Abstract Context The pathophysiology of cystinosis-associated metabolic bone disease is complex. Objective We hypothesized a disturbed interaction between osteoblasts and osteoclasts. Methods This ...binational cross-sectional multicenter study included 103 patients with cystinosis (61% children) with chronic kidney disease (CKD) stages 1 to 5D/T at hospital clinics. Ten key bone markers were evaluated. Results Skeletal complications occurred in two-thirds of the patients, with adults having a 5-fold increased risk compared with children. Patients with CKD stages 1 to 3 showed reduced z-scores for serum phosphate and calcium and suppressed fibroblast growth factor 23 (FGF23) and parathyroid hormone levels, in conjunction with elevated bone-specific alkaline phosphatase levels. Serum phosphate was associated with estimated glomerular filtration rate, combined phosphate and active vitamin D treatment, and native vitamin D supplementation, while serum calcium was associated with age and dosage of active vitamin D. Sclerostin was generally elevated in children, and associated with age, FGF23 levels, and treatment with active vitamin D and growth hormone. The osteoclast marker tartrate-resistant acid phosphatase 5b was increased, and associated with age and treatment with active vitamin D. The ratio of soluble ligand of receptor activator of nuclear factor-κB (sRANKL) and osteoprotegerin (OPG), a surrogate for the regulation of osteoclastogenesis by osteoblasts, was decreased and associated with phosphate and 1,25(OH)2D3 levels. These changes were only partly corrected after transplantation. Conclusion Bone health in cystinosis deteriorates with age, which is associated with increased osteoclast activity despite counter-regulation of osteoblasts via OPG/RANKL, which in conjunction with elevated sclerostin levels and persistent rickets/osteomalacia, may promote progressive bone loss.
Introduction: Mycophenolate mofetil (MMF) is an ester prodrug of the immunosuppressant mycophenolic acid (MPA) and is recommended and widely used for maintenance immunosuppressive therapy in solid ...organ and stem-cell transplantation as well as in immunological kidney diseases. MPA is a potent, reversible, noncompetitive inhibitor of the inosine monophosphate dehydrogenase (IMPDH), a crucial enzyme in the de novo purine synthesis in T- and B-lymphocytes, thereby inhibiting cell-mediated immunity and antibody formation. The use of therapeutic drug monitoring (TDM) of MMF is still controversial as outcome data of clinical trials are equivocal.
Areas covered: This review covers in great depth the existing literature on TDM of MMF in the field of pediatric (kidney) transplantation. In addition, the relevance of TDM in immunological kidney diseases, in particular childhood nephrotic syndrome is highlighted.
Expert opinion: TDM of MMF has the potential to optimize therapy in pediatric transplantation as well as in nephrotic syndrome. Limited sampling strategies to estimate MPA exposure increase its feasibility. Future perspectives rather encompass approaches reflecting total immunosuppressive load than single drug TDM.
Chronic kidney disease (CKD) directly affects oral health. Yet data about halitosis in young CKD patients and the impact of dental prophylaxis is limited. Therefore, as part of this randomized ...clinical trial, halitosis in young CKD patients undergoing intensive or standard oral preventive procedures was to be explored.
Three volatile sulfur compounds (hydrogen sulfide, methyl mercaptan and dimethyl sulfide) were measured in 30 young patients with CKD (mean age 14.2 years; 16 males, 14 females). Breath samples were taken after 3 and 6 months and analyzed with selective gas chromatography (OralChroma). Tongue coating (Winkel Index) and clinical indices to determine local inflammation or oral hygiene (Papillary Bleeding Index and Quigley-Hein Index) were assessed. Within an extended anamnesis, patients and their mothers and nurses were questioned about the perceived halitosis. Corresponding quotes were noted verbatim. Patients were randomized to either intensive need-related oral health care measures (oral preventative program, OPP) or a one-stage standard prevention (treatment as usual, TAU).
While there were no differences in volatile sulfur compound levels between TAU and OPP at the three time points of measurements (p > 0.05), there was a tendency towards a reduction in dimethyl sulfide and hydrogen sulfide of affected patients within the OPP group over time. Looking at potential differences between both groups with regard to tongue coating, significant differences were observed between baseline and 3 months after study start in the OPP group, and between baseline and 6 months after study start in the TAU group (p < 0.05). The burden of halitosis was frequently reported by patients' mothers and nurses.
Young CKD patients regularly suffered from halitosis and dimethyl sulfide was its main source. Preventive measures mainly resulted in a reduction of tongue coating.
The German Clinical Trial Register (# DRKS00010580).
Recurrence of primary disease is one of the major risks for allograft loss after pediatric RTx. The risk of recurrence of FSGS/SRNS after pediatric RTx in particular can be up to 86% in idiopathic ...cases. There is a need for consensus recommendations on its prevention and treatment. The CERTAIN study group has therefore performed a thorough literature search based on the PICO model of clinical questions to formulate educated statements to guide the clinician in the process of decision‐making. A set of educated statements on prevention and treatment of FSGS/SRNS after pediatric RTx has been generated after careful evaluation of available evidence and thorough panel discussion. We do not recommend routine nephrectomy prior to transplantation; neither do we recommend abstaining from living donation. Special attendance needs to be given to those patients who had already experienced graft loss due to FSGS/SRNS recurrence. Early PE or IA with or without high‐dose CsA and/or rituximab seems to be most promising to induce remission. The educated statements presented here acknowledge that FSGS/SRNS recurrence after pediatric RTx remains a major concern and is associated with shorter graft survival or even graft loss. The value of any recommendation needs to take into account that evidence is based on cohorts that differ in ethnicity, pre‐transplant history, immunosuppressive regimen, definition of recurrence (eg, clinical and/or histological diagnosis) and treatment modalities of recurrence.
ABSTRACT Background Clinical trials have demonstrated positive cardiovascular and kidney outcomes of sodium–glucose co-transporter 2 (SGLT2) inhibitors in adult patients with diabetic and other ...chronic kidney diseases (CKDs). Whether benefits extend to children, teenagers and young adults with early-stage CKD is unknown. For this reason, the DOUBLE PRO-TECT Alport trial (NCT05944016) will study the progression of albuminuria in young patients with Alport syndrome (AS), the most common hereditary CKD, to assess the safety and efficacy of the SGLT2 inhibitor dapagliflozin. Patients living with AS and chronically elevated albuminuria have a high risk of kidney failure before the age of 50 years. Methods DOUBLE PRO-TECT Alport is a multicentre, randomized, double-blind, placebo-controlled trial. Participants (ages 10–39 years) must have a diagnosis of AS by genetic testing or kidney biopsy, be on a stable (>3 months) maximum tolerated dose of a renin–angiotensin system inhibitor and have a urinary albumin:creatinine ratio (UACR) of >300 mg/g (paediatric) or >500 mg/g (adult). Eligible participants will be randomly assigned at a 2:1 ratio to 48 weeks of treatment with dapaglifozin 10 mg/day or matched placebo. Most participants are expected to be children with a normal estimated glomerular filtration rate (eGFR). In addition to safety, the primary (change in UACR from baseline to week 48) and key secondary (eGFR change from baseline to week 52) efficacy outcomes will be analysed with a mixed model repeated measures approach. Efficacy analyses will be performed primarily in the full analysis set according to the intention-to-treat principle. A sensitivity analysis will be performed using reference-based multiple imputation. Conclusion DOUBLE PRO-TECT Alport will assess whether SGLT2 inhibitors can safely reduce the UACR change from baseline as a marker for progression of CKD in young patients living with AS.
Mycophenolate mofetil (MMF) plays an increasingly important role in the treatment of children with nephrotic syndrome, especially in steroid sparing protocols. Recent publications show the ...relationship of exposure to its active moiety mycophenolic acid (MPA) and clinical efficacy. Performance of full-time pharmacokinetic (PK) profiles, however, is inconvenient and laborious. Established limited sampling strategies (LSS) to estimate the area under the concentration (AUC) versus time curve of MPA (MPA-AUC) in pediatric renal transplant recipients cannot be easily transferred to children suffering from nephrotic syndrome, mainly because of the lack of concomitant immunosuppressive therapy. We therefore aimed for the generation and validation of a LSS to estimate MPA exposure to facilitate therapeutic drug monitoring in children with nephrotic syndrome.
We performed 27 complete PK profiles in 23 children in remission mean age (±SD):12.3 ± 4.26 years to generate and validate an LSS. Sampling time points were before administration (C0) and 0.5, 1, 1.5, 2, 4, 6, 8, and 12 hours after the administration of MMF. MPA was measured by enzyme multiplied immunoassay technique. There was no concomitant treatment with calcineurin inhibitors.
Mean daily dose of MMF was 927 ± 209 mg/m of body surface area resulting in a mean MPA-AUC0-12 value of 59.2 ± 29.3 mg × h/L and a predose level of 3.03 ± 2.24 mg/L. Between-patient variability of dose-normalized MPA-AUC0-12 was high (coefficient of variation: 45.5%). Correlation of predose levels with the corresponding MPA-AUC0-12 was moderate (r = 0.59) in a subgroup of 18 patients (20 PK profiles, generation group). An algorithm based on 3 PK sampling time points during the first 2 hours after MMF dosing (estimated AUC0-12 = 8.7 + 4.63 × C0 + 1.90 × C1 + 1.52 × C2) was able to predict MPA-AUC with a low percentage prediction error (3.88%) and a good correlation of determination (r = 0.90). Validation of this algorithm in a randomized separate group of 6 patients (7 PK profiles, validation group) resulted in comparably good correlation (r = 0.95) and low percentage prediction error (5.57%).
An abbreviated profile within the first 2 hours after MMF dosing gives a good estimate of MPA exposure in children with nephrotic syndrome and hence has the potential to optimize MMF therapy.
Abstract
Context
Children with nephropathic cystinosis (NC) show persistent hypophosphatemia, due to Fanconi syndrome, as well as mineral and bone disorders related to chronic kidney disease (CKD); ...however, systematic analyses are lacking.
Objective
To compare biochemical parameters of bone and mineral metabolism between children with NC and controls across all stages of CKD.
Design
Cross-sectional multicenter study.
Setting
Hospital clinics.
Patients
Forty-nine children with NC, 80 CKD controls of the same age and CKD stage.
Main outcome measures
Fibroblast growth factor 23 (FGF23), soluble Klotho, bone alkaline phosphatase (BAP), tartrate-resistant acid phosphatase 5b (TRAP5b), sclerostin, osteoprotegerin (OPG), biochemical parameters related to mineral metabolism, and skeletal comorbidity.
Results
Despite Fanconi syndrome medication, NC patients showed an 11-fold increased risk of short stature, bone deformities, and/or requirement for skeletal surgery compared with CKD controls. This was associated with a higher frequency of risk factors such as hypophosphatemia, hypocalcemia, low parathyroid hormone (PTH), metabolic acidosis, and a specific CKD stage-dependent pattern of bone marker alterations. Pretransplant NC patients in mild to moderate CKD showed a delayed increase or lacked an increase in FGF23 and sclerostin, and increased BAP, TRAP5b, and OPG concentrations compared with CKD controls. Post-transplant, BAP and OPG returned to normal, TRAP5b further increased, whereas FGF23 and PTH were less elevated compared with CKD controls and associated with higher serum phosphate.
Conclusions
Patients with NC show more severe skeletal comorbidity associated with distinct CKD stage-dependent alterations of bone metabolism than CKD controls, suggesting impaired mineralization and increased bone resorption, which is only partially normalized after renal transplantation.
The outcome of extremely low-birth-weight (ELBW) and very low-birth-weight (VLBW) infants has substantially improved in recent years. As acute kidney injury is frequent in these infants due to ...various risk factors, there is an increasing demand for renal replacement therapy in these patients. Data on that topic, however, are scarce. We review the available literature on that topic and report our experience on temporary dialysis in three extremely immature infants (two ELBW and one VLBW) with acute kidney failure. Peritoneal dialysis (PD) was performed for 19, 23, and 44 days until recovery of native renal function. At recent follow-up of 18 and 24 months, two patients are in good clinical condition with chronic kidney disease stages 1 and 4, respectively. One patient deceased at the age of 12 months due to secondary liver failure. The dialysis regimen applied in our study differed significantly from older infants with extremely short dwell times and accordingly high numbers of daily cycles. The use of rigid acute PD catheters was associated with less catheter-related complications (leakage, dislocation, and obstruction) as compared to ascites drainage catheters. In summary, PD was technically feasible and effective also in extremely immature infants, but frequent adjustments of dialysis regimens and high numbers of daily cycles posed immense efforts on both, parents and medical staff.
Mycophenolic acid (MPA), a powerful inhibitor of lymphocyte proliferation, is widely used in transplantation medicine and as a glucocorticoid-sparing agent in rheumatic and inflammatory diseases. As ...inosine-5'-monophosphate dehydrogenase (IMPDH), the target enzyme of MPA, shows high interindividual variability in its basal activity, the assessment of IMPDH activity in addition to pharmacokinetic monitoring has emerged as a strategy to individualize MPA pharmacotherapy.
A liquid chromatography-tandem mass spectrometry method was developed to measure IMPDH activity in peripheral blood mononuclear cells from lithium-heparinized blood. Stable isotope-labeled analogs of analytes were used as internal standards for the quantitative analyses of xanthosine-5'-monophosphate (XMP) and adenosine-5'-monophosphate (AMP). IMPDH activity was expressed as enzymatic production of XMP per time normalized to the AMP concentration. Validation and evaluation of the new method were performed by using blood samples from healthy volunteers (n = 10).
Linearity was demonstrated over the concentration ranges of 0.25-80 μM for XMP and 4-80 µM for AMP (R > 0.99). Between-day and within-day assay precisions and accuracies were within the acceptance criterion of ±15%. Matrix effects were fully compensated by the coelution of internal standards. Specific and linear XMP production (R > 0.99) and the inhibition of IMPDH activity by MPA at clinically relevant doses were demonstrated.
In this study, a liquid chromatography-tandem mass spectrometry method to measure IMPDH activity was established and fully evaluated for matrix and ion suppression effects. The method enabled precise quantification of IMPDH activity for the improvement of pharmacokinetic/pharmacodynamic therapeutic drug monitoring approaches to optimize immunosuppressive treatment with MPA.
