Validation of a Phosphorus Food Frequency Questionnaire in Patients with Kidney Failure Undertaking Dialysis.

Nutritional guidelines recommended limiting dietary phosphorus as part of phosphorus management in patients with kidney failure. Currently, there is no validated phosphorus food frequency questionnaire (P-FFQ) to easily capture this nutrient intake. An FFQ of this type would facilitate efficient screening of dietary sources of phosphorus and assist in developing a patient-centered treatment plan. The objectives of this study were to develop and validate a P-FFQ by comparing it with the 24 hr multi-pass recall. Fifty participants (66% male, age 70 ± 13.3 years) with kidney failure undertaking dialysis were recruited from hospital nephrology outpatient departments. All participants completed the P-FFQ and 24 hr multi-pass recalls with assistance from a renal dietitian and then analysed using nutrient analysis software. Bland-Altman analyses were used to determine the agreement between P-FFQ and mean phosphorus intake from three 24 hr multi-pass recalls. Mean phosphorous intake was 1262 ± 400 mg as determined by the 24 hr multi pass recalls and 1220 ± 348 mg as determined by the P-FFQ. There was a moderate correlation between the P-FFQ and 24 hr multi pass recall (r = 0.62, p = 0.37) with a mean difference of 42 mg (95% limits of agreement: 685 mg; -601 mg, p = 0.373) between the two methods. The precision of the P-FFQ was 3.33%, indicating suitability as an alternative to the 24 hr multi pass recall technique. These findings indicate that the P-FFQ is a valid, accurate, and precise tool for assessing sources of dietary phosphorus in people with kidney failure undertaking dialysis and could be used as a tool to help identify potentially problematic areas of dietary intake in those who may have a high serum phosphate.

The Effects of OMEGA-3 Fatty Acid Supplementation Upon Interleukin-12 and Interleukin-18 in Chronic Kidney Disease Patients.

OBJECTIVE(S): Cardiovascular disease (CVD) remains a leading cause of mortality in chronic kidney disease (CKD) patients. Interventions targeting traditional risk factors have largely proven ineffective in CKD patients in part because of the increased role of nontraditional risk factors such as chronic inflammation. Omega-3 fatty acids (ω3FA) are inexpensive and safe natural agents, which target inflammation and have potential cardioprotective benefits. The aim of the study was to determine the effects of ω3FA supplementation upon serum interleukin (IL)-12, IL-18, and highly sensitive C-reactive protein (hsCRP) in patients with Stage 3-4 CKD. METHODS: We performed a post-hoc analysis of a randomized placebo-controlled trial in 73 nondiabetic CKD patients to determine the effects of ω3FA supplementation (4 g daily for 8 weeks) upon serum levels of IL-12, IL-18, and hsCRP. RESULTS: There were no preintervention differences in IL-12, IL-18, or hsCRP between treatment groups. Postintervention levels of IL-12, IL-18, and hsCRP were similar between the treatment groups. However, IL-12 and IL-18 increased in both treatment groups over the intervention period, whereas hsCRP remained unchanged. The magnitude of increase in serum IL-18 (ΔIL-18) was significantly less in participants in the ω3FA treatment group compared to placebo (P = .047). CONCLUSION(S): This study has shown that 4 g daily ω3FA supplementation may lower serum IL-18 levels in patients with moderate CKD. Although there were no apparent effects on several other markers of inflammation, this study provides evidence for a specific effect of ω3FA on inflammatory pathways.

Renal function and 25-hydroxyvitamin D concentrations predict parathyroid hormone levels in renal transplant patients.

BACKGROUND: Recent guidelines suggest supplementation with ergocalciferol (vitamin D(2)) in chronic kidney disease stages 3 and 4 patients with elevated parathyroid hormone (PTH) levels and 25-hydroxyvitamin D (25OHD) levels <75 nmol/l. These guidelines are also applied to renal transplant patients. However, the prevalence rates of 25OHD deficiency and its association with PTH levels in renal transplant populations have not been extensively examined. We aimed to document the prevalence rates of 25OHD deficiency [defined by serum levels <40 nmol/l (<16 ng/ml)] and insufficiency [<75 nmol/l (<30 ng/ml)] in a single renal transplant centre, and examine its relationship with PTH levels. METHODS: Serum 25OHD and PTH concentrations were measured in 419 transplant patients attending a single renal transplant clinic over a 4-month period. Demographic and biochemical data were also collected, including serum creatinine, calcium, phosphate and albumin. Simple and multiple linear regression analysis were performed. RESULTS: In 27.3% of the patients, 25OHD deficiency was present, and 75.5% had insufficiency. On univariate analysis, 25OHD, serum albumin and estimated glomerular filtration rate (eGFR) were significantly associated with PTH levels (P < 0.0001, P = 0.004 and P < 0.0001, respectively). Multiple linear regression demonstrated that only 25OHD, eGFR and serum phosphate were significantly predictive of PTH levels (R(2) = 0.19, P < 0.0001). In this model, a 75 nmol/l increase in 25OHD will only result in a maximal reduction in PTH of 2.0 pmol/l. CONCLUSIONS: We conclude that 25OHD deficiency and insufficiency are common in renal transplant patients and may exacerbate secondary hyperparathyroidism. However, 25OHD, eGFR and phosphate only account for 19% of the variability in PTH levels. In addition, even a large increase in serum 25OHD levels is likely to result in only a small reduction in PTH. Therefore, alternative approaches to managing hyperparathyroidism in renal transplant recipients rather than supplementation with ergocalciferol are warranted.

Oral nutritional supplementation increases caloric and protein intake in peritoneal dialysis patients.

BACKGROUND: Malnutrition is highly prevalent in peritoneal dialysis (PD) patients and is associated with a poor prognosis. Attempts to improve nutritional status with enteral supplements have yielded poor results. METHODS: We performed a crossover-design trial on 13 PD patients to investigate whether these patients reduce their food intake after drinking oral nutritional supplements. Patients attended three visits in which they were administered a standard oral nutritional supplement either 2 hours or 30 minutes before lunch or a placebo drink 30 minutes before lunch. Lunch was provided as a self-select buffet-style meal, and food intake was measured. Total intake was calculated by adding the nutritional content of the oral supplement. RESULTS: Patients showed poor food intake, with mean values equaling only 18% of the recommended daily intake for calories and 34% for protein. Drinking the supplement 2 hours before lunch resulted in a significant increase compared with the placebo visit in total caloric (430 to 843 kcal; P < 0.001) and protein intake (27.6 to 41.3 g; P = 0.006). No significant difference in total intake was detected between drinking the supplement 2 hours versus 30 minutes before lunch. CONCLUSION: These results indicate that oral nutritional supplements administered before a meal may significantly increase caloric and protein intakes of PD patients.