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Objectives: To examine the relationship between kidney hyperfiltration during adolescence and subsequent changes in estimated glomerular filtration rate (eGFR) and urinary albumin creatinine ratio (UACR) in a young cohort of participants with type 1 diabetes. Additionally, to explore urinary mitochondrial DNA:nuclear DNA ratio (mtDNA:nDNA) as a marker of metabolic stress and its association with early changes in kidney function., Methods: Eighty adolescents were studied at baseline [mean (SD) age 14.2 (1.5) years; mean diabetes duration 6.7 (3.0) years] and followed up 9.2 (1.3) years later. Blood pressure, HbA1c, lipids, eGFR, UACR and heart rate variability were assessed at each visit. Urinary mtDNA:nDNA was measured by quantitative PCR (qPCR)., Results: Overall, 4.2% of participants had diabetic kidney disease (DKD) at follow-up. Hyperfiltration at baseline (>135 mL/min/1.73m2) was seen in 31% of adolescents and was associated with a decline in eGFR at follow-up when adjusted for sex, diabetes duration and HbA1c [hyperfiltration -1.46 (3.07) mL/min/1.73 m2/year vs non-hyperfiltration -0.51 (2.48) mL/min/1.73m2/year, P=0.02]. Participants with hyperfiltration also had higher odds of undergoing rapid eGFR decline (>3 mL/min/1.73m2/year) compared to those without hyperfiltration [OR 14.11, 95% CI (2.30-86.60), P=0.004]. Baseline urinary mtDNA:nDNA was significantly associated with both greater annual rate of eGFR decline and rapid eGFR decline in univariable but not multivariable modelling., Conclusion: Hyperfiltration during adolescence is significantly associated with greater reduction in eGFR and higher risk of rapid eGFR decline after ∼9 years, following transition into young adulthood in type 1 diabetes. Urinary mtDNA:nDNA measured during adolescence may be a novel predictor of early changes in kidney function., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com. See the journal About page for additional terms.)

In clinical practice, the glomerular filtration rate (GFR), a measurement of kidney functioning, is normally calculated using equations, such as the European Kidney Function Consortium (EKFC) equation. Despite being the most general equation, EKFC, just like previously proposed approaches, can still struggle to achieve satisfactory performance, limiting its clinical applicability. As a possible solution, recently machine learning (ML) has been investigated to improve GFR prediction, nonetheless the literature still lacks a general and multi-center study. Using a dataset with 19,629 patients from 13 cohorts, we investigate if ML can improve GFR prediction in comparison to EKFC. More specifically, we compare diverse ML methods, which were allowed to use age, sex, serum creatinine, cystatin C, height, weight and BMI as features, in internal and external cohorts against EKFC. The results show that the most performing ML method, random forest (RF), and EKFC are very competitive where RF and EKFC achieved respectively P10 and P30 values of 0.45 (95% CI 0.44;0.46) and 0.89 (95% CI 0.88;0.90), whereas EKFC yielded 0.44 (95% CI 0.43; 0.44) and 0.89 (95% CI 0.88; 0.90), considering the entire cohort. Small differences were, however, observed in patients younger than 12 years where RF slightly outperformed EKFC., (© 2024. The Author(s).)

International consensus supports the development of standardized protocols for measured glomerular filtration rate (mGFR) to facilitate the integration of mGFR testing in both clinical and research settings. To this end, the European Kidney Function Consortium convened an international group of experts with relevant experience in mGFR. The working group performed an extensive literature search to inform the development of recommendations for mGFR determination using 1-compartment plasma clearance models and iohexol as the exogenous filtration marker. Iohexol was selected as it is non-radio labeled, inexpensive, and safe, can be assayed at a central laboratory, and the other commonly used non-radio-labeled tracers have been (inulin) or are soon to be (iothalamate) discontinued. A plasma clearance model was selected over urine clearance as it requires no urine collection. A 1 compartment was preferred to 2 compartments as it requires fewer samples. The recommendations are based on published evidence complemented by expert opinion. The consensus paper covers practical advice for patients and health professionals, preparation, administration, and safety aspects of iohexol, laboratory analysis, blood sample collection and sampling times using both multiple and single-sample protocols, description of the mGFR mathematical calculations, as well as implementation strategies. Supplementary materials include patient and provider information sheets, standard operating procedures, a study protocol template, and support for mGFR calculation., (Copyright © 2024 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Background: Estimation of glomerular filtration rate using equations based on creatinine is widely used to manage chronic kidney disease. In the UK, the Chronic Kidney Disease Epidemiology Collaboration creatinine equation is recommended. Other published equations using cystatin C, an alternative marker of kidney function, have not gained widespread clinical acceptance. Given higher cost of cystatin C, its clinical utility should be validated before widespread introduction into the NHS., Objectives: Primary objectives were to: (1) compare accuracy of glomerular filtration rate equations at baseline and longitudinally in people with stage 3 chronic kidney disease, and test whether accuracy is affected by ethnicity, diabetes, albuminuria and other characteristics; (2) establish the reference change value for significant glomerular filtration rate changes; (3) model disease progression; and (4) explore comparative cost-effectiveness of kidney disease monitoring strategies., Design: A longitudinal, prospective study was designed to: (1) assess accuracy of glomerular filtration rate equations at baseline ( n  = 1167) and their ability to detect change over 3 years ( n  = 875); (2) model disease progression predictors in 278 individuals who received additional measurements; (3) quantify glomerular filtration rate variability components ( n  = 20); and (4) develop a measurement model analysis to compare different monitoring strategy costs ( n  = 875)., Setting: Primary, secondary and tertiary care., Participants: Adults (≥ 18 years) with stage 3 chronic kidney disease., Interventions: Estimated glomerular filtration rate using the Chronic Kidney Disease Epidemiology Collaboration and Modification of Diet in Renal Disease equations., Main Outcome Measures: Measured glomerular filtration rate was the reference against which estimating equations were compared with accuracy being expressed as P30 (percentage of values within 30% of reference) and progression (variously defined) studied as sensitivity/specificity. A regression model of disease progression was developed and differences for risk factors estimated. Biological variation components were measured and the reference change value calculated. Comparative costs of monitoring with different estimating equations modelled over 10 years were calculated., Results: Accuracy (P30) of all equations was ≥ 89.5%: the combined creatinine-cystatin equation (94.9%) was superior ( p  < 0.001) to other equations. Within each equation, no differences in P30 were seen across categories of age, gender, diabetes, albuminuria, body mass index, kidney function level and ethnicity. All equations showed poor (< 63%) sensitivity for detecting patients showing kidney function decline crossing clinically significant thresholds (e.g. a 25% decline in function). Consequently, the additional cost of monitoring kidney function annually using a cystatin C-based equation could not be justified (incremental cost per patient over 10 years = £43.32). Modelling data showed association between higher albuminuria and faster decline in measured and creatinine-estimated glomerular filtration rate. Reference change values for measured glomerular filtration rate (%, positive/negative) were 21.5/-17.7, with lower reference change values for estimated glomerular filtration rate., Limitations: Recruitment of people from South Asian and African-Caribbean backgrounds was below the study target., Future Work: Prospective studies of the value of cystatin C as a risk marker in chronic kidney disease should be undertaken., Conclusions: Inclusion of cystatin C in glomerular filtration rate-estimating equations marginally improved accuracy but not detection of disease progression. Our data do not support cystatin C use for monitoring of glomerular filtration rate in stage 3 chronic kidney disease., Trial Registration: This trial is registered as ISRCTN42955626., Funding: This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 11/103/01) and is published in full in Health Technology Assessment ; Vol. 28, No. 35. See the NIHR Funding and Awards website for further award information.

Glycogen storage disease type Ib (GSD Ib, biallelic variants in SLC37A4) is a rare disorder of glycogen metabolism complicated by neutropenia/neutrophil dysfunction. Since 2019, the SGLT2-inhibitor empagliflozin has provided a mechanism-based treatment option for the symptoms caused by neutropenia/neutrophil dysfunction (e.g. mucosal lesions, inflammatory bowel disease). Because of the rarity of GSD Ib, the published evidence on safety and efficacy of empagliflozin is still limited and does not allow to develop evidence-based guidelines. Here, an international group of experts provides 14 best practice consensus treatment recommendations based on expert practice and review of the published evidence. We recommend to start empagliflozin in all GSD Ib individuals with clinical or laboratory signs related to neutropenia/neutrophil dysfunction with a dose of 0.3-0.4 mg/kg/d given as a single dose in the morning. Treatment can be started in an outpatient setting. The dose should be adapted to the weight and in case of inadequate clinical treatment response or side effects. We strongly recommend to pause empagliflozin immediately in case of threatening dehydration and before planned longer surgeries. Discontinuation of G-CSF therapy should be attempted in all individuals. If available, 1,5-AG should be monitored. Individuals who have previously not tolerated starches should be encouraged to make a new attempt to introduce starch in their diet after initiation of empagliflozin treatment. We advise to monitor certain safety and efficacy parameters and recommend continuous, alternatively frequent glucose measurements during the introduction of empagliflozin. We provide specific recommendations for special circumstances like pregnancy and liver transplantation., Competing Interests: Declaration of competing interest All authors with exception of ELC, JlF, PH and SKU received accommodation support by Sophie's Hope Foundation. All authors report no conflict of interest related to this study. TGJD declares that he has confidentiality agreements with third parties. In the past 36 months, there have been consultation agreements (with Danone, Ultragenyx Pharmaceutical Inc, ModernaTX Inc., and Beam Therapeutics), contracts for financial research support for investigator-initiated research (NCT04311307) and sponsor-initiated research (NCT03517085, NCT03970278, NCT05139316, and NCT05196165), honoraria for lectures or presentations (by MEDTalks, Prelum, and Danone), and participations in a Data Safety Monitoring Board (NCT05095727) and Advisory Boards (Ultragenyx Pharmaceutical Inc, ModernaTX Inc., and Beam Therapeutics). For all private-public relationships, all contracts are via UMCG Contract Research Desk and all payments are to UMCG. ND declares that he is a director and minority shareholder in SpOtOn Clinical Diagnostics Ltd. KMS declares that in the last 36 months there were consultancy agreements with BioMarin, Chiesi, Takeda, Sanofi, Amicus and Immusoft Corporation. SCG declares that over the last 3 years in the area of inherited metabolic diseases she has received accommodation support from Nutricia Metabolics, honoraria for lectures from Vitaflo and Ultragenyx, and that she is an advisory board member of Ultragenyx. JL and BS declare no conflict of interest. Funding to Sophie's Hope Foundation and curegsd1b.org is by individual donors, rather than pharmaceutical or medical food industry. ELC declares no conflict of interest. C.D. Nina la Guerrera (www.ninalaguerrera.org) is a small size non-for-profit platform, whose main sources of funding are by individual donors from sectors that have no interest in biomedical research. HM declares that over the last 3 years in the area of inherited metabolic diseases she has received accommodation support from Vitaflo. honoraria for lectures from Vitaflo and Nutricia and served as a paid consultant for Ultragenyx. SBW declares that over the last 3 years in the area of inherited metabolic diseases she has received accommodation support from Nutricia Metabolics., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)