Background Trimethylamine N-oxide (TMAO), a metabolite from red meat and fish consumption, plays a role in promoting cardiovascular events. However, data regarding TMAO and its impact on clinical outcomes are inconclusive, possibly due to its undetermined dietary source. Objective We hypothesized circulating TMAO derived from fish intake might cause less harm compared to red meat source by examining the concomitant level of 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF), a known biomarker of fish intake, and investigated the association between TMAO, CMPF and outcomes. Design Patients were recruited from the European QUALity study on treatment in advanced CKD (EQUAL) among individuals ≥65 years whose eGFR had dropped for the first time to ≤20mL/min/1.73m2 during last 6 months. The association between TMAO, CMPF and outcomes including all-cause mortality and kidney replacement therapy (KRT) was assessed among 737 patients. Patients were further stratified by median cut-offs of TMAO and CMPF, suggesting high/low red meat and fish intake. Results During a median of 39 months’ follow-up, 232 patients died. Higher TMAO was independently associated with an increased risk of all-cause mortality (multivariable-hazard ratio (HR) 1.46, 95% confidence interval (CI) 1.17, 1.83). Higher CMPF was associated with a reduced risk of both all-cause mortality (HR 0.79, 95%CI 0.71, 0.89) and KRT (HR 0.80, 95%CI 0.71, 0.90), independent of TMAO and other clinically relevant confounders. In comparison to patients with low TMAO and CMPF, patients with low TMAO and high CMPF had reduced risk of all-cause mortality (adjusted HR 0.49, 95% CI 0.31, 0.73), whereas those with high TMAO and high CMPF showed no association across adjusted models. Conclusions High CMPF conferred an independent role in health benefits and might even counteract the unfavorable association between TMAO and outcomes. Whether higher circulating CMPF are due to fish consumption, and/or CMPF is a protective factor remains to be verified.

Background Patients with stage 4/5 chronic kidney disease (CKD) suffer from various symptoms. The retention of uremic solutes is thought to be associated with those symptoms. However, there are relatively few rigorous studies on the potential links between uremic toxins and symptoms in patients with CKD. Methods The EQUAL study is an ongoing observational cohort study of non-dialyzed patients with stage 4/5 CKD. EQUAL patients from Germany, Poland, Sweden, and the United Kingdom were included in the present study (n = 795). Data and symptoms self-report questionnaires were collected between April 2012 and September 2020. Baseline uric acid and parathyroid hormone and ten uremic toxins were quantified. We tested the association between uremic toxins and symptoms, and adjusted p-values for multiple testing. Results Symptoms were more frequent in women than in men with stage 4/5 CKD, while levels of various uremic toxins were higher in men. Only trimethylamine-N-oxide (positive association with fatigue), p-cresylsulfate with constipation, and 3 carboxy-4-methyl-5-propyl-2-furanpropionic acid (negative association with shortness of breath) demonstrated moderately strong associations with symptoms in adjusted analysis. The association of phenylacetylglutamine with shortness of breath was consistent in both sexes, although only reached statistical significance in the full population. By contrast, trimethylamine-N-oxide (fatigue) and p-cresyl sulfate and phenylacetylglutamine (constipation) were only associated with symptoms in men, who presented higher serum levels than women. Conclusion Only a limited number of toxins were associated with symptoms in persons with stage 4/5 CKD. Other uremic toxins, uremia related factors or psychosocial factors not yet explored might contribute to symptom burden.

BackgroundFructose acutely raises serum uric acid in normal subjects, but the effect in subjects with metabolic syndrome or subjects with chronic kidney disease is unknown. The aim of the study was to evaluate changes in serum uric acid during the fructose tolerance test in patients with chronic kidney disease, metabolic syndrome with comparison to healthy controls.MethodsStudies were performed in 36 subjects with obesity (body mass index >30) and metabolic syndrome, 14 patients with stage 3 chronic kidney disease, and 25 healthy volunteers. The fructose tolerance test was performed in each patient. The change in serum uric acid during the fructose challenge was correlated with baseline ambulatory blood pressure, serum uric acid, metabolic, and inflammatory markers, and target organ injury including carotid intima media thickness and renal resistive index (determined by Doppler).ResultsAbsolute serum uric acid values were highest in the chronic kidney disease group, followed by the metabolic syndrome and then healthy controls. Similar increases in serum uric acid in response to the fructose tolerance test was observed in all three groups, but the greatest percent rise was observed in healthy controls compared to the other two groups. No significant association was shown between the relative rise in uric acid and clinical or inflammatory parameters associated with kidney disease (albuminuria, eGFR) or metabolic syndrome.ConclusionsSubjects with chronic kidney disease and metabolic syndrome have higher absolute uric acid values following a fructose tolerance test, but show a relatively smaller percent increase in serum uric acid. Changes in serum uric acid during the fructose tolerance test did not correlate with changes in metabolic parameters, inflammatory mediators or with target organ injury. These studies suggest that acute changes in serum uric acid in response to fructose do not predict the metabolic phenotype or presence of inflammatory mediators in subjects with obesity, metabolic syndrome or chronic kidney disease.Trial registrationThe study was registered in ClinicalTrials.gov. Identifier : NCT01332526. www.register.clinicaltrials.gov/01332526Electronic supplementary materialThe online version of this article (doi:10.1186/s12882-015-0048-y) contains supplementary material, which is available to authorized users.

We present the case of a 64-year-old male patient in whom malignant phase of hypertension developed during dialysis therapy. Hypertension was resistant to pharmacological therapy with seven antihypertensive drugs and dialysis therapy with ultrafiltration. In this patient bilateral nephrectomy was performed as a rescue therapy. It led to better control of blood pressure and allowed to reduce the number and dosage of antihypertensive medications.