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Abstract Creatine is a natural nitrogenous organic acid that is integral to energy metabolism and crucial for proper cell functioning. The kidneys are involved in the first step of creatine production. With kidney transplantation being the gold-standard treatment for end-stage kidney disease, kidney transplant recipients (KTR) may be at risk of impaired creatine synthesis. We aimed to compare creatine homeostasis between KTR and controls. Plasma and urine concentrations of arginine, glycine, guanidinoacetate, creatine and creatinine were measured in 553 KTR and 168 healthy controls. Creatine intake was assessed using food frequency questionnaires. Iothalamate-measured GFR data were available in subsets of 157 KTR and 167 controls. KTR and controls had comparable body weight, height and creatine intake (all P > 0.05). However, the total creatine pool was 14% lower in KTR as compared to controls (651 ± 178 vs. 753 ± 239 mmol, P

Rationale & Objective: Older people with progressive chronic kidney disease (CKD) have complex health care needs. Geriatric evaluation preceding decision making for kidney replacement is recommended in guidelines, but implementation is lacking in routine care. We aimed to evaluate implementation of geriatric assessment in CKD care. Study Design: Mixed methods implementation study. Setting & Participants: Dutch nephrology centers were approached for implementation of geriatric assessment in patients aged ≥70 years and with an estimated glomerular filtration rate of ≤20 mL/min/1.73 m2. Quality Improvement Activities/Exposure: We implemented a consensus-based nephrology-tailored geriatric assessment: a patient questionnaire and professionally administered test set comprising 16 instruments covering functional, cognitive, psychosocial, and somatic domains and patient-reported outcome measures. Outcomes: We aimed for implementation in 10 centers and 200 patients. Implementation was evaluated by (i) perceived enablers and barriers of implementation, including integration in work routines (Normalization Measure Development Tool) and (ii) relevance of the instruments to routine care for the target population. Analytical Approach: Variations in implementation practices were described based on field notes. The postimplementation survey among health care professionals was analyzed descriptively, using an explanatory qualitative approach for open-ended questions. Results: Geriatric assessment was implemented in 10 centers among 191 patients. Survey respondents (n = 71, 88% response rate) identified determinants that facilitated implementation, ie, multidisciplinary collaboration (with geriatricians) -meetings and reports and execution of assessments by nurses. Barriers to implementation were patient illiteracy or language barrier, time constraints, and patient burden. Professionals considered geriatric assessment sufficiently integrated into work routines (mean, 6.7/10 ± 2.0 [SD]) but also subject to improvement. Likewise, the relevance of geriatric assessment for routine care was scored as 7.8/10 ± 1.2. The Clinical Frailty Score and Montreal Cognitive Assessment were perceived as the most relevant instruments. Limitations: Selection bias of interventions’ early adopters may limit generalizability. Conclusions: Geriatric assessment could successfully be integrated in CKD care and was perceived relevant to health care professionals. Plain-Language Summary: The number of older persons with kidney failure is increasing, many of whom have cognitive decline or are dependent on others for daily life tasks. These problems are often overlooked but relevant for future treatment choices, and they affect quality of life. We asked 10 health care centers to use tests and questionnaires to identify these issues, thus being able to offer additional support. We learned that it is possible to use these assessments in practice and that professionals found them relevant. Collaboration with geriatric departments was perceived valuable. However, there are also challenges, such as not having enough time and personnel and burden to patients. Understanding these possibilities and challenges is crucial for improving care for older patients with kidney failure.

Copeptin is increasingly used in epidemiological studies as a substitute for vasopressin. The effect of renal function per se on copeptin and vasopressin concentrations as well as their ratio have, however, not been well described. Methods: Copeptin and vasopressin levels were measured in 127 patients with various stages of chronic kidney disease, including 42 hemodialysis patients and 16 healthy participants in this observational study. Linear (segmental) regression analyses were performed to assess the association between renal function and copeptin, vasopressin and the C/V ratio. In addition, clearance of copeptin and vasopressin by hemodialysis was calculated. Results: Both copeptin and vasopressin levels were higher when renal function was lower, and both showed associations with plasma osmolality. The C/V ratio was stable across renal function in subjects with an eGFR >28 ml/min per 1.73 m2. In contrast, the C/V ratio increased with worsening renal function in patients with eGFR ≤28 ml/min per 1.73 m2. During hemodialysis, the initial decrease in vasopressin levels was greater compared with copeptin and, consequently, the C/V ratio increased. This was, at least in part, explained by a greater dialytic clearance of vasopressin compared with copeptin. Discussion: Our data indicate that copeptin is a reliable substitute for vasopressin in subjects with an eGFR >28 ml/min per 1.73 m2, whereas at an eGFR ≤28 ml/min per 1.73 m2, that is, CKD stages 4 and 5, a correction for renal function is required in epidemiological studies that use copeptin as a marker for vasopressin. Intradialytic copeptin levels do not adequately reflect vasopressin levels because vasopressin clearance by hemodialysis is higher than that of copeptin.

Background/Aims: Higher interdialytic weight gain (IDWG) is associated with higher predialysis blood pressure and increased mortality. IDWG is also increasingly being recognized as an indicator of nutritional status. We studied in detail the associations of various patient factors and nutritional parameters with IDWG. Methods: We collected data during one week for IDWG and hemodynamic parameters in 138 prevalent adult haemodialysis patients on a thrice-weekly haemodialysis schedule. A multivariate linear regression analysis was employed to identify factors that are associated with IDWG. Results: The mean (±SD) age was 62.5 (±18.2) years, 36% were female, 36% had diuresis, and 23% had diabetes. Patients in the highest IDWG tertile were significantly younger, more frequently male, and had a significantly higher subjective global assessment score (SGA). A higher IDWG as a percentage of body weight (%IDWG) was associated with a younger age, greater height and weight, absence of diuresis, and lower postdialysis plasma sodium levels. The model with these five parameters explained 37% of the variance of %IDWG. Predialysis, intradialysis, and postdialysis diastolic blood pressure was significantly higher in the highest tertile of IDWG. Conclusion: The most important associations of %IDWG are age, height, weight, diuresis, and postdialysis sodium. Patients with the highest IDWG have significantly higher diastolic blood pressures.