Rule, Andrew D

Background: Hypertensive disorders of pregnancy (HDP), gestational diabetes mellitus (GDM), and preterm delivery are associated with higher long-term cardiovascular, metabolic, and kidney disease risk. Their implications for living kidney donation remain uncertain. Methods: We conducted a retrospective cohort study of 498 female living kidney donors (2000–2017) from the Mayo Clinic Living Donor Program with documented pregnancy histories, pre-donation CT angiography, implantation kidney biopsy, and measured GFR. Donors with prior HDP (n=45), GDM (n=18), or preterm delivery (n=65) were compared with donors without adverse pregnancy outcomes (APO; n=385). Kidney morphometry, histology, and function were analyzed with adjustment for age at donation and first pregnancy, parity, and hypertension. Post-donation kidney outcomes were assessed using surveys and medical record review. Results: Donors with prior HDP and GDM had higher BMI at donation (+7.9% and +8.9%; p=0.006 and 0.04), whereas donors with preterm delivery had lower BMI (−4.8%; p=0.03) compared with donors with no APO. After adjustment, donors with HDP showed no differences in kidney volumes, biopsy features, or kidney function at donation or during follow-up. Donors with GDM had larger total and cortical kidney volumes (9.5–10%), less arterial luminal stenosis, and higher 5-year post-donation eGFR (+15%; p=0.03). Donors with preterm delivery had a lower risk of eGFR <45 mL/min/1.73 m 2 (HR 0.28; p=0.03). Conclusions: Prior adverse pregnancy outcomes were not associated with adverse kidney structure at donation or accelerated kidney function decline post-donation. These findings support that APO history alone should not preclude living kidney donation when other eligibility criteria are met.

The extent to which eGFR varies across populations, in the absence of risk factors and comorbidities associated with kidney disease, remains uncertain. We aimed to develop eGFR reference values in healthy American adults and to compare them with previously described European eGFR reference values. This cross-sectional study compared newly described age-specific and sex-specific creatinine-based eGFR reference values from over 9000 healthy Americans from National Health and Nutrition Examination Survey with previously described eGFR reference values from over 1.5 million healthy individuals in the European CKD Burden Consortium. Health status was based on 14 criteria related to comorbidities, lifestyle factors, and medication use. eGFR was calculated using the European Kidney Function Consortium equation and modeled over the age span and by sex using a generalized additive model. The median eGFR in both 20-year-old American and European men was 98 ml/min per 1.73 m 2 . In both 20-year-old American and European women, the median eGFR was 101 ml/min per 1.73 m 2 . eGFR started to decrease at age 40 years, a result of the structure of the European Kidney Function Consortium equation. By age 79 years, the median eGFR in American and European men was 68 and 67 ml/min per 1.73 m 2 , respectively. The median eGFR in 79-year-old American and European women was 63 and 64 ml/min per 1.73 m 2 , respectively. When removing the effect of comorbidities, lifestyle factors and medication use associated with kidney function, achieved by restricting the analyses to individuals who did not have a presence or history of certain criteria, the distribution of eGFR was similar between healthy Americans and Europeans. This supports the notion that eGFR reference values may be generalizable to populations they were not derived from.

Key Points Increased protein expression of tissue inhibitor of metalloproteinase-3, glypican 6, synuclein γ , apolipoprotein A-4, and Ecto-5′-nucleotidase was observed in old adults compared with young adults. In old adults, overexpressed proteins were enriched in mitochondrial processes while under expressed proteins enriched in RNA metabolism. Validated differentially expressed proteins were not significantly correlated with kidney pathology after adjusting for age. Background Kidney aging is characterized by a loss of glomeruli, predominantly in the superficial cortex, with a resultant decline in GFR and an increased risk of various kidney-related diseases. The early molecular alterations in glomeruli associated with the aging process are not well studied. Methods We combined laser capture microdissection and mass spectrometry–based unbiased proteomic analysis of nonsclerosed, nonischemic glomeruli in the superficial cortex from young and old adults who underwent a radical nephrectomy for a tumor to understand the age-related molecular changes in glomeruli. Twenty-four young and 30 old adults were used for the discovery dataset, and the significant differentially expressed proteins were further validated using an independent set comprising six young and eight old adults. Results Kidneys from old adults had lower eGFR, less kidney parenchyma on computed tomography imaging, and more glomerulosclerosis and arteriosclerosis on histology. Quantitative proteomic analysis of nonsclerosed, nonischemic glomeruli identified increased expression of tissue inhibitor of metalloproteinase-3, glypican 6, synuclein γ , apolipoprotein A-4, and Ecto-5′-nucleotidase in old adults that were further validated in an independent set. Pathway analysis indicated that proteins with increased expression in old adults were enriched in mitochondrial translational processes, aerobic respiration, and TCA cycle, whereas proteins with decreased expression in old adults were enriched in mRNA splicing, mRNA processing, and nonsense mediated decay. Furthermore, validated differentially expressed proteins did not show any significant correlation with the kidney pathology independent of age group. Conclusions Overall, this study identified proteins that are specifically associated with the aging process in otherwise normal-appearing glomeruli.

Key Points Among US preemptively waitlisted patients with CKD, deceased donor transplants increased for Black and Hispanic patients, comparable with White patients. Dialysis initiation was higher for waitlisted Asian, Black, and Hispanic patients compared with White patients, mirroring lower living donor transplants. Organ Procurement and Transplantation Network wait time credit and Increasing Organ Transplant Access metric could expand preemptive transplantation. Background Preemptive kidney transplantation (before dialysis initiation) is the optimal therapy for most transplant-eligible advanced patients with CKD. Although prior research has documented racial and ethnic disparities in preemptive referrals, less is known about distinct outcomes after preemptive waitlisting. This study examines the association between race and ethnicity and outcomes for preemptively waitlisted patients. Methods We conducted a secondary analysis of a prospectively maintained US cohort using data from the Scientific Registry of Transplant Recipients. The study population included 98,863 adult first-time kidney transplant candidates who were preemptively waitlisted from January 1, 2009, to December 31, 2020, and followed through December 31, 2024. The exposure of interest was race and ethnicity. The primary outcome was 3-year preemptive deceased donor kidney transplantation, living donor kidney transplantation, or dialysis initiation. We used competing risk models to estimate adjusted subdistribution hazard ratios (aSHRs). Data were stratified into 3-year intervals (2009–2011, 2012–2014, 2015–2017, and 2018–2020). Results Black and Hispanic patients received preemptive deceased donor kidney transplants as often as White patients (era 2018–2020, aSHRs [95% confidence interval (CI)]: 0.99 [95% CI, 0.92 to 1.07] and 1.02 [95% CI, 0.93 to 1.12], respectively), while Asian patients had lower rates (0.78 [95% CI, 0.69 to 0.88]). However, Asian, Black, and Hispanic patients were more likely to initiate dialysis (aSHRs: 1.50 [95% CI, 1.39 to 1.61]; 1.41 [95% CI, 1.34 to 1.49]; and 1.21 [95% CI, 1.14 to 1.29], respectively) and were less likely to receive preemptive living donor kidney transplants than White patients (era 2018–2020, aSHRs: 0.49 [95% CI, 0.44 to 0.54]; 0.31 [95% CI, 0.29 to 0.34]; and 0.61 [95% CI, 0.56 to 0.66], respectively). Conclusions Among waitlisted patients with CKD in the United States between 2009 and 2020, rates of preemptive deceased donor kidney transplantation improved for Black and Hispanic patients and became comparable with White patients. However, Asian, Black, and Hispanic patients experienced higher rates of dialysis initiation and lower rates of preemptive living donor kidney transplantation.

BACKGROUND: The performance of estimated glomerular filtration rate (eGFR) among patients with heart failure (HF) may be worse than in the general population due to a higher prevalence of confounding factors affecting creatinine and cystatin C. Studies in this area are scarce and not stratified by type of HF. We evaluated the performance of current creatinine and cystatin C equations (eGFRcr, eGFRcys, and eGFRcrcys) compared with measured GFR (mGFR) among patients with HF stratified by ejection fraction. METHODS: We pulled data on Mayo Clinic patients with an mGFR performed for clinical indications from 2011 to 2023, with serum creatinine and cystatin C measured within 7 days and an echocardiogram performed up to 1 year before the mGFR date. HF was identified by the presence of International Classification of Diseases codes within 1 year before the mGFR and subgrouped into ejection fraction (EF) ≥50% (HFEF≥50%, n=182) or <50% (HFEF<50%, n=115) and compared with no-HF controls (n=1871). CKD-EPI (and EKFC) eGFRcr, eGFRcys, and eGFRcrcys equations were calculated and compared for bias (mGFR minus eGFR) and accuracy (1-P30, proportion of people with ≥30% difference between eGFR and mGFR). CIs were generated by bootstrapping. RESULTS: The HF groups were characterized by older age, higher proportion of males, more diabetes, higher creatinine, and higher cystatin C than controls. In terms of bias, eGFRcr overestimated mGFR to a greater extent in both HF groups compared with controls, whereas eGFRcys and eGFRcrcys showed similar bias in both HF groups and controls. In the HF groups, cystatin C-based equations were more accurate than eGFRcr, particularly within HFEF<50% (1-P30 of 28% and 34% for CKD-EPI eGFRcys and eGFRcrcys, respectively, versus 60% for eGFRcr), whereas eGFRcrcys was more accurate in controls. The CKD-EPI and EKFC equations were overall convergent, showing similar results. CONCLUSIONS: Among patients with HF, eGFRcr demonstrates inferior performance (more bias and less accuracy) compared with cystatin C-based eGFRs, with this effect being more pronounced in those with HFEF<50%.

Key Points Automated cyst segmentation in autosomal dominant polycystic kidney disease could transform care by enabling precise monitoring of cyst progression with minimal manual effort. This technology can facilitate more consistent assessments of cyst burden across patients. Translating these segmentation models from magnetic resonance imaging to computed tomography is crucial for providing comprehensive, modality-independent evaluations. Background Total kidney and liver volumes are key image-based biomarkers to predict the severity of kidney and liver phenotype in autosomal dominant polycystic kidney disease (ADPKD). However, magnetic resonance (MR) imaging-based advanced biomarkers like total cyst number and cyst parenchyma surface area have been shown to more accurately assess cyst burden and improve the prediction of disease progression. The main aim of this study was to extend the calculation of advanced biomarkers to other imaging modalities; thus, we propose a fully automated model to segment kidney and liver cysts in computed tomography (CT) images. Methods Abdominal CTs of patients with ADPKD were gathered retrospectively between 2001 and 2018. A three-dimensional deep learning method using the nnU-Net architecture was trained to learn cyst edges-cores and the noncystic kidney/liver parenchyma. Separate segmentation models were trained for kidney cysts in contrast-enhanced CTs and liver cysts in noncontrast CTs using an active learning approach. Two experienced research fellows manually generated the reference standard segmentation, which were reviewed by an expert radiologist for accuracy. Results Two-hundred CT scans from 148 patients (mean age, 51.2±14.1 years; 48% male) were used for model training (80%) and testing (20%). In the test set, both models showed good agreement with the reference standard segmentations, similar to the agreement between two independent human readers (model versus reader: TCN kidney/liver r =0.96/0.97 and CPSA kidney r =0.98, inter-reader: TCN kidney/liver r =0.96/0.98 and CPSA kidney r =0.99). Conclusions Our study demonstrates that automated models can segment kidney and liver cysts accurately in CT scans of patients with ADPKD.

Key Points Circulating proteins independently associated with kidney stone diagnosis are related to kidney stone matrix. Lower circulating uromodulin and higher scavenger receptor cysteine-rich domain-containing group B protein levels were associated with higher kidney stone risk, whereas kidney stone presence elevates plasma matrix metalloproteinase 7 level. The protective effect of uromodulin against kidney stones was independent of kidney function. Background Kidney stones are increasingly recognized as a systemic disorder with a high global prevalence. However, large proteomics studies are lacking. Methods An individual-level proteomics study with rigorous adjustments was performed on 35,331 UK Biobank participants to uncover the independent associations between 2922 circulating proteins and prevalent kidney stone disease. Mendelian randomization analysis was used to assess causal relationships. Findings were validated using genomic data from the Mayo Clinic Biobank ( N =43,744), concentration-response analysis, transcriptomics analyses, and additional genome-wide association studies. Results Nine plasma proteins were independently associated with a kidney stone diagnosis, including reduced uromodulin (UMOD; β , −0.10; 95% confidence interval [CI], −0.15 to −0.05) and elevated scavenger receptor cysteine-rich domain-containing group B protein (SSC4D; β , 0.28; 95% CI, 0.17 to 0.38) and were enriched in extracellular matrix pathways. Mendelian randomization analysis revealed that the presence of kidney stone contributed to elevated levels of matrix metalloproteinase 7. Conversely, lower plasma UMOD (odds ratio [OR], 0.93; 95% CI, 0.90 to 0.97) and higher plasma SSC4D (OR, 1.10; 95% CI, 1.02 to 1.18) were associated with kidney stone risk. These associations were consistently replicated in the Mayo Clinic Biobank dataset (UMOD; OR, 0.92; 95% CI, 0.86 to 0.98; SSC4D; OR, 1.13; 95% CI, 1.01 to 1.27) and further validated by a concentration-response analysis. Single-nucleus RNA sequencing and quantitative trait loci analyses confirmed consistent associations between thick ascending limb UMOD expression and stone former status and with blood and urine UMOD concentrations. Genome-wide association study analysis, adjusted for eGFR, suggested that the protective role of UMOD against kidney stones was independent of kidney function. Conclusions This study highlights significant associations between concentrations of specific blood proteins and a history of kidney stones. Several implicated proteins are related to kidney stone matrix, with UMOD independently associated with lower risk and SSC4D with higher risk of kidney stones.

Key Points Studies on GFR assessment in people with cancer are needed. In this study, the creatinine–cystatin C equations performed better than other equations, and this was observed in solid and hematological cancers. Our findings give support to the preferential use of creatinine and cystatin C–based equations in people with cancer. Background GFR assessment is important in clinical practice with implications for diagnosis, prognostication, and drug dosing. People with cancer are at risk of imprecision in GFR estimation. This cross-sectional study evaluated the performance of various creatinine and cystatin C–based equations in comparison with measured GFR (mGFR) in people with cancer. Methods We retrieved data for all adult patients who had mGFR by urinary iothalamate clearance between 2011 and 2023 at Mayo Clinic and use of an electronic health record diagnosis code for cancer within 2 years before mGFR. The CKD Epidemiology Collaboration (CKD-EPI), European Kidney Function Consortium, and Cockcroft–Gault equations were computed, along with performance metrics (bias, precision, and root mean square error [RMSE]. Confidence intervals were generated by bootstrapping, and analysis were stratified by solid and hematological cancers. Results From all adults with cancer and mGFR, 1145 had both creatinine and cystatin C available within 7 days of mGFR. Among all equations, the creatinine–cystatin C CKD-EPI equation provided the best performance, with small bias (median, 3.0; 95% confidence interval, 2.3 to 3.8) and higher precision (RMSE, 14.5) compared with creatinine-only or cystatin C–only equations (RMSE varying from 16.6 to 20), and this was also true in solid and hematological cancers. The creatinine–cystatin European Kidney Function Consortium equation had a similar performance to CKD-EPI, Cockcroft–Gault showed worst precision (30% of people with errors above 30%), and cystatin C CKD-EPI equation was the most biased, prone to underestimation of mGFR. Conclusions In our cohort of patients with mGFR and cancer, the CKD-EPI creatinine–cystatin C equation performed best for GFR assessment, and this was true for both solid and hematological cancers. Our findings give support for the preferential use of creatinine and cystatin C–based equations instead of creatinine-only or cystatin C–only equations in people with cancer. Podcast This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2025_03_25_CJASNMar20.3.3252025.mp3

ABSTRACTCellular senescence is a biological mechanism of aging and age‐related diseases. The aim of this study was to examine whether senescence biomarkers are associated with frailty and physical function trajectories in patients undergoing kidney transplantation (KT). We also discussed the relationship between senescence biomarkers and KT function. In this multicenter study, we prospectively assessed plasma levels of senescence biomarkers, frailty as measured by the Physical Frailty Phenotype, and physical function as measured by the Short Physical Performance Battery prior to KT. Frailty, physical function, and KT function were also measured 1 year after KT. Variable associations were assessed using Cox and relaxed least absolute shrinkage and selection operation regression. The cohort consisted of 197 participants (mean age 53 ± 13 years, 61.4% male, and 80.2% White race). Higher pre‐KT levels of macrophage‐derived chemokine (MDC/CCL22) and growth differentiation factor‐15 (GDF‐15) were independently associated with less improvement in frailty and/or physical function during the first year after KT. Higher pre‐KT levels tumor necrosis factor receptor superfamily member 6 (FAS) and MMP‐9 levels were independently associated with lower KT function one year after KT. Pre‐KT cellular senescence may contribute to frailty, physical function, and kidney function trajectories during the first year after KT.

ABSTRACTPerformance‐based measures of frailty are associated with healthcare utilization after kidney transplantation (KT) but require in‐person assessment. A promising alternative is self‐reported frailty. The goal of this study was to examine the ability of performance‐based and self‐reported frailty measures to predict 30‐day rehospitalizations after KT. We conducted a prospective, observational cohort study involving 272 adults undergoing KT at Mayo Clinic in Minnesota, Florida, or Arizona. We simultaneously measured frailty before KT using the physical frailty phenotype (PFP), the short physical performance battery (SPPB), and self‐report (the Patient‐Reported Outcomes Measurement Information System [PROMIS] 4‐item physical function short form v2.0). Both the PFP and self‐reported frailty were independently associated with more than a 2‐fold greater odds of 30‐day rehospitalizations, while the SPPB was not. To our knowledge, this is the first study to assess the prognostic value of all three of the above frailty measures in patients undergoing KT. The PFP is more prognostic than the SPPB when assessing the risk of 30‐day rehospitalizations; self‐reported frailty can complement the PFP but not replace it. However, the 4‐item survey assessing self‐reported frailty represents a simple way to identify patients undergoing KT surgery who would benefit from interventions to lower the risk of rehospitalizations.