Urinary β-trace protein: A unique biomarker to screen early glomerular filtration rate impairment

The screening for chronic kidney disease (CKD) patients needs the measurement of serum markers like creatinine. Our previous results indicated that urinary excretion of β-trace protein (BTP), a low-molecular-weight protein (23-29 kDa), is increased in CKD patients from stage 2. The aim of this study was to assess the major determinants of urinary excretion of BTP and to evaluate its feasibility as noninvasive marker of glomerular filtration rate (GFR) impairment.We studied 355 CKD patients (198 males), aged 15 to 83 years, in stable clinical conditions, classified in the different stages of CKD on the basis of GFR (renal clearance of Tc-diethylenetriamine penta-acetic acid). At the same time, we measured serum and urinary creatinine and BTP, and urinary albumin. Urinary excretion of BTP and albumin was expressed as mg/g urinary creatinine. Fractional clearance of BTP was calculated as the ratio of BTP clearance to creatinine clearance (%).Urinary excretion of BTP is mainly determined by its serum concentration and by the level of GFR, and to a lower extent by urinary albumin excretion. In fact, urinary BTP (U-BTP) and fractional clearance of BTP progressively and significantly increased along with the reduction of GFR and the concurrent rise in serum BTP (S-BTP). The relationship of U-BTP with GFR was very similar to that of S-BTP with GFR: U-BTP mirrors S-BTP. The accuracy of U-BTP to screen patients with GFR <90 mL/min/1.73 m was good (area under the curve 0.833), its sensitivity was 76.9%, specificity 80%, and positive predictive value 84.9%. Sensitivity of U-BTP was quite similar to that of S-BTP and serum creatinine.The major determinants of urinary excretion of BTP are S-BTP and GFR. U-BTP may be a suitable noninvasive marker to screen the general population for detection of GFR <90 mL/min/1.73 m

Standard di professione del dietista in nefrologia: realtà a confronto

La terapia dietetica svolge un ruolo fondamentale nel trattamento della malattia renale cronica (CKD): previene e corregge le complicanze metaboliche, garantisce il mantenimento o il raggiungimento di uno stato nutrizionale soddisfacente e, nella fase conservativa, ritarda l'inizio della terapia sostitutiva. Molte sono le evidenze che attestano che il trattamento nutrizionale effettuato da un dietista esperto migliora la qualità di vita del paziente con insufficienza renale cronica, aumenta l'eff -cacia della terapia dietetica e riduce i costi assistenziali. Negli Stati Uniti sono stati definiti i parametri che identificano il dietista esperto nella gestione della terapia nutrizionale nel paziente nefropatico e sono state individuate tre categorie in base al grado di formazione e competenza acquisita. Nei Paesi dell'Unione Europea la formazione dei dietisti è molto eterogenea tanto da rendere difficile una comparazione con la realtà americana. L'European Federation of the Association of Dietitians negli ultimi anni ha comunque definito gli standard accademici e professionali dei dietisti individuando quattro ruoli di competenza ed i relativi indicatori di performance. In Italia l'Associazione Nazionale Dietisti ha definito le posizioni dell'associazione in merito alla pratica professionale del dietista nel trattamento delle malattie renali e la Società Italiana di Nefrologia, nell'ambito del progetto di certificazione della qualità del percorso di cura della CKD, ha delineato il profilo del dietista che lavora in nefrologia ma non sono stati definiti standard accademici e professionali specifici. È auspicabile che dietisti esperti in nefrologia e nefrologi collaborino nel definire protocolli relativi a standard che il dietista operante in ambito nefrologico dovrebbe raggiungere in modo da garantire maggiore competenza professionale e una omogeneità di trattamento su tutto il territorio nazionale

Effective and timely evaluation of pulmonary congestion: Qualitative comparison between lung ultrasound and thoracic bioelectrical impedance in maintenance hemodialysis patients

The assessment of pulmonary congestion in maintenance hemodialysis (MHD) patients is challenging. Bioelectrical impedance analysis (BIA) can estimate body water compartments. Natriuretic peptides are markers of hemodynamic stress, neurohormonal activation and extracellular volume overload. Lung ultrasound (LUS) has been proposed for the non-invasive estimation of extravascular lung water through B-lines assessment. Up to now, no study evaluated the correlation between B-lines, segmental thoracic BIA, and natriuretic peptides in MHD patients. The aims of this study were: (1) To validate LUS as a tool for an effective and timely evaluation of pulmonary congestion in MHD patients, in comparison with segmental thoracic BIA, and with natriuretic peptides; (2) To compare a comprehensive whole chest ultrasound scanning with a simplified and timely scanning scheme limited to the lateral chest regions.Thirty-one MHD adult patients were examined. LUS, total body and thoracic BIA, and natriuretic peptides were performed immediately before and after a mid-week dialysis session. The number of B-lines assessed by LUS was compared with total body and thoracic impedance data and with natriuretic peptides.Pre-HD B-lines ranged 0-147 (mean 31) and decreased significantly post-HD (mean 16, P < 0.001). A significant correlation was found between the number of B-lines and extra-cellular water index (ECWI, r = 0.45, P < 0.001), with thoracic impedance (r = 0.30, P < 0.05), and with BNP (r = 0.57, P < 0.01). The dynamic changes in B-lines correlated better with thoracic impedance than with total body impedance, and correlated with extra-cellular but not with intra-cellular water index. The correlation between B-lines and ECWI was similar when LUS was limited to the lateral chest regions or performed on the whole chest. Multivariate analysis showed that only segmental thoracic impedance was an independent predictor of residual pulmonary congestion.The dynamic changes in B-lines after hemodialysis are correlated to the changes in total body and extra-cellular water, and particularly to lung fluids removal. B-line assessment in MHD patients is highly feasible with a simplified and timely scanning scheme limited to the lateral chest regions. These premises make B-lines a promising biomarker for a bedside assessment of pulmonary congestion in MHD patients

Valutazione dello stato nutrizionale in corso di insufficienza renale acuta mediante ecografia del muscolo quadricipite femorale.

Il danno renale acuto (AKI, Acute Kidney Injury) è una delle complicanze più gravi osservate nei pazienti ospedalizzati, essendo in grado di determinare un significativo aumento della mortalità e delle complicanze a breve e a lungo termine. L’incidenza di AKI è elevata soprattutto in ambito intensivo (UTI, Unità di Terapia Intensiva) dove può raggiungere il 30% di incidenza, e spesso si associa ad insufficienza multiorgano. I pazienti critici con AKI hanno un elevato rischio di sviluppare uno stato di deplezione calorico proteica (PEW, Protein Energy Wasting), determinata sia dalle patologie acute in atto, dall'immobilizzazione e dal ridotto intake di nutrienti, sia da fattori tipici dell'AKI, come la presenza di acidosi metabolica e la necessità di terapia sostitutiva della funzione renale (RRT, renal replacement therapy). La presenza di PEW può quindi concorrere a determinare un ulteriore aumento del già elevato tasso di mortalità. La precoce identificazione dei pazienti a rischio di PEW e la rapida diagnosi di essa potrebbero consentire interventi terapeutico-nutrizionali adeguati e precoci. La riduzione della massa muscolare rappresenta uno dei criteri fondamentali per la diagnosi di PEW. Nel paziente con AKI ciò è reso particolarmente difficoltoso dal fatto che i metodi classici per la valutazione della composizione corporea risultano influenzati dall'alterato bilancio dei fluidi tipico di questi pazienti. Studi recenti svolti su pazienti critici, suggeriscono come l’ecografia muscolare possa rappresentare uno strumento efficace in grado di consentire la valutazione ed il monitoraggio della massa muscolare, in particolare a livello del muscolo quadricipite femorale. L’ecografia rappresenta infatti una metodica semplice, ripetibile, non invasiva e priva di radiazioni ionizzanti. Nessuno studio presente in letteratura ha finora valutato la fattibilità dell’ecografia muscolare nei pazienti critici affetti da AKI e sottoposti a RRT. Per tale motivo è stato disegnato uno studio pilota prospettico, effettuato presso la Terapia Intensiva della Clinica ed Immunologia Medica dell'Azienda Ospedaliero-Universitaria di Parma, con i seguenti obiettivi: 1) valutazione di eventuali modifiche dello spessore muscolare pre e post dialisi a livello del muscolo retto femorale e vasto intermedio nel punto medio e a livello dei 2/3 inferiori della coscia; 2) riproducibilità intra ed interoperatore della metodica ecografica; 3) confronto dell’ecografia muscolare con la bioimpedenziometria (BIA) multifrequenza e l’antropometria; 4) monitoraggio dello spessore muscolare durante la degenza in UTI; 5) confronto dello spessore muscolare dei pazienti con AKI rispetto a soggetti sani e a pazienti ospedalizzati con funzione renale normale. I risultati dello studio, effettuato su 19 pazienti con AKI e necessità di RRT, hanno mostrato che 1) lo spessore muscolare non subisce modifiche statisticamente significative a livello di 3 siti muscolari su 4, anche a fronte di variazioni di peso intradialitiche fino a 3 kg ottenute in tempi brevi; la stratificazione delle RRT in base al calo ponderale ottenuto mostra una tendenza alla riduzione dello spessore muscolare nel post dialisi (1.44 vs 1.42 cm, p= 0.0593) nel caso di trattamenti dialitici con calo più rilevante (1.89 ± 0.7 kg); 2) l’ICC (coefficiente di correlazione intraclasse) presenta valori più elevati (> 0.97) per la riproducibilità intraoperatore piuttosto che interoperatore (>0.88); 3) è presente una buona correlazione dello spessore muscolare con la lean body mass (LBM) e la body cell mass (BCM) stimate con la BIA, con dati più significativi nel post dialisi (LBM: r=0.51, p=0.01; BCM: r=0.55, p=0.005). È presente anche una correlazione con i comuni parametri antropometrici, in particolare con la circonferenza del braccio, con correlazione migliore nel post dialisi (r=0.52, p=0.0004). 4) Lo spessore del muscolo retto femorale subisce una riduzione dell’11%, statisticamente significativa, durante la degenza in UTI (1.41 vs 1.26 cm, p=0.0002); 5) al momento della prima misurazione, i pazienti con AKI hanno uno spessore muscolare inferiore, anche se non statisticamente significativo, rispetto ai controlli sani e ai pazienti ospedalizzati. Durante la degenza, le differenze tendono ad accentuarsi e dopo almeno 5 giorni, si evidenzia una differenza statisticamente significativa nella maggioranza dei siti muscolari. Nei pazienti critici affetti da AKI e sottoposti a RRT, l’ecografia muscolare ha quindi evidenziato una marcata deplezione della massa magra misurata a livello del muscolo quadricipite femorale durante la degenza in UTI, di entità sovrapponibile a quanto riportato in Letteratura in riferimento ai pazienti critici senza danno renale. La terapia dialitica, determinando una rapida variazione di volume, potrebbe determinare un minimo effetto di riduzione dello spessore muscolare non legato a fattori nutrizionali: è quindi consigliabile standardizzare la metodica, e in riferimento alla dialisi, eseguire l’esame nelle stesse condizioni temporali. Concludendo, l’ecografia muscolare eseguita sempre dallo stesso operatore, rappresenta uno strumento affidabile e sensibile nel riconoscere le variazioni dello spessore muscolare in corso di AKI in terapia intensiva. Si rendono comunque necessari ulteriori studi su popolazioni più ampie per definire in maniera migliore il ruolo dell’ecografia muscolare come parametro nutrizionale nei pazienti critici con AKI

[Hyponatremia: from guidelines to clinical practice]

The publication, within a short time interval, of a consensus statement on the pathophysiology, diagnosis and treatment of hyponatremia by a panel of experts mainly from the US and of the European Guidelines on the same topic has marked an important step towards reducing the differences in the treatment of this frequent, and potentially fatal, electrolyte disorder. Within this framework, the European Society of Intensive Care Medicine (ESICM), the European Society of Endocrinology (ESE), and the European Dialysis and Transplantation Association-European Renal Association, represented by the European Renal Best Practice (ERBP), have developed these Guidelines for clinical practice, that are focused mainly on the diagnosis and the treatment of hyponatremia. In fact, they are the result of a tight collaboration between the three scientific societies involving those specialists with an elective interest for this electrolyte disorder. In addition to a rigorous methodological approach, a choice was made to provide a document focused on clinically relevant outcomes and useful for everyday practice. With respect to the original paper, this version of the Guidelines has been shortened and translated with a special view to the recommendations concerning the diagnosis and treatment of hyponatremia. It is preceded by an introduction underscoring the main targets of non-pharmacological treatment in acute severely symptomatic cases, specifically as regards the rate of correction of hyponatremia; subsequently, potential explanations for the discrepancies between the European Guidelines and the consensus statement by US experts concerning the use of vaptans are briefly discussed; the rationale and practical limitations in the clinical use of urea are analyzed in more detail

Reliability of bedside ultrasound for measurement of quadriceps muscle thickness in critically ill patients with acute kidney injury

Main problem: In patients with Acute Kidney Injury there is a lack of nutritional variables that can assess nutritional status, more specifically lean body mass (LBM) and skeletal muscle mass, at the individual level. In this clinical setting, ultrasound (US)) of the quadriceps femoris could represent a widely available, non-invasive, affordable, and reliable tool to evaluate skeletal muscle. Methods: We performed a cross-sectional observational study in adult critically ill patients with KDIGO stage 3 AKI on dialysis. Quadriceps rectus femoris and vastus intermedius thickness were measured by two assessors. Intra- and interobserver reliability was evaluated using the intraclass correlation coefficient (ICC). The same US measures were obtained before and after dialysis. Results: We enrolled 34 patients, 22 (65%) were male and the mean APACHE II score was 22.7 (±5.6). In the intraobserver reliability study, assessor 1 performed 288 paired measurements and assessor 2 performed 430 paired measurements in 34 patients, with an ICC equal to 0.99 and 1.00, respectively. There were 238 paired measurements (34 patients) in the interobserver reliability study, with an ICC = 0.92. No difference was found in the measurements obtained before and after dialysis (11.5 (4.2) vs 11.4 (4.1) mm, P = 0.2498), independently from acute body weight changes due to fluid removal. Conclusion: In patients with AKI, US of quadriceps femoris could represent a simple, accurate, and non-invasive method to evaluate quantitative changes in skeletal muscle

Dietary protein restriction for renal patients: don't forget protein-free foods

The treatment of chronic kidney disease (CKD) consists of pharmacological, nutritional, and psychological-social approaches. The dietary therapy of CKD, namely a low-protein low-phosphorus diet, plays a crucial role in contributing to delay the onset of end-stage renal disease (ESRD) and to protect cardiovascular and nutritional status. The protein-free food products represent a very important tool for the implementation of a low-protein diet to ensure adequate energy supply, reducing the production of nitrogenous waste products

Deplezione proteico-energetica e supplementazione nutrizionale nei pazienti in emodialisi cronica [Protein-energy wasting and nutritional supplementation in chronic hemodialysis]

Protein Energy Wasting (PEW) is a pathological condition characterized by a progressive reduction of protein and energy stores. PEW has a high prevalence among patients with CKD/ESRD (Chronic Kidney Disease/End Stage Renal Disease) and is closely associated with adverse clinical outcomes and increased rate of hospitalization, complications and mortality. The multifactorial pathogenesis of PEW is complex. A key role is played both by the reduced intake of nutrients and the condition of hypercatabolism/reduced anabolism typical of renal patients. The approach to prevent or treat PEW has several milestones such as reduction of potential risk factors, improvement in lifestyle and correction of any factor related to dialysis. It also needs a periodic assessment of nutritional status by using biochemical markers, body and muscle mass variables, nutritional scores and instrumental methods, aiming for an early diagnosis. In case of reduced protein and energy intake, the administration of nutrients during dialysis, or the use of oral supplements specific for renal patients are the first nutritional interventions recommended. In fact, oral nutritional supplementation represents the most effective nutritional approach to PEW prevention and treatment. It is simple and safe and it has a positive impact on quality of life and survival of haemodialysis patients. In the case of failure of oral supplementation, nutritional support should be enhanced by using intradialytic parenteral nutrition (IDPN). If the patient has difficulty in swallowing or IDPN is insufficient, total enteral nutrition should be considered

[Protein-energy wasting and nutritional supplementation in chronic hemodialysis]

Protein Energy Wasting (PEW) is a pathological condition characterized by a progressive reduction of protein and energy stores. PEW has a high prevalence among patients with CKD/ESRD (Chronic Kidney Disease/End Stage Renal Disease) and is closely associated with adverse clinical outcomes and increased rate of hospitalization, complications and mortality. The multifactorial pathogenesis of PEW is complex. A key role is played both by the reduced intake of nutrients and the condition of hypercatabolism/reduced anabolism typical of renal patients. The approach to prevent or treat PEW has several milestones such as reduction of potential risk factors, improvement in lifestyle and correction of any factor related to dialysis. It also needs a periodic assessment of nutritional status by using biochemical markers, body and muscle mass variables, nutritional scores and instrumental methods, aiming for an early diagnosis. In case of reduced protein and energy intake, the administration of nutrients during dialysis, or the use of oral supplements specific for renal patients are the first nutritional interventions recommended. In fact, oral nutritional supplementation represents the most effective nutritional approach to PEW prevention and treatment. It is simple and safe and it has a positive impact on quality of life and survival of haemodialysis patients. In the case of failure of oral supplementation, nutritional support should be enhanced by using intradialytic parenteral nutrition (IDPN). If the patient has difficulty in swallowing or IDPN is insufficient, total enteral nutrition should be considered