declararon haber recibido suficiente información, sin diferencias entre ambos accesos. Los resultados del SF12 no mostraron diferencias según el acceso. En cuanto al VAQ, los pacientes con AVF estaban más satisfechos con el aspecto social y las complicaciones. Conclusión: los pacientes con FAV tuvieron mejores resultados en comparación con los que utilizaron CVC en cuanto a complicaciones y aspectos sociales, sin deberse a un peor estado general de la calidad de vida. La mayoría de los pacientes con CVC se niegan a someterse a una nueva FAV por miedo al dolor de la punción.

Nebivolol, a ß1-adrenergic blocker, protects from peritoneal membrane damage induced during peritoneal dialysis.

UNLABELLED: Peritoneal dialysis (PD) is a form of renal replacement treatment, which employs the peritoneal membrane (PM) to eliminate toxins that cannot be removed by the kidney. The procedure itself, however, contributes to the loss of the PM ultrafiltration capacity (UFC), leading consequently to the technique malfunction. ß-blockers have been considered deleterious for PM due to their association with loss of UFC and induction of fibrosis. Herein we analyzed the effects of Nebivolol, a new generation of ß1-blocker, on PM alterations induced by PD fluids (PDF).In vitro: We found that mesothelial cells (MCs) express ß1-adrenergic receptor. MCs were treated with TGF-ß to induce mesothelial-to-mesenchymal transition (MMT) and co-treated with Nebivolol. Nebivolol reversed the TGF-ß effects, decreasing extracellular matrix synthesis, and improved the fibrinolytic capacity, decreasing plasminogen activator inhibitor-1 (PAI-1) and increasing tissue-type plasminogen activator (tPA) supernatant levels. Moreover, Nebivolol partially inhibited MMT and decreased vascular endothelial growth factor (VEGF) and IL-6 levels in supernatants.In vivo: Twenty-one C57BL/6 mice were divided into 3 groups. Control group carried a catheter without PDF infusion. Study group received intraperitoneally PDF and oral Nebivolol during 30 days. PDF group received PDF alone. Nebivolol maintained the UFC and reduced PM thickness, MMT and angiogenesis promoted by PDF. It also improved the fibrinolytic capacity in PD effluents decreasing PAI-1 and IL-8 and increased tPA levels. CONCLUSION: Nebivolol protects PM from PDF-induced damage, promoting anti-fibrotic, anti-angiogenic, anti-inflammatory and pro-fibrinolytic effects.

Malnutrition-inflammation syndrome is associated with endothelial dysfunction in peritoneal dialysis patients.

Endothelial dysfunction with atherosclerosis is a recognized complication of uremic patients. The hypoalbuminemia of peritoneal dialysis (PD) patients can induce a hypercoagulable and atherogenic state. In this study, we investigated the role played by malnutrition-inflammation syndrome on endothelial function markers in PD patients. We measured markers of nutrition [normalized protein catabolic rate (nPCR), albumin, prealbumin, insulin-like growth factor 1 (IGF-1), transferrin, and cholesterol], markers of endothelial damage and function [tissue-type plasminogen activator (tPA), thrombomodulin (TM), von Willebrand factor (vWF), and NO3 (representing NO)], markers of a coagulable state [fibrinogen and plasminogen activator inhibitor 1 (PAI-1)], markers of inflammation [tumor necrosis factor alpha (TNF alpha) and C-reactive protein (CRP)], and other endothelial injury factors [lipoprotein(a) [Lp(a)] and homocysteine]. We also performed an endothelial stimulation test consisting of right-arm venous occlusion (VO) for 10 minutes. The patients were divided into four groups according to their clinical atherosclerotic score (CAS). We studied 45 clinically stable PD patients. At baseline, statistically significant negative linear correlations were found between albumin and age (r = -0.54, p < 0.05), albumin and vWF post-VO (r = -0.54, p < 0.05), and albumin and TM (r = -0.36, p < 0.05), which are endothelial damage markers and prothrombotic factors. A positive linear correlation was seen between albumin and NO3 post-VO (r = 0.48, p < 0.05), indicating a high vasodilatation capacity. C-Reactive protein and TNF alpha showed a positive linear correlation (r = 0.5, p < 0.01). Similarly, TNF alpha showed a positive linear correlation with cardiovascular risk markers such as fibrinogen (r = 0.79, p < 0.01), PAI-1 (r = 0.44, p < 0.05), and homocysteine (r = 0.37, p < 0.05). Creatinine clearance showed a negative linear correlation with TM (r = -0.36, p < 0.05). Patients with albumin < 4 g/dL showed a lower tPA ratio, lower NO3, and a higher CRP, TNF alpha, and Lp(a) than did patients with albumin > 4 g/dL [tPA ratio: 2.1 +/- 1.56 (n = 29) vs. 2.6 +/- 2.3 (n = 16), p < 0.05; NO3: 47 +/- 27 micrograms/mL vs. 69 +/- 33 micrograms/mL, p < 0.05; CRP: 1.8 +/- 3 mg/dL vs. 1.1 +/- 1.6 mg/dL, p < 0.05; TNF alpha: 44.4 +/- 16 pg/mL vs. 36.6 +/- 21.4 pg/mL, p < 0.05; Lp(a): 55 +/- 39 mg/dL vs. 33 +/- 21 mg/dL, p < 0.05]. Patients with a worse CAS showed higher homocysteine levels and lower albumin values. Those relationships were maintained in both periods of the study. We found no relationships between dialysis dose and endothelial function markers. In conclusion, malnutrition-inflammation syndrome may contribute to endothelial dysfunction and, consequently, to prothrombotic and proatherogenic processes in PD patients.

Thyroid function tests in acute kidney injury.

OBJECTIVE: The aim of this study was to analyze the prevalence, clinical significance and prognostic implications of alterations in thyroid function tests (TFTs) in patients with acute kidney injury (AKI). METHODS: A prospective study was carried out in patients hospitalized for AKI for 2 consecutive years. TFTs (serum thyrotropin [TSH], free thyroxine [FT4] and total triiodothyronine [T3] concentrations) were completed for each patient on 3 occasions: at admission, at hospital discharge and at their first outpatient visit. TFTs were related to clinical and analytical data. Thirty-five patients (16 women [45.7%], mean age ± SD, 65.2 ± 18.0 years) with AKI (creatinine 5.6 ± 2.2 mg/dL) were studied. There were 10 (28.6%), 10 (28.6%), 11 (31.4%) and 4 (11.4%) patients with prerenal, renal, mixed (prerenal and renal), and postrenal AKI, respectively. RESULTS: Total prevalence of alterations in TFTs was 82.9% (n=29). Of those, euthyroid sick syndrome (ESS) with low T3 only was the most common (n=13, 37.1%) derangement. In the whole group of patients, median TSH (0.93 µU/mL, interquartile range 0.35-2.27 µU/mL)and mean FT4 (1.2 ± 0.3 ng/dL) were normal, whereas mean T3 was low (0.7 ± 0.1 ng/mL). TSH, FT4 and T3 were similar in different types of AKI. On simple regression analysis, we found a negative correlation only between TSH and serum urea concentrations (ro=-0.382; p=0.024). At hospital discharge (median hospital stay 6 days; range 2-10 days), TFT showed significant changes only in T3 concentrations (0.8 ± 0.3 ng/mL, p=0.013). At this point, the percentage of patients with normal TFT increased from 17.1% at baseline to 40% at discharge and then to 66.7% at their first outpatient visit. We found no association between the presence and type of alterations in TFT and clinical factors (sex, age, personal history of diabetes and/or hypertension, number and type of drugs used, number of signs and symptoms at AKI diagnosis, and degree, type and cause of AKI) or prognostic factors (hospital stay, recovery of renal function, need for renal replacement therapy by hemodialysis, development and degree of residual chronic renal failure and mortality) associated with AKI. CONCLUSION: Over 80% of AKI patients exhibit alterations in TFT. The commonest derangement is ESS (~70%), mainly low T3 syndrome, which is present in about one third of the patients with altered TFT. ESS recovers spontaneously as renal function improves. The presence of TFT alterations seems to not be associated with clinical and prognostic implications in AKI patients.

Serum ghrelin concentrations in patients with chronic renal failure undergoing dialysis.

BACKGROUND: Ghrelin is a recently discovered protein hormone mainly synthesized in the gastric endocrine cells. This hormone not only is a potent growth hormone secretagogue but also is involved in the regulation of food ingestion and energy metabolism. Derangements in ghrelin secretion in patients with chronic renal failure (CRF) have not been fully evaluated. OBJECTIVE: Our aim has been to quantify serum concentrations of total ghrelin in a group of patients with CRF on chronic therapy with both haemodialysis (HD) and peritoneal dialysis (PD) in comparison with a group of patients on conservative management (predialysis). PATIENTS AND MEASUREMENTS: We studied 68 CRF patients treated by HD (n = 30, 16 men, age 61.2 +/- 1.8 years) and PD groups (n = 38, 21 men, age 54.4 +/- 1.7 years). A group of 19 uraemic patients on conservative management served as the control. Serum concentrations of ghrelin, leptin, insulin, IGF I and GH were measured in all subjects. RESULTS: Patients undergoing HD showed similar concentrations of ghrelin in comparison with the control group (9491 +/- 787 vs 9280 +/- 918 pg/ml, NS). However, PD patients exhibited baseline ghrelin concentrations significantly lower than those found in patients on conservative management (3230 +/- 216 pg/ml, P < 0.0001). Men and women showed similar serum ghrelin levels in both HD (9845.9 +/- 1071 vs 9085 +/- 1194 pg/ml) and PD patients (3214 +/- 297 vs 3250 +/- 324 pg/ml). Hypertension and diabetes mellitus did not influence ghrelin levels. Serum GH levels were positively correlated with serum ghrelin concentrations in both HD (r = 0.46, P < 0.05) and PD (r = 0.53, P < 0.001) patients; however, no relationships between ghrelin, leptin, insulin and IGF I were found. CONCLUSIONS: These results suggest that PD is accompanied by a striking decrement in baseline ghrelin concentrations in comparison with values found both in HD and control patients. Further studies are necessary to determine mechanisms involved in ghrelin regulation in uraemic patients.

Serum concentrations of leptin, adiponectin and resistin, and their relationship with cardiovascular disease in patients with end-stage renal disease.

BACKGROUND AND OBJECTIVE: High levels of some adipocytokines have been reported in patients with chronic renal failure, but little information is available on adipocytokine concentrations in uraemic patients under different modalities of therapy. Our aims were (1) to quantify the serum concentrations of leptin, adiponectin and resistin in uraemic patients on peritoneal dialysis (PD) and haemodialysis (HD), in comparison with patients on conservative management, and (2) to study the relationships between adipocytokine levels and previous atherosclerotic vascular disease. PATIENTS AND MEASUREMENTS: We studied 82 dialysis patients treated by PD (n = 44, 23 males and 21 females, mean age 54.4 +/- 1.8 years) or HD (n = 38, 22 males and 16 females, age 60.8 +/- 1.6 years). A group of 19 uraemic patients on conservative management served as the control. Serum concentrations of leptin, adiponectin and resistin were measured in all subjects. Information on vascular disease (cerebral vascular, peripheral vascular and heart disease) was obtained from a detailed medical history. RESULTS: PD patients showed significantly higher serum leptin concentrations [median (interquartile range), 28.7 (13.0-71.9) microg/l] than those found in patients on HD [9.7 (4.7-31.9) microg/l, P < 0.01] or in conservative management [5.9 (4.3-38.6) microg/l, P < 0.05]. Adiponectin concentrations were similar in the three groups of patients (mean +/- SEM, 48.0 +/- 4.5 mg/l in PD, 57.7 +/- 4.4 mg/l in HD, and 44.4 +/- 7.0 mg/l in controls, NS). Patients treated by both PD and HD exhibited resistin concentrations significantly higher than those found in controls (26.3 +/- 0.99 and 27.5 +/- 1.4 microg/l, respectively, vs. 17.3 +/- 1.0 microg/l, P < 0.001). Leptin concentrations were positively correlated with body mass index (BMI) (r = 0.287, P < 0.01) and adiponectin levels were negatively related to BMI (r = -0.416, P < 0.001) and the homeostatic model assessment (HOMA-R) index (r =-0.216, P < 0.05). Leptin, adiponectin and resistin levels in patients with previous vascular events were similar to those found in patients without these complications. Logistic regression analysis did not demonstrate any relationship between serum adipocytokine concentrations and the presence of vascular disease of any type. A significant relationship between resistin and heart disease [odds ratio (OR) 1.80 (1.03-3.15), P = 0.039] was found when analysing subgroups of patients. CONCLUSIONS: These data suggest that leptin levels are higher in PD patients, and resistin levels are higher in PD and HD patients in relation to patients on conservative management, whereas adiponectin concentrations are similar in the three groups. These results do not support the presence of a clinically relevant relationship between adipocytokines and previous episodes of vascular disease in the whole population or in patients classified in subgroups, with the only exception of a relationship between resistin levels and heart disease.

Growth hormone, IGF-I and its binding proteins (IGFBP-1 and -3) in adult uraemic patients undergoing peritoneal dialysis and haemodialysis.

OBJECTIVE: The GH/IGF axis is altered in chronic renal failure (CRF). CRF patients usually show normal or high serum concentrations of GH and IGF-I, whereas all IGF binding proteins (IGFBP-1 to -6), except IGFBP-5, considerably increase with declining renal function. The aims of the present study were to quantify serum concentrations of GH, IGF-I, IGFBP-1 and IGFBP-3 in a group of patients with CRF, and determine whether there were differences according to the type of dialysis, that is, peritoneal dialysis (PD) and haemodialysis (HD). DESIGN: A cross-sectional study in the setting of a dialysis unit of a general hospital. PATIENTS AND MEASUREMENTS: We studied 108 dialysis patients treated by PD (n = 54, 32 males and 22 females, mean age 61.0 +/- 1.4 years) or HD (n = 54, 31 males and 23 females, age 62.6 +/- 1.5 years). A group of 42 healthy subjects of similar age, sex and body mass index (BMI) served as the control group. Baseline serum concentrations of GH, insulin, IGF-I, IGFBP-1 and IGFBP-3 were measured in all patients and control subjects. RESULTS: Fasting serum concentrations of IGF-I and its binding proteins (IGFBP-1 and IGFBP-3) were significantly higher in dialysis patients than in subjects with normal renal function. IGF-I (248.9 +/- 23.4 vs. 205.5 +/- 15.5 micro g/l, NS), IGFBP-3 (5.6 +/- 0.4 vs. 5.5 +/- 0.2 mg/l, NS) and IGFBP-1 (36.1 +/- 5.9 vs. 44.1 +/- 6.5 micro g/l, NS) concentrations were similar in both groups of dialysis (PD vs. HD) patients. However, GH (2.3 +/- 0.3 vs. 1.1 +/- 0.1 micro g/l, P < 0.001) and insulin (40.4 +/- 4.5 vs. 30.1 +/- 3.1 micro U/ml, P < 0.05) levels were significantly higher in the PD group than in the HD group. Both groups of dialysis patients showed significantly higher levels of insulin than healthy subjects (14.7 +/- 1.9 micro U/ml, P < 0.0001 and P < 0.01 for PD and HD, respectively). In both groups of dialysis patients, IGF-I correlated inversely with IGFBP-1 (PD group r = -0.46, P = 0.0006; HD group r = -0.57, P = 0.0001) and directly with IGFBP-3 (PD group r = 0.44, P = 0.001; HD group r = 0.73, P = 0.001). No correlation between insulin and IGFBP-1 was found in any of the groups studied. CONCLUSIONS: These findings demonstrate that adult dialysis patients have elevated IGF-I, IGFBP-1 and IGFBP-3 serum concentrations compared with subjects with normal renal function. Only GH and insulin show statistically significant differences in relation to type of dialysis. Finally, the negative correlation between IGF-I and IGFBP-1 and the positive correlation between IGF-I and IGFBP-3 are maintained in both groups of adult dialysis patients.

Eating behavior disorders in uremia: a question of balance in appetite regulation.

Eating and appetite disorders are frequent complications of the uremic syndrome which contribute to malnutrition in dialysis patients. The data suggest that uremic anorexia may occur with or without abdominal and visceral fat accumulation despite a lower food intake. This form of obesity (i.e., with low food intake and malnutrition) is more common in dialysis patients than obesity with high food intake. This article reviews the current knowledge regarding mechanisms responsible for appetite regulation in normal conditions and in uremic patients. Anorexia in dialysis patients has been historically considered as a sign of uremic toxicity due to "inadequate" dialysis as judged by uncertain means ("middle molecule" accumulation, Kt/V, "peak-concentration hypothesis," and others). We propose the tryptophan-serotonin hypothesis, based on a uremia-induced disorder in patients' amino acid profile--low concentrations of large neutral and branched-chain amino acids with high tryptophan levels. A high rate of tryptophan transport across the blood-brain barrier increases the synthesis of serotonin, a major appetite inhibitor. Inflammation may also play a role in the genesis of anorexia and malnutrition. For example, silent infection with Helicobacter pylori may be a source of cytokines with cachectic action; its eradication improves appetite and nutrition. The evaluation of appetite should take into account cultural and social aspects. Uremic patients showed a universal trend to carbohydrate preference and red meat refusal compared to healthy people. In contrast, white meat was less problematic. Uremic patients also have a remarkable attraction for citrics and strong flavors in general. Eating preferences or refusals have been related to the predominance of some appetite peptide modulators. High levels of cholecystokinin (CCK) (a powerful anorexigen) are associated with early satiety for carbohydrates and neuropeptide Y (NPY) (an orexigen) with repeated food intake. Obesity and elevated body mass index often falsely suggest a good nutritional status. In uremic patients (a hyperinsulinemia state), disorders in the regulation of fat distribution (insulin, leptin, insulin-like growth factor [IGF]-1, fatty acids, and disorders in receptors for insulin, lipoprotein lipase, mitochondrial uncoupling protein-2, and beta 3 adrenoreceptors) may cause abdominal fat accumulation without an increase in appetite. Finally, appetite regulation in uremia is highly complex. Disorders in adipose tissue, gastrointestinal and neuropeptides, retained or hyperproduced inflammatory end products, and central nervous system changes may all play a role. Uremic anorexia may be explained by a hypothalamic hyperserotoninergic state derived from a high concentration of tryptophan and low branched-chain amino acids.