Sarcopenia is prevalent in chronic hemodialysis patients. This prospective cohort study evaluated the impact of sarcopenia and its diagnostic criteria on hospitalization and mortality in 126 chronic hemodialysis patients. Skeletal muscle mass, handgrip strength (HGS), gait speed, and blood parameters were assessed. Sarcopenia was evaluated using the criteria of the European Working Group on Sarcopenia in Older People and the Taiwanese criteria for Sarcopenia. Muscle quality was defined as HGS divided by mid-arm muscle circumference. Prevalences of uremic sarcopenia were 8.7% and 13.5% according to Taiwanese and European criteria, respectively. Low HGS and gait speed were much more prevalent than low muscle mass. Within 3 years, 79 (62.7%) patients were hospitalized and 26 (20.6%) died. Low HGS and slow gait speed were associated with hospitalization and mortality, while sarcopenia was associated with mortality but not with hospitalization. Notably, in our patients without sarcopenia, close associations between increased hospitalization and mortality risk with low HGS and slow gait speed remained unchanged. In Cox proportional hazard analysis, muscle quality [hazard ratio (HR) = 0.42, 95% confidence interval (CI) = 0.19-0.93, p = 0.032] and serum creatinine (HR = 0.82, 95% CI = 0.71-0.95, p = 0.009) were independently associated with composite outcome of hospitalization or death. Muscle functionality and quality can predict hospitalization and overall survival in chronic hemodialysis patients, better than muscle mass.

Indoxyl sulfate (IS), a product metabolized from tryptophan, is negatively correlated with renal function and cardiovascular diseases in patients with chronic kidney disease (CKD). We investigated the association between serum IS levels and endothelial function in patients with CKD. Fasting blood samples were obtained from 110 patients with stages 3–5 CKD. The endothelial function, represented by vascular reactivity index (VRI), was measured non-invasively using digital thermal monitoring. Serum IS levels were determined using liquid chromatography–mass spectrometry. Twenty-one (19.1%), 36 (32.7%), and 53 (48.2%) patients had poor (VRI < 1.0), intermediate (1.0 ≤ VRI < 2.0), and good (VRI ≥ 2.0) vascular reactivity. By univariate linear regression analysis, a higher prevalence of smoking, advanced age, higher systolic, and diastolic blood pressure (DBP), elevated levels of serum phosphorus, blood urea nitrogen, creatinine, and IS were negatively correlated with VRI values, but estimated glomerular filtration rate negatively associated with VRI values. After being adjusted by using multivariate stepwise linear regression analysis, DBP and IS levels were significantly negatively associated with VRI values in CKD patients. We concluded that IS level associated inversely with VRI values and had a modulating role in endothelial function in patients with stages 3–5 CKD.

Sarcopenia, defined as low muscle mass and strength, is highly prevalent in patients undergoing chronic hemodialysis (HD). However, muscle function and muscle mass do not share the same clinical relevance. In fact, muscle strength was more closely associated with the risk of mortality in chronic HD patients than was muscle mass. Therefore, to identify the risk factors of muscle weakness is vital. Angiotensin II overexpression had been recognized to impair skeletal muscle strength. Accordingly, angiotensin II receptor blockers (ARBs) potentially possess a muscle protective effect. This cross-sectional study aimed to identify the factors associated with low muscle strength and to explore the relationship between ARB use and muscle strength in chronic HD patients. A total of 120 chronic HD patients, aged 63.3 ± 13.2 years, were included in this study. Basic characteristics, handgrip strength (HGS), body composition, and nutritional status were assessed, and blood samples for biochemical tests were obtained. We divided these participants into normal- and low HGS groups according to the consensus of the European Working Group on Sarcopenia in Older People (EWGSOP). We observed that 78 (65.0%) patients had low HGS. In our cohort, we found that height (r = 0.653; P < 0.001), weight (r = 0.496; P < 0.001), body mass index (r = 0.215; P = 0.020), skeletal muscle index (r = 0.562; P < 0.001), albumin (r = 0.197; P = 0.032), and serum creatinine (r = 0.544; P < 0.001) were positively and age (r = − 0.506; P < 0.001), subjective global assessment (SGA) score (r = − 0.392; P < 0.001), fractional clearance index for urea (Kt/V) (r = − 0.404; P < 0.001) and urea reduction ratio (URR) (r = − 0.459; P < 0.001) were negatively correlated with HGS. According to our analysis, age (Odds ratio, OR = 1.11, 95% confidence interval, 95% CI = 1.05–1.17, P < 0.001), HD duration (OR = 1.01, 95% CI = 1.00–1.02, P = 0.010), diabetes (OR = 13.33, 95% CI = 3.45–51.53, P < 0.001), Kt/V (OR = 1.61, 95% CI = 1.06–2.46, P = 0.027), and SGA score (OR = 1.19, 95% CI = 1.03–1.38, P = 0.017) were regarded as independent predictors of low HGS. In contrast, ARB use (OR = 0.25, 95% CI = 0.07–0.93, P = 0.039) was independently associated with preserved HGS in chronic HD patients, after adjustment for multiple confounding factors. Our study is the first report in chronic HD patients to indicate a potentially protective effect of ARB on muscle strength. However, further longitudinal follow-up and intervention studies are needed to confirm this finding.

Arterial stiffness (AS) has an important impact on the outcomes of patients on hemodialysis (HD), and p-cresyl sulfate (PC) can mediate the process of vascular damage. We aimed to investigate the relationship between carotid–femoral pulse wave velocity (cfPWV) and the level of PCs in HD patients. Serum PCs were quantified using liquid chromatography mass spectrometry. Patients who were on standard HD for more than 3 months were enrolled and categorized according to the cfPWV into the high AS (>10 m/s) and control (≤10 m/s) groups. Forty-nine (41.5%) patients belonged to the high AS group and had a higher incidence of diabetes mellitus (DM) and increased systolic blood pressure, serum C-reactive protein, and PC levels but had lower creatinine, compared with those in the control group. In HD patients, the risk for developing high AS increased in the presence of DM (OR 4.147, 95% confidence interval (CI) 1.497–11.491) and high PCs (OR 1.067, 95% CI 1.002–1.136). Having DM (r = 0.446) and high PC level (r = 0.174) were positively associated with cfPWV. The most optimal cutoff value of PC for predicting AS was 18.99 mg/L (area under the curve 0.661, 95% CI 0.568–0.746). We concluded that DM and PCs were promising predictors of high AS in patients on maintenance HD.

Circulating malondialdehyde-modified low-density lipoprotein (MDA-LDL) acts as a marker of oxidative stress and is associated with atherosclerotic cardiovascular disease. The relationship between serum MDA-LDL levels and aortic stiffness (AS) in patients with hemodialysis (HD) was evaluated. There were 155 HD patients enrolled in this study. Carotid-femoral pulse wave velocity (cfPWV) was measured by a validated tonometry system. Patients with cfPWV >10 m/s were used to define the AS group, while those with values of ≤10 m/s were regarded as the control group. Serum MDA-LDL levels were measured using a commercial enzyme-linked immunosorbent assay. Sixty-eight patients (43.9%) who were defined as AS sufferers, and were older, had a higher percentage of diabetes and hypertension and higher systolic blood pressure and serum MDA-LDL level compared to subjects in the control group. After adjusting for factors significantly associated with AS by multivariable logistic regression analysis, it was revealed that serum MDA-LDL levels, diabetes, and hypertension were independent predictors of AS in HD patients. Multivariable forward stepwise linear regression analysis also showed that a logarithmically transformed MDA-LDL level was significantly correlated with cfPWV values in HD patients. In HD patients, a high serum MDA-LDL level was positively associated with cfPWV values and was a significant predictor of the development of high AS.