Cristina Martins

Predictive Value of Malnutrition Markers for Mortality in Peritoneal Dialysis Patients

INTRODUCTION Alterations in nutritional status have been described as important predictors of mortality in patients with chronic kidney disease (CKD). However, the association between multiple markers for nutritional status and the mortality rates of patients with CKD on peritoneal dialysis (PD) has not yet been illustrated in previously published data, particularly by using the new definition of protein energy wasting (PEW). OBJECTIVE To evaluate the predictive value of malnutrition markers for mortality rates, on the basis of the PEW definition, of PD patients. MATERIALS AND METHODS At the start of PD treatment, the nutritional status of 199 patients (mean age, 56 ± 13.3 years; 53% females) was evaluated. Body mass index (BMI), arm circumference, mid-arm muscle circumference, protein and caloric intake (by using a 3-day food record), and serum albumin were all recorded, as well as a subjective global assessment (SGA) and presence of PEW. Cut-off points were defined on the basis of the consensus of the International Society for Renal Nutrition and Metabolism (albumin, <3.8 g/dL; BMI, <23 kg/m(2); mid-arm muscle circumference, >10% in comparison with the 50th percentile for the reference population; protein intake, <0.8 g/kg/daily; caloric intake, <25 kcal/kg/daily). The data were obtained retrospectively between the years 2001 and 2008 on the basis of routine nutritional evaluation. Patients were monitored for fatal events from all possible causes. RESULT The mean BMI for the population was 26.6 ± 5.0 kg/m(2). A median protein intake of 0.94 (0.18 to 4.57) g/kg/daily was reported and 60.3% of the patients reported a protein intake of <0.8 g/kg/daily. With respect to caloric intake, 38.7% of the patients consumed <25 kcal/kg/daily. A median of 3.5 (1.4 to 5.3) g/dL for serum albumin was observed and 29.3% of the patients presented values of <3.8 g/dL. PEW was diagnosed in 17.5% of patients. In the univariate model, being of age >65 years (P = .002), cardiovascular disease (P < .001), diabetes mellitus (P = .02), SGA (P = .02), and albumin (P = .002), were all significant markers for mortality. The presence of patients aged >65 years (P = .02), with diabetes mellitus (P = .057), cardiovascular disease (P = .005), and albumin were considered as independent factors for mortality in this study. CONCLUSION SGA, albumin, and PEW were the only nutritional markers found to be associated with mortality in this cohort of PD patients. In the multivariate analysis, after adjusting for classic mortality risk factors, only patients with hypoalbuminemia were found to be at a high risk for mortality at follow-up. These results may be limited by the number of observations and a necessity for confirmation in larger prospective studies.

Association Between Body Mass Index and Body Fat in Chronic Kidney Disease Stages 3 to 5, Hemodialysis, and Peritoneal Dialysis Patients

OBJECTIVE Chronic kidney disease (CKD) patients may present with altered body composition. Body mass index (BMI) is a simple method for evaluating body fat mass (FM) in the general population. In CKD patients, there are few reports demonstrating the association between BMI and body composition. Our objective was to investigate the reliability of BMI as an indicator of FM in patients with CKD stages 3 to 5. METHODS Seventy-eight nondiabetic CKD patients (aged 48, SD +/- 12 years; 45% male) and 30 healthy control subjects (aged 46, SD +/- 12 years; 40% male), matched for age and sex, were evaluated. Chronic kidney disease patients were divided, according to K/DOQI guidelines, into 27 subjects at stages 3 to 4 (mean glomerular filtration rate of 43 +/- 12 mL/minute; age, 52 +/- 10 years), and 51 at stage 5: 25 in hemodialysis (HD) (aged 45, SD +/- 12 years; 44% male), and 26 in peritoneal dialysis (PD) (aged 49, SD +/- 13 years; 42% male). Body mass index was calculated as weight/height(2), and body composition was evaluated through dual-energy x-ray absorptiometry. RESULTS There was no difference in median BMI (kg/m(2)) among healthy control subjects (24.8; range, 19.2-34.1), CKD stages 3 to 4 (26.4; range, 20.4-37.6), HD patients (24.5; range, 19.4-35.7), and PD patients (24.5; range, 20.2-37.7; P > .05). Likewise, no significant difference was verified in median body FM (kg) among control subjects (18.8; range, 9.2-36.5), CKD stages 3 to 4 (21.2; range, 11.6-37.9), HD patients (17.1; range, 4.8-38.9), and PD patients (20.1; range, 6.5-41.5; P > .05). Moreover, a positive and significant correlation was found between BMI and FM (kg) in CKD stages 3 to 4 (Rho = 0.67, P = .0002), in HD patients (Rho = 0.67, P = .0002), in PD patients (Rho = 0.79, P < .0001), and in control subjects (Rho = 0.79, P < .0001). Although BMI and lean body mass (in kg) was significantly correlated in CKD stages 3 to 4 (Rho = 0.58, P = .001) and healthy control subjects (Rho = 0.30, P = .007), no significant correlation was found in HD patients (Rho = 0.19, P = .34) and in PD patients (Rho = 0.17, P = .38). CONCLUSIONS Body composition did not differ in patients with CKD stages 3 to 5, and between dialysis modalities. Although BMI was strongly and significantly correlated with body FM in CKD patients at stages 3 to 5, lean body mass was not. These findings suggest that BMI is a reliable indicator of body FM in this CKD population.

Associação entre gordura corporal, inflamação e estresse oxidativo na hemodiálise

INTRODUCTION The presence of malnutrition has been associated with inflammation and oxidative stress (OS) in patients on chronic hemodialysis (HD). OBJECTIVE To assess the association between nutritional status markers, such as body fat (BF), markers of inflammation and of OS in patients on HD. METHODS Cross-sectional study performed with 40 patients on HD. The nutritional status was evaluated by use of the modified subjective global assessment (SGAm), normalized total protein equivalent of nitrogen appearance (PNAn), serum albumin (Alb-s), body mass index (BMI), BF, and lean body mass (LBM). Inflammation and OS were assessed by use of high sensitivity protein C-reactive (HS-PCR), interleukin-6 (IL-6), advanced oxidation protein products (AOPP), 8-hydroxydeoxyguanosine (8OHdG), and pentosidine. RESULTS Some degree of malnutrition was observed in 37% of the patients assessed through SGAm. Median and variation of BF (kg) were 16.2 and 5.3-36.7, respectively. Regarding the markers of inflammation and of OS, a positive and significant correlation was observed between BMI and HS-PCR (R = 0.37; p = 0.02), BF and HS-PCR (R = 0.32; p = 0.04), and between HS-PCR and IL-6 (R = 0.51; p = 0.0007). A negative correlation was found between Alb-s and HS-PCR (R = -0.31; p = 0.05). Only in males HS-PCR related to BMI (R = 0.54; p = 0.01) and to BF (R = 0.52; p = 0.01). No association was found between markers of inflammation and of OS. CONCLUSION Markers of malnutrition and of overweight did not correlate with OS. The association of HS-PCR with BMI and BF only in the male sex may suggest differences in the inflammatory response between the sexes.

Association between hypokalemia, malnutrition and mortality in peritoneal dialysis patients

INTRODUCTION Hypokalemia is found in peritoneal dialysis (PD) patients. The problem may be severe and promote mortality. Several factors may trigger the hypokalemia in PD patients, such as preexisting malnutrition and the low protein and potassium food intake. OBJECTIVES To verify the prevalence of hypokalemia and its association with mortality, nutrition status, clinical, laboratory and electrocardiographic variables in PD patients. METHODS Serum K+ levels were evaluated retrospectively in PD patients. Hypokalemia was defined when the average of serum K+ was < 3.5 mEq/L in six consecutive measurements. Other available biochemical tests were also evaluated. Subjective Global Assessment (SGA) and body mass index (BMI) were used to assess the nutrition status. A questionnaire was applied to identify the most common symptoms and signals associated to hypokalemia. An electrocardiogram was performed. Demographic data, dialysis characteristics and survival rate were collected. RESULTS Hypokalemia was present in 15 out of 110 patients (13.6%). The survival rate was lower in the hypokalemic group (p = 0.002). Hypokalemia was only associated with serum levels of albumin and urea, and with the SGA results. CONCLUSION Low levels of serum potassium were associated to lower survival in PD patients and it seems to be related to malnutrition.

Calcium β-Hydroxy-β-Methylbutyrate

The binding capacity of calcium β-hydroxy-β-methylbutyrate (calcium HMB), compared to other binders, was investigated in an in vitro study. Fifty milli-equivalents of either calcium HMB, calcium acetate, calcium carbonate, aluminum hydroxide gel or non-gel aluminum hydroxide was added to a phosphate solution, titrated (HC1 or NaOH), shaken and centrifuged to four different pH levels at 37 °C (simulating the gastrointestinal milieu). The difference in phosphate concentration between that of the initial and that of the supernatant represented from the bound phosphate in the precipitate. After 4 h at a pH of 6 (representing the intestinal condition after a meal), the binding percentage was: calcium acetate = 95.6%, calcium HMB = 92.6%, calcium carbonate = 46.4%, aluminum hydroxide gel = 33.4% and non-gel aluminum hydroxide = 17.8%. There was no significant difference (p > 0.05) between calcium HMB and calcium acetate. These results suggest that calcium HMB is an efficient phosphate binder in vitro, which may predict its effective role in vivo.