Determinants of the Evolution of Kidney Function With Age

Skeletal muscle mass and kidney function among Chinese older adults: a cross-sectional study

OBJECTIVES

To assess the association between kidney function and odds of having low skeletal muscle mass (LSMM) in Chinese adults on the basis of a community study.

DATA AND METHODS

In this cross-sectional study, we included 3726 Chinese older persons who participated in an ongoing prospective study, the China Health and Retirement Longitudinal Study(CHARLS). Fasting blood samples were collected in 2012 and analyzed for serum creatinine. Estimated glomerular filtration rate(eGFR) was computed using serum creatinine, gender, and age, according to the 2021 race-free Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI). We classified the target population into three categories according to eGFR (normal eGFR;90mL/min/1.73m2, mildly-impaired eGFR;60 to < 90 mL/min/1.73 m2, moderate to severve impaired eGFR;<60 mL/min/1.73 m2). BMI-adjusted muscle mass was used to measure skeletal muscle mass.The association between eGFR(per interquartile range(IQR) increment) and the risk of low skeletal muscle mass was assessed using logistic regression model.

RESULTS

Worsening renal function was associated with being high risk for LSMM after adjusting for potential confounders:the odds ratios (ORs) 95% confidence intervals (CIs) were 0.76 (95% CI = 0.63 - 0.88) for male, and [0.71, (0.61-0.82)]in female, p < 0.001. Specifically, male participants with mildly renal impairment were more prone to develop LSMM (multiadjusted OR, 1.43, 95% CI(0.92 to 2.09), p = 0.1) than femal(multiadjusted OR, 1.32, 95% CI(0.85 to 2.00), p = 0.2), the gender difference was not significant in severe renal dysfunction.However, there was a non-linear relationship between eGFR(per IQR increment) and risk of LSMM(eGFR/IQR =5.42, knot = 4 OR =1, p for non-linear <0.001).

CONCLUSIONS

Lower levels of eGFR had a high likelihood of being high risk for LSMM. Older male patients with mildly renal insufficiency are more likely to experience a decrease in skeletal muscle mass compared to female.

Impact of Percutaneous Cryoablation on Renal Function in Patients with Stage I Renal Cell Carcinoma: A Systematic Review and Meta-Analysis

PURPOSE

To assess the effect of cryoablation on renal function (measured by estimated glomerular filtration rate [eGFR] or serum creatinine) for treating Stage I renal cancer.

MATERIALS AND METHODS

The MEDLINE, Embase, and Cochrane Central Register of Controlled Trials databases were systematically searched from inception to May 1, 2023. Cohort studies that included data on change of eGFR and serum creatinine increase were included. Meta-analysis was performed by measuring the weighted mean difference and by fitting random-effect models.

RESULTS

Overall, 38 studies were included, comprising 3,202 participants. Percutaneous cryoablation was associated with an absolute eGFR reduction of -3.06 mL/min/1.73 m2 (95% CI, -4.12 to -2.01; P < .001) and serum creatinine increase of 0.05 mg/dL (95% CI, -0.02 to 0.11; P > .05). The weighted absolute mean difference of percutaneous cryoablation for treating Stage T1b renal cell carcinoma was estimated at -5.19 mL/min/1.73 m2 (95% CI, -11.1 to 0.72; P > .05). Lastly, when analyzing studies that included cohorts with solitary kidneys, the pooled weighted mean difference was estimated as -3.27 mL/min/1.73 m2 (95% CI, -6.79 to 0.25; P > .05).

CONCLUSIONS

Percutaneous cryoablation for Stage 1 renal cell carcinoma has minimal significant impact on renal function (measured by eGFR or serum creatinine). The same outcome was observed in patients with larger tumors (T1b) and those with solitary kidneys.

Impact of CYP2D6*2, CYP2D6*35, rs5758550, and related haplotypes on risperidone clearance in vivo

PURPOSE

The CYP2D6 gene exhibits significant polymorphism, contributing to variability in responses to drugs metabolized by CYP2D6. While CYP2D6*2 and CYP2D6*35 are presently designated as alleles encoding normal metabolism, this classification is based on moderate level evidence. Additionally, the role of the formerly called "enhancer" single nucleotide polymorphism (SNP) rs5758550 is unclear. In this study, the impacts of CYP2D6*2, CYP2D6*35 and rs5758550 on CYP2D6 activity were investigated using risperidone clearance as CYP2D6 activity marker.

METHODS

A joint parent-metabolite population pharmacokinetic model was used to describe 1,565 serum concentration measurements of risperidone and 9-hydroxyrisperidone in 512 subjects. Risperidone population clearance was modeled as the sum of a CYP2D6-independent clearance term and the partial clearances contributed from each individually expressed CYP2D6 allele or haplotype. In addition to the well-characterized CYP2D6 alleles (*3-*6, *9, *10 and *41), *2, *35 and two haplotypes assigned as CYP2D6*2-rs5758550G and CYP2D6*2-rs5758550A were evaluated.

RESULTS

Each evaluated CYP2D6 allele was associated with significantly lower risperidone clearance than the reference normal function allele CYP2D6*1 (p < 0.001). Further, rs5758550 differentiated the effect of CYP2D6*2 (p = 0.005). The haplotype-specific clearances for CYP2D6*2-rs5758550A, CYP2D6*2-rs5758550G and CYP2D6*35 were estimated to 30%, 66% and 57%, respectively, relative to the clearance for CYP2D6*1. Notably, rs5758550 is in high linkage disequilibrium (R2 > 0.85) with at least 24 other SNPs and cannot be assigned as a functional SNP.

CONCLUSION

CYP2D6*2 and CYP2D6*35 encode reduced risperidone clearance, and the extent of reduction for CYP2D6*2 is differentiated by rs5758550. Genotyping of these haplotypes might improve the precision of genotype-guided prediction of CYP2D6-mediated clearance.

Changes in estimated glomerular filtration rate in patients administered proton pump inhibitors: a single-center cohort study

Proton pump inhibitor (PPI) use may be associated with renal dysfunction. Renal dysfunction in PPI users requires evaluation of development and progression risks simultaneously, using estimated glomerular filtration rate (eGFR) slope, which indicates changes in eGFR per year. To the best of our knowledge, no studies have evaluated eGFR slope in PPI users. This study investigated the association between PPI use and renal dysfunction using eGFR slope. A single-center cohort study was conducted using the health records data at Hamamatsu University Hospital in Japan. Participants were defined as first users of acid-suppressing drugs (PPIs or Histamine H2 receptor antagonists (H2RAs)) from 2010 to 2021 and continuously prescribed for  ≥ 90 days. The H2RA group was used for the propensity-score matching (PSM) to the PPI group to minimize the effects of confounders. The eGFR slope was estimated using a linear mixed effects model. Participants were stratified by baseline eGFR and age, respectively, as subgroup analyses. A total of 4,649 acid-suppressing drug users met the inclusion criteria, including 950 taking H2RAs and 3,699 PPIs. After PSM, 911 patients were assigned to each group. The eGFR slopes of the PPI and H2RA users were -4.75 (95% CI: -6.29, -3.20) and -3.40 (-4.38, -2.42), respectively. The difference between the groups was not significant. Significant declines in eGFR were observed with PPIs with baseline eGFR ≥ 90 and age  < 65. PPI use for  ≥ 90 days may hasten eGFR decline compared to H2RA use, especially in patients with eGFR  ≥ 90 or age  < 65.

Chronic kidney disease and the global public health agenda: an international consensus

Early detection is a key strategy to prevent kidney disease, its progression and related complications, but numerous studies show that awareness of kidney disease at the population level is low. Therefore, increasing knowledge and implementing sustainable solutions for early detection of kidney disease are public health priorities. Economic and epidemiological data underscore why kidney disease should be placed on the global public health agenda - kidney disease prevalence is increasing globally and it is now the seventh leading risk factor for mortality worldwide. Moreover, demographic trends, the obesity epidemic and the sequelae of climate change are all likely to increase kidney disease prevalence further, with serious implications for survival, quality of life and health care spending worldwide. Importantly, the burden of kidney disease is highest among historically disadvantaged populations that often have limited access to optimal kidney disease therapies, which greatly contributes to current socioeconomic disparities in health outcomes. This joint statement from the International Society of Nephrology, European Renal Association and American Society of Nephrology, supported by three other regional nephrology societies, advocates for the inclusion of kidney disease in the current WHO statement on major non-communicable disease drivers of premature mortality.

Renal Proximal Tubule Cell-specific Megalin Deletion Does Not Affect Atherosclerosis But Induces Tubulointerstitial Nephritis in Mice Fed Western Diet

Background

Pharmacological inhibition of megalin (also known as low-density lipoprotein receptor-related protein 2: LRP2) attenuates atherosclerosis in hypercholesterolemic mice. Since megalin is abundant in renal proximal tubule cells (PTCs), the purpose of this study was to determine whether PTC-specific deletion of megalin reduces hypercholesterolemia-induced atherosclerosis in mice.

Methods

Female Lrp2 f/f mice were bred with male Ndrg1-Cre ERT2 +/0 mice to develop PTC-LRP2 +/+ and -/- littermates. To study atherosclerosis, all mice were to bred to an LDL receptor -/- background and fed a Western diet to induce atherosclerosis.

Results

PTC-specific megalin deletion did not attenuate atherosclerosis in LDL receptor -/- mice in either sex. Serendipitously, we discovered that PTC-specific megalin deletion led to interstitial infiltration of CD68+ cells and tubular atrophy. The pathology was only evident in male PTC-LRP2 -/- mice fed the Western diet, but not in mice fed a normal laboratory diet. Renal pathologies were also observed in male PTC-LRP2 -/- mice in an LDL receptor +/+ background fed the same Western diet, demonstrating that the renal pathologies were dependent on diet and not hypercholesterolemia. By contrast, female PTC-LRP2 -/- mice had no apparent renal pathologies. In vivo multiphoton microscopy demonstrated that PTC-specific megalin deletion dramatically diminished albumin accumulation in PTCs within 10 days of Western diet feeding. RNA sequencing analyses demonstrated the upregulation of inflammation-related pathways in kidney.

Conclusions

PTC-specific megalin deletion does not affect atherosclerosis, but leads to tubulointerstitial nephritis in mice fed Western diet, with severe pathologies in male mice.

Has the time come for age-adapted glomerular filtration rate criteria to define chronic kidney disease: how soon is now?

PURPOSE OF REVIEW

The conventional definition of chronic kidney disease (CKD) primarily relies on the identification of albuminuria or a decline in estimated glomerular filtration rate (eGFR). For many years, a straightforward eGFR threshold of <60 ml/min/1.73 m 2 has been widely adopted as the standard for defining CKD. Nonetheless, this criterion fails to consider the natural aging process of the kidney, and this oversight may affect the accurate diagnosis of kidney disease particularly at the extremes of age.

RECENT FINDINGS

The fixed eGFR threshold of <60 ml/min/1.73 m 2 for defining CKD misses crucial opportunities for risk prevention. Studies have revealed that the eGFR threshold at which the risks for adverse long-term health outcomes such as mortality, cardiovascular events, and kidney failure begin to rise varies substantially by age. Specifically, this threshold is lower for the elderly and higher for young adults. Consequently, this results in the over-diagnosis of kidney disease in the elderly and the under-diagnosis of kidney disease in young adults.

SUMMARY

To address these limitations of the current CKD definition, we discuss a number of proposed age-adapted eGFR criteria and weigh their pros and cons against the current, simple, and universally accepted approach.

Plasma brain-derived tau is an amyloid-associated neurodegeneration biomarker in Alzheimer's disease

Staging amyloid-beta (Aβ) pathophysiology according to the intensity of neurodegeneration could identify individuals at risk for cognitive decline in Alzheimer's disease (AD). In blood, phosphorylated tau (p-tau) associates with Aβ pathophysiology but an AD-type neurodegeneration biomarker has been lacking. In this multicenter study (n = 1076), we show that brain-derived tau (BD-tau) in blood increases according to concomitant Aβ ("A") and neurodegeneration ("N") abnormalities (determined using cerebrospinal fluid biomarkers); We used blood-based A/N biomarkers to profile the participants in this study; individuals with blood-based p-tau+/BD-tau+ profiles had the fastest cognitive decline and atrophy rates, irrespective of the baseline cognitive status. Furthermore, BD-tau showed no or much weaker correlations with age, renal function, other comorbidities/risk factors and self-identified race/ethnicity, compared with other blood biomarkers. Here we show that blood-based BD-tau is a biomarker for identifying Aβ-positive individuals at risk of short-term cognitive decline and atrophy, with implications for clinical trials and implementation of anti-Aβ therapies.

Urinary Prostaglandin E2 Excretion and the Risk of Cardiovascular and Kidney Disease

BACKGROUND

Inhibition of prostaglandin synthesis by nonsteroidal anti-inflammatory drugs is associated with cardiovascular mortality and kidney disease. This study hypothesizes that urinary prostaglandin E2 (PGE2) and PGE2 metabolite (PGEM) excretions are markers of cardiovascular and kidney health, because they reflect both systemic and kidney-derived PGE2 production.

METHODS AND RESULTS

PGE2 and PGEM were measured in spot urine samples from 2291 participants (≥55 years old) of the population-based Rotterdam Study. Urinary PGE2 and PGEM excretions were analyzed using linear regression analyses to identify cross-sectional associations with cardiovascular risk factors and baseline estimated glomerular filtration rate (eGFR). Longitudinal associations with cardiovascular mortality and kidney outcomes (eGFR <60 or <45 mL/min per 1.73 m2 and the composite outcome 40% eGFR loss or kidney failure) were assessed with Cox regression. Urinary PGE2 and PGEM excretions were higher with increasing age, lower eGFR, smoking, diabetes, and albuminuria. A 2-fold higher urinary PGE2 and PGEM excretion was associated with a higher risk of cardiovascular mortality (28 825 patient-years; 160 events; PGE2 hazard ratio [HR], 1.27, [95% CI, 1.06-1.54]; PGEM HR, 1.36 [95% CI, 1.10-1.67]). Higher PGE2 excretions were also associated with a higher risk of incident eGFR <60 mL/min per 1.73 m2 (31 530 person-years; 691 events; HR, 1.13 [95% CI, 1.02-1.25]) with similar HRs for the other kidney outcomes.

CONCLUSIONS

Urinary PGE2 and PGEM excretions are novel markers for the presence and progression of cardiovascular and kidney disease. Future studies should address whether these associations are causal and can be targeted to improve cardiovascular and kidney outcomes.

The Rotterdam Study. Design update and major findings between 2020 and 2024

The Rotterdam Study is a population-based cohort study, started in 1990 in the district of Ommoord in the city of Rotterdam, the Netherlands, with the aim to describe the prevalence and incidence, unravel the etiology, and identify targets for prediction, prevention or intervention of multifactorial diseases in mid-life and elderly. The study currently includes 17,931 participants (overall response rate 65%), aged 40 years and over, who are examined in-person every 3 to 5 years in a dedicated research facility, and who are followed-up continuously through automated linkage with health care providers, both regionally and nationally. Research within the Rotterdam Study is carried out along two axes. First, research lines are oriented around diseases and clinical conditions, which are reflective of medical specializations. Second, cross-cutting research lines transverse these clinical demarcations allowing for inter- and multidisciplinary research. These research lines generally reflect subdomains within epidemiology. This paper describes recent methodological updates and main findings from each of these research lines. Also, future perspective for coming years highlighted.

Circulating metabolites associated with kidney function decline and incident CKD: a multi-platform population-based study

Background

Investigation of circulating metabolites associated with kidney function and chronic kidney disease (CKD) risk could enhance our understanding of underlying pathways and identify new biomarkers for kidney function.

Methods

We selected participants from the population-based Rotterdam Study with data on circulating metabolites and estimated glomerular filtration rate based on serum creatinine (eGFRcreat) available at the same time point. Data on eGFR based on serum cystatin C (eGFRcys) and urine albumin-to-creatinine ratio (ACR) were also included. CKD was defined as eGFRcreat <60 ml/min per 1.73 m2. Data on circulating metabolites (ntotal = 1381) was obtained from the Nightingale and Metabolon platform. Linear regression, linear mixed, and Cox proportional-hazards regression analyses were conducted to study the associations between metabolites and kidney function. We performed bidirectional two-sample Mendelian randomization analyses to investigate causality of the identified associations.

Results

We included 3337 and 1540 participants with data from Nightingale and Metabolon, respectively. A total of 1381 metabolites (243 from Nightingale and 1138 from Metabolon) were included in the analyses. A large number of metabolites were significantly associated with eGFRcreat, eGFRcys, ACR, and CKD, including 16 metabolites that were associated with all four outcomes. Among these, C-glycosyltryptophan (HR 1.50, 95%CI 1.31;1.71) and X-12026 (HR 1.46, 95%CI 1.26;1.68) were most strongly associated with CKD risk. We revealed sex differences in the associations of 11-ketoetiocholanolone glucuronide and 11-beta-glucuronide with the kidney function assessments. No causal associations between the identified metabolites and kidney function were observed.

Conclusion

Our study indicates that several circulating metabolites are associated with kidney function which are likely to have potential as biomarkers, rather than as molecules involved in the pathophysiology of kidney function decline.

Differences in the epidemiology, management and outcomes of kidney disease in men and women

Improved understanding of differences in kidney disease epidemiology, management and outcomes in men and women could help nephrologists to better meet the needs of their patients from a sex- and gender-specific perspective. Evidence of sex differences in the risk and outcomes of acute kidney injury is mixed and dependent on aetiology. Women have a higher prevalence of chronic kidney disease (CKD) stages 3-5 than men, whereas men have a higher prevalence of albuminuria and hence CKD stages 1-2. Men show a faster decline in kidney function, progress more frequently to kidney failure and have higher mortality and risk of cardiovascular disease than women. However, the protective effect of female sex is reduced with CKD progression. Women are less likely than men to be aware of, screened for and diagnosed with CKD, started on antiproteinuric medication and referred to nephrologist care. They also consistently report a poorer health-related quality of life and a higher symptom burden than men. Women experience greater barriers than men to access the waiting list for kidney transplantation, particularly with respect to older age and obesity. However, women also have longer survival than men after transplantation, which may partly explain the comparable prevalence of transplantation between the sexes.

Trajectories of kidney function and risk of mortality

BACKGROUND

We aimed to identify patterns within the rate of kidney function decline, determinants of these patterns and their association with all-cause mortality risk in the general population.

METHODS

Participants aged ≥ 45 years with at least one assessment of creatinine-based estimated glomerular filtration rate (eGFR) taken between 1997 and 2018 were selected from a population-based cohort study. Analyses were performed using several distinct latent class trajectory modelling methods. Cumulative incidences were calculated with 45 years of age as the starting point.

RESULTS

In 12 062 participants (85 922 eGFR assessments, mean age 67.0 years, 58.7% women, median follow-up 9.6 years), four trajectories of eGFR change with age were identified: slow eGFR decline [rate of change in mL/min/1.73 m2 per year (RC), -0.9; 95% CI, -0.9 to -0.9; reference group], intermediate eGFR decline (RC, -2.5; 95% CI, -2.7 to -2.5) and fast eGFR decline (RC, -4.3; 95% CI, -4.4 to -4.1), and an increase/stable eGFR (RC, 0.3; 95% CI, 0.3 to 0.4). Women were more likely to have an increase/stable eGFR [odds ratio (OR), 1.94; 95% CI, 1.53 to 2.46] whereas men were more likely to have a fast eGFR decline (OR, 1.86; 95% CI, 1.33 to 2.60). Participants with diabetes, cardiovascular disease (CVD) or hypertension were more likely to have an intermediate or fast eGFR decline. All-cause mortality risks (cumulative incidence at age of 70 years) were 32.3% (95% CI, 21.4 to 47.9, slow eGFR decline), 6.7% (95% CI, 3.5 to 12.4, intermediate eGFR decline), 68.8% (95% CI, 44.4 to 87.8, fast eGFR decline) and 9.5% (95% CI, 5.5 to 15.7, increase/stable eGFR).

CONCLUSION

Sex, hypertension, diabetes and CVD were identified as trajectory membership determinants. Having fast eGFR decline was associated with the highest risk of all-cause mortality, highlighting the need for extensive monitoring and prevention of kidney function decline in individuals at risk of having fast eGFR decline.

Parenchymal volume analysis to assess longitudinal functional decline following partial nephrectomy

OBJECTIVE

To identify factors associated with longitudinal ipsilateral functional decline after partial nephrectomy (PN).

PATIENTS AND METHODS

Of 1140 patients managed with PN (2012-2014), 349 (31%) had imaging/serum creatinine levels pre-PN, 1-12 months post-PN (new baseline), and >3 years later necessary for inclusion. Parenchymal-volume analysis was used to determine split renal function. Patients were grouped as having significant renal comorbidity (CohortSRC : diabetes mellitus with insulin-dependence or end-organ damage, refractory hypertension, or severe pre-existing chronic kidney disease) vs not having significant renal comorbidity (CohortNoSRC ) preoperatively. Multivariable regression was used to identify predictors of annual ipsilateral parenchymal atrophy and functional decline relative to new baseline values post-PN, after the kidney had healed.

RESULTS

The median follow-up was 6.3 years with 87/226/36 patients having cold/warm/zero ischaemia. The median cold/warm ischaemia times were 32/22 min. Overall, the median tumour size was 3.0 cm. The preoperative glomerular filtration rate (GFR) and new baseline GFR (NBGFR) were 81 and 71 mL/min/1.73 m2 , respectively. After establishment of the NBGFR, the median loss of global and ipsilateral function was 0.7 and 0.4 mL/min/1.73 m2 /year, respectively, consistent with the natural ageing process. Overall, the median ipsilateral parenchymal atrophy was 1.2 cm3 /year and accounted for a median of 53% of the annual functional decline. Significant renal comorbidity, age, and warm ischaemia were independently associated with ipsilateral parenchymal atrophy (all P < 0.01). Significant renal comorbidity and ipsilateral parenchymal atrophy were independently associated with annual ipsilateral functional decline (both P < 0.01). Annual median ipsilateral parenchymal atrophy and functional decline were both significantly increased for CohortSRC compared to CohortNoSRC (2.8 vs 0.9 cm3 , P < 0.01 and 0.90 vs 0.30 mL/min/1.73 m2 /year, P < 0.01, respectively).

CONCLUSIONS

Longitudinal renal function following PN generally follows the normal ageing process. Significant renal comorbidities, age, warm ischaemia, and ipsilateral parenchymal atrophy were the most important predictors of ipsilateral functional decline following establishment of NBGFR.

Structural and physiological changes of the kidney with age and its impact on chronic conditions and COVID-19

The kidney is an essential organ that removes waste products, balances the body's fluids, releases hormones that regulate blood pressure, produces an active form of vitamin D, promotes healthy bones, and controls the production of red blood cells. Structural and functional abnormalities occur in kidney with age. Alterations in kidney structure are based on physiological functions and environmental pressures. Variations in its structure across vertebrates are primarily due to the nature of alterations in number, complexity, arrangement, and location of the kidney tubules. Globally, individuals aged 65 and older are part of the fastest expanding population demographic, and as a result, a greater number of older patients are receiving a diagnosis of impaired renal function. The purpose of our mini-review is to summarize recent findings of the structural and functional differences between the normal and aging kidney, examine the evolutionary biology of the kidney across species, and demonstrate the role of aging in conditions such as diabetes, chronic kidney disease, and hypertension, along with their impact on SARS-CoV-2. Additional aims include discussing the potential therapeutic strategies to treat aged individuals with kidney health issues and how the impact of a healthy lifestyle, diet, and exercise can improve health conditions with aged kidneys.

Sex Differences in the Association Between Serum Testosterone and Kidney Function in the General Population

Introduction

Testosterone might prevent kidney function decline, although evidence is limited in men and lacking in women from the general population. We investigated the association between serum testosterone and kidney function in men and women from a large population-based cohort study.

Methods

Participants aged ≥45 years with available measurements of serum testosterone, sex hormone-binding globulin (SHBG), creatinine, and cystatine C were included. Assessments of kidney function included baseline assessments of the estimated glomerular filtration rate (eGFR) based on serum creatinine (eGFRcreat) or serum cystatin C (eGFRcys), and the urine albumin-to-creatinine ratio (ACR), and repeated assessments of eGFRcreat. Linear regression and linear mixed models were used to assess the associations of serum free and total testosterone with kidney function, stratified for sex.

Results

A total of 4095 men and 5389 women (mean age 65.2 years) were included. In men, higher free testosterone was associated with lower eGFRcreat (beta -0.63, 95% confidence interval [CI]: -1.05; -0.21), higher eGFRcys (beta 0.56, 95% CI: 0.07; 1.05), and lower ACR (beta -0.25, 95% CI: -0.35; -0.16) at baseline. Higher total testosterone was associated with higher baseline and follow-up eGFRcreat, and with lower eGFRcreat when additionally adjusted for SHBG. In women, higher free testosterone was associated with lower baseline eGFRcreat and eGFRcys (beta -1.03, 95% CI: -1.36; -0.71; beta -1.07, 95% CI: -1.44; -0.70; respectively) and lower eGFRcreat over time (beta -0.78, 95% CI: -1.10; -0.46), but not with ACR.

Conclusions

eGFRcys might be a better parameter than eGFRcreat for the association of testosterone with kidney function, although further studies investigating this are needed. Furthermore, we identified sex differences in the association between testosterone and kidney function, with a positive association in men and a negative association in women.

Associations between modest reductions in kidney function and adverse outcomes in young adults: retrospective, population based cohort study

OBJECTIVE

To study age specific associations of modest reductions in estimated glomerular filtration rate (eGFR) with adverse outcomes.

DESIGN

Retrospective, population based cohort study.

SETTING

Linked healthcare administrative datasets in Ontario, Canada.

PARTICIPANTS

Adult residents (18-65 years) with at least one outpatient eGFR value (categorized in 10 unit increments from 50 mL/min/1.73m2 to >120 mL/min/1.73m2), with no history of kidney disease.

MAIN OUTCOME MEASURES

eGFRs and hazard ratios of composite adverse outcome (all cause mortality, any cardiovascular event, and kidney failure) stratified by age (18-39 years, 40-49 years, and 50-65 years), and relative to age specific eGFR referents (100-110 mL/min/1.73m2) for ages 18-39 years, 90-100 for 40-49 years, 80-90 for 50-65 years).

RESULTS

From 1 January 2008 to 31 March 2021, among 8 703 871 adults (mean age 41.3 (standard deviation 13.6) years; mean index eGFR 104.2 mL/min/1.73m2 (standard deviation 16.1); median follow-up 9.2 years (interquartile range 5.7-11.4)), modestly reduced eGFR measurements specific to age were recorded in 18.0% of those aged 18-39, 18.8% in those aged 40-49, and 17.0% in those aged 50-65. In comparison with age specific referents, adverse outcomes were consistently higher by hazard ratio and incidence for ages 18-39 compared with older groups across all eGFR categories. For modest reductions (eGFR 70-80 mL/min/1.73m2), the hazard ratio for ages 18-39 years was 1.42 (95% confidence interval 1.35 to 1.49), 4.39 per 1000 person years; for ages 40-49 years was 1.13 (1.10 to 1.16), 9.61 per 1000 person years; and for ages 50-65 years was 1.08 (1.07 to 1.09), 23.4 per 1000 person years. Results persisted for each individual outcome and in many sensitivity analyses.

CONCLUSIONS

Modest eGFR reductions were consistently associated with higher rates of adverse outcomes. Higher relative hazards were most prominent and occurred as early as eGFR <80 mL/min/1.73m2 in younger adults, compared with older groups. These findings suggest a role for more frequent monitoring of kidney function in younger adults to identify individuals at risk to prevent chronic kidney disease and its complications.

Dairy products and kidney function decline after myocardial infarction: A prospective analysis in the Alpha Omega Cohort

BACKGROUND & AIMS

Population-based studies have shown both beneficial and neutral associations between dairy consumption and kidney function outcomes. We investigated the association between dairy products and kidney function decline in drug-treated post-myocardial infarction (MI) patients.

METHODS

We analysed data of 2169 post-MI patients (aged 60-80 years, 81% male) of the Alpha Omega Cohort. Dietary data were collected at baseline (2002-2006) using a validated 203-item food frequency questionnaire. The 2021 Chronic Kidney Disease Epidemiology (CKD-EPI) equation was used to estimate 40-months change in creatinine-cystatin C based glomerular filtration rate (eGFR_cr-cysC, mL/min per 1.73 m²). Beta coefficients and 95% confidence intervals (CIs) for dairy products in relation to annual eGFR_cr-cysC change were obtained from multivariable linear regression, adjusted for age, sex, energy intake, and other lifestyle and dietary factors.

RESULTS

Baseline energy-adjusted median intakes were 64 g/day for total milk, 20 g/day for hard cheeses, 18 g/day for plain yogurt, and 70 g/day for dairy desserts. Mean ± SD eGFR_cr-cysC was 84 ± 20 (13% with CKD), and annual eGFR_cr-cysC change was -1.71 ± 3.85. In multivariable models, high vs. low intakes of total milk, cheese, and dairy desserts were not associated with annual eGFR_cr-cysC change (β_{total milk}: -0.21 [-0.60; 0.19], β_cheese: -0.08 [-0.52; 0.36], β_{dairy desserts}: -0.24 [-0.72; 0.24]). High vs. low intake of yogurt was adversely associated with annual eGFR_cr-cysC change (β_{total yogurt}: -0.50 [-0.91;-0.09]), but subsequent spline analyses showed no clear dose-response association.

CONCLUSIONS

Intakes of milk, cheese or dairy desserts were not associated with a delayed kidney function decline after MI. The observed adverse association for yogurt should be interpreted with caution. Our findings require confirmation in other cohorts of coronary heart disease patients.

Quantification of Epistemic Capacity and Physical Frailty in Chronic Kidney Disease: Koch's Disease Co-infection

Background Chronic kidney disease (CKD) and tuberculosis (TB) co-infection devastates the affected individual physically and psychologically. Moreover, poor immune status and mental turmoil worsen cognition and quality of life. Hence, studying the cognitive function and quality of life among such patients is necessary. This study aimed to determine the changes in mini-mental state examination (MMSE) score and general health questionnaire (GHQ-12) score at six months from baseline. Methodology This prospective, observational study was conducted at Sriram Chandra Bhanja Medical College and Hospital, India, from February 2020 to December 2021. A total of 40 patients with stage 3-4 CKD and pulmonary TB were assessed with MMSE and GHQ-12 scales at baseline, two, and six months. The study population was grouped as ≤50 and >50 years of age. We used R software (version 4.1.1) for data analysis. Results In total, 40 (69%) of the 58 enrolled participants completed this study. The mean age of the study population was 50.93 ± 9.83 years. The baseline MMSE scores (≤50 years: 20.8 ± 2.1, >50 years: 20.1 ± 1.7, p = 0.17) were increased (≤50 years: 25.4 ± 1.8, >50 years: 22.4 ± 1.6, p = 0.08) at six months. The baseline GHQ-12 scores (≤50 years: 22.8 ± 2.6, >50 years: 23.1 ± 2.8, p = 0.56) were reduced (≤50 years: 17.9 ± 1.9, >50 years: 20.3 ± 2.3, p = 0.14) at six months. Conclusions The study participants' cognitive function and quality of life improved after six months of modified antitubercular drugs. Nevertheless, the intergroup differences were not statistically significant.

Prognostic significance of albuminuria in elderly of various ages with diabetes

It remains uncertain whether albuminuria can identify elderly patients with diabetes at a high risk of incident end-stage kidney disease (ESKD) or mortality. 3065 patients (aged ≥ 65 years) with type 2 diabetes were included. We examined the association between albuminuria stages (normoalbuminuria, A1; microalbuminuria, A2; and macroalbuminuria, A3) and the risk of incident ESKD and all-cause mortality for each age group (65-69, 70-74, and ≥ 75 years). A2 and A3 were observed in 25.5% and 9.4% of the subjects, respectively. For A1, A2, and A3, the probabilities of ESKD at 8 years were 1.0%, 6.3%, and 29.7% (P < 0.001 for all), and the all-cause mortality was 13.1%, 27.4%, and 31.7% (P < 0.001 for A1 vs A2, P < 0.001 for A1 vs A3), respectively. Albuminuria stages were independently associated with an increased risk of ESKD [fully adjusted hazard ratios (HR): 3.650 (1.987-6.702) for A2, 10.404 (5.706-18.972) for A3 vs. A1]. The HRs of all-cause mortality were 1.742 (1.411-2.153) for A2 and 1.810 (1.344-2.441) for A3. The associations between albuminuria stages and the risk of ESKD and all-cause mortality were consistent across all age groups. Even microalbuminuria is also a risk factor for incident ESKD and mortality in elderly patients with diabetes.

Long-Term Renal Function Following Renal Cancer Surgery: Historical Perspectives, Current Status, and Future Considerations

Knowledge of functional recovery after partial (PN) and radical nephrectomy for renal cancer has advanced considerably, with PN now established as the reference standard for most localized renal masses. However, it is still unclear whether PN provides an overall survival benefit in patients with a normal contralateral kidney. While early studies seemingly demonstrated the importance of minimizing warm-ischemia time during PN, multiple new investigations over the last 10 years have proven that parenchymal mass lost is the most important predictor of new baseline renal function. Minimizing loss of parenchymal mass during resection and reconstruction is the most important controllable aspect of long-term post-operative renal function preservation.

Magnesium in Kidney Function and Disease-Implications for Aging and Sex-A Narrative Review

Magnesium (Mg) has a vital role in the human body, and the kidney is a key organ in the metabolism and excretion of this cation. The objective of this work is to compile the available evidence regarding the role that Mg plays in health and disease, with a special focus on the elderly population with chronic kidney disease (CKD) and the eventual sex differences. A narrative review was carried out by executing an exhaustive search in the PubMed, Scopus, and Cochrane databases. Ten studies were found in which the role of Mg and sex was evaluated in elderly patients with CKD in the last 10 years (2012-2022). The progression of CKD leads to alterations in mineral metabolism, which worsen as the disease progresses. Mg can be used as a coadjuvant in the treatment of CKD patients to improve glomerular filtration, but its use in clinical applications needs to be further characterized. In conclusion, there's a need for well-designed prospective clinical trials to advise and standardize Mg supplementation in daily clinical practice, taking age and sex into consideration.

Association of habitual coffee consumption and kidney function: A prospective analysis in the Rotterdam Study

BACKGROUND & AIMS

Population-based studies have suggested a protective effect of coffee against development of chronic kidney disease (CKD), possibly through coffee's anti-inflammatory and antioxidant compounds. Studies on coffee and kidney function decline in the general population are scarce. We studied associations of habitual coffee consumption with repeated assessments of estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (ACR).

METHODS

We used data from 7,914 participants of the population-based Rotterdam Study. Baseline coffee consumption data (cups/day) were obtained from home interviews and validated food frequency questionnaires (1997-2008). Repeated assessments of eGFR (ml/min per 1.73 m², 1997-2014) were calculated according to the creatinine-based CKD Epidemiology Collaboration equation of 2012. Repeated assessments of urinary albumin and creatinine were used to estimate ACR (mg/g, 2006-2014). Data were analyzed by applying linear mixed models, adjusted for sociodemographic, lifestyle and dietary factors, and cardiovascular disease risk factors. Predefined subgroup analyses were performed stratified by CKD risk factors.

RESULTS

Participants' mean (SD) baseline age was 66 (10) years, 57% were women and median [IQR] coffee consumption was 3.0 [2.0, 5.0] cups/day. Those drinking more coffee were more likely to smoke, and to have type 2 diabetes (T2D) and obesity. Mean eGFR was 79 (15) ml/min per 1.73 m². In the total study population, coffee was not associated with longitudinal eGFR during a median of 5.4 years of follow-up (β = 0.04 ml/min per 1.73 m² per one cup/day [95% CI: -0.10,0.18]). However, among those aged >70 years, one additional coffee cup/day was associated with on average 0.84 (0.51,1.18) ml/min per 1.73 m² higher longitudinal eGFR. Among obese participants this estimate was 0.32 (0.01,0.63). A protective trend was also observed among former smokers (0.17 [-0.03,0.39]) and those with T2D (0.42 [-0.05,0.88]). Coffee was not associated with longitudinal ACR (0.01 mg/ml [-0.01,0.02]).

CONCLUSION

While coffee was not associated with eGFR and ACR in the total population, more coffee consumption was associated with higher longitudinal eGFR among those at higher risk for CKD, i.e., among those aged 70+ and obese participants. These findings require confirmation in other prospective cohort studies.

Structural and Functional Changes in Aging Kidneys

The renal condition is one of the crucial predictors of longevity; therefore, early diagnosis of any dysfunction plays an important role. Kidneys are highly susceptible to the aging process. Unfavorable conditions may lead to a significant disturbance of the body's homeostasis. Apart from physiological changes, there are some conditions such as hypertension, diabetes or obesity which contribute to the acceleration of the aging process. A determination of macroscopic and microscopic changes is essential for assessing the progression of aging. With age, we observe a decrease in the volume of renal parenchyma and an increase in adipose tissue in the renal sinuses. Senescence may also be manifested by the roughness of the kidney surface or simple renal cysts. The main microscopic changes are a thickening of the glomerular basement membrane, nephrosclerosis, an accumulation of extracellular matrix, and mesangial widening. The principal aspect of stopping unfavorable changes is to maintain health. Studies have shown many useful ways to mitigate renal aging. This review is focused especially on medications such as renin-angiotensin-aldosterone system blockers or resveratrol, but even eating habits and lifestyle.

Long-term follow-up of patients undergoing renal sympathetic denervation

OBJECTIVES

Renal denervation (RDN) proved to significantly lower blood pressure (BP) at 2-6 months in patients on and off antihypertensive drugs. Given a lack of longer-term follow-up data, our aim was to assess the safety and efficacy of RDN up to five years taking into account antihypertensive drug regimen changes over time.

METHODS

In the present single-center study, patients underwent RDN for (therapy resistant) hypertension. Patients underwent protocolized yearly follow-up out to five years. Data were collected on 24-h ambulatory BP and office BP monitoring, renal function, antihypertensive drug regimen, and safety events, including non-invasive renal artery imaging at 6/12 months. Efficacy analyses were performed using linear mixed-effects models.

RESULTS

Seventy-two patients with mean age 63.3 ± 9.5 (SD) years (51% female) were included. Median follow-up time was 3.5 years and Clark's Completeness Index was 72%. Baseline ambulatory daytime BP was 146.1/83.7 ± 17.4/12.2 mmHg under a mean number of 4.9 ± 2.7 defined daily doses (DDD). At five years, ambulatory daytime systolic BP as calculated from the mixed model was 120.8 (95% CI 114.2-127.5) mmHg and diastolic BP was 73.3 (95% CI 69.4-77.3) mmHg, implying a reduction of -20.9/-8.3 mmHg as compared to baseline estimates (p < 0.0001). The number of DDDs remained stable over time (p = 0.87). No procedure-related major adverse events resulting in long-term consequences were observed.

CONCLUSIONS

The BP-lowering effect of RDN was safely maintained at least five years post-procedure as reflected by a significant decrease in ambulatory daytime BP in the absence of escalating antihypertensive drug therapy over time.

Aging and hypertension in kidney function decline: A 10 year population-based study

Background

Aging is associated with a physiological decline in kidney function (KFD). In this study, we aimed to describe the impact of age on the rate of KFD and its interplay with risk factors for chronic kidney disease (CKD), considering mainly hypertension (HT), in the general population.

Materials and methods

Participants of European descent, aged 35-75, were recruited from a populational cohort in Lausanne, Switzerland. Participants with a 10 year follow-up were selected. KFD was defined as the difference in estimated glomerular filtration rate (eGFR) between baseline and follow-up, divided by the observation period. Multivariate linear regressions were used with KFD as the outcome and age as the main predictor. HT was tested as a modifying factor.

Results

We included 4,163 participants with mean age 52.2 ± 10.4, 44.7% men, 31.9% HT, and 5.0% diabetics. Mean baseline eGFR was 85.9 ± 14.6 ml/min/1.73 m². Mean KFD was -0.49 ± 1.08 ml/min/1.73 m² per year with 70% of participants decreasing their eGFR during follow-up. The relationship between age and KFD was non-linear and age was divided in tertiles. Old participants had faster rates of KFD as compared to young and middle-age participants (p < 0.001). A significant interaction was found between age and HT on KFD prediction (p < 0.001). In HT participants, KFD was significantly different across tertiles of age (p < 0.001). On contrary, KFD was not different across tertiles of age in non-HT participants.

Conclusion

A physiological KFD is present over time in the general population. Age contributes non-linearly to the rate of this decline with older subjects declining the fastest. The presence of HT is a major contributing factor in this setting as KFD worsened with age only in hypertensive participants. Thus, HT represents an important pathological factor aggravating the age-related physiological decline in eGFR in the general population.

Sex Differences in Age-Related Loss of Kidney Function

BACKGROUND

CKD is more prevalent in women, but more men receive kidney replacement therapy for kidney failure. This apparent contradiction is not well understood.

METHODS

We investigated sex differences in the loss of kidney function and whether any sex disparities could be explained by comorbidity or CKD risk factors. In the Renal Iohexol Clearance Survey (RENIS) in northern Europe, we recruited 1837 persons (53% women, aged 50-62 years) representative of the general population and without self-reported diabetes, CKD, or cardiovascular disease. Participants' GFR was measured by plasma iohexol clearance in 2007-2009 (n=1627), 2013-2015 (n=1324), and 2018-2020 (n=1384). At each study visit, healthy persons were defined as having no major chronic diseases or risk factors for CKD. We used generalized additive mixed models to assess age- and sex-specific GFR decline rates.

RESULTS

Women had a lower GFR than men at baseline (mean [SD], 90.0 [14.0] versus 98.0 [13.7] ml/min per 1.73 m2; P<0.001). The mean GFR change rate was -0.96 (95% confidence interval [CI], -0.88 to -1.04) ml/min per 1.73 m2 per year in women and -1.20 (95% confidence interval [CI], -1.12 to -1.28) in men. Although the relationship between age and GFR was very close to linear in women, it was curvilinear in men, with steeper GFR slopes at older ages (nonlinear effect; P<0.001). Healthy persons had a slower GFR decline, but health status did not explain the sex difference in the GFR decline.

CONCLUSION

Among middle-aged and elderly individuals in the general population, decline in the mean GFR in women was slower than in men, independent of health status.

Bidirectional Association Between Kidney Function and Atrial Fibrillation: A Population-Based Cohort Study

Background Consensus lacks concerning a bidirectional association between kidney function and atrial fibrillation (AF), but this is crucial information for prevention/treatment efforts for both chronic kidney disease and AF. Therefore, we investigated the bidirectional association between kidney function and AF. Methods and Results This study was a prospective cohort study including 9228 participants (mean age, 64.9 years; 57.2% women) with information on kidney function (estimated glomerular filtration rate [eGFR] based on serum creatinine [eGFRcreat], cystatin C [eGFRcys], or both [eGFRcreat-cys], and urine albumin-to-creatinine ratio) and AF. Reduced kidney function was defined as eGFRcreat <60 mL/min per 1.73 m². Cox proportional-hazards, logistic regression, linear mixed, and joint models were used to investigate the association of kidney function with AF and vice versa. During follow-up (median of 8.0 years), 780 events of incident AF occurred. Lower eGFRcys and eGFRcreat-cys were associated with increased AF risk (hazard ratio [HR], 1.08 [95% CI, 1.03-1.14] and HR, 1.07 [95% CI, 1.01-1.14], respectively, per 10 mL/min per 1.73 m² eGFR decrease). For eGFRcys and eGFRcreat-cys, 10-year cumulative incidence of AF was 16% (eGFR <60) and 6% (eGFR ≥60). Prevalent AF (versus no prevalent AF) was associated with 2.85 mL/min per 1.73 m² lower eGFRcreat and with a faster decline of eGFRcreat with age. Prevalent AF was associated with a 1.3-fold increased risk of incident reduced kidney function. Conclusions Kidney function, especially eGFRcys, and AF are bidirectionally associated. There are currently no targeted prevention efforts for AF in patients with mild chronic kidney disease and vice versa. Our results could provide the first step to improve prediction/prevention of both conditions.

Kidney function and the risk of sudden cardiac death in the general population

Background

Chronic kidney disease increases sudden cardiac death (SCD) risk, but the association between kidney function and SCD in a general population is largely unknown. Therefore, we investigated the association between kidney function and SCD in a general middle-aged and elderly population.

Methods

We included individuals aged ≥45 years from a prospective population-based cohort study. The association between kidney function assessments [estimated glomerular filtration rate based on serum creatinine (eGFRcreat), cystatin C (eGFRcys) or both (eGFRcreat-cys)] and SCD was investigated using Cox proportional-hazards and joint models. Absolute 10-year risks were computed using competing risk analyses. Mediation analyses were performed using a four-way decomposition method.

Results

We included 9687 participants (median follow-up 8.9 years; mean age 65.3 years; 56.7% women; 243 SCD cases). Lower eGFRcys and eGFRcreat-cys were associated with increased SCD risk [hazard ratio (HR) 1.23, 95% confidence interval (CI) 1.12–1.34 and HR 1.17, 95% CI 1.06–1.29, per 10 mL/min/1.73 m² eGFR decrease]. A significant trend (P = 0.001) across eGFRcys categories was found, with an HR of 2.11 (95% CI 1.19–3.74) for eGFRcys <60 compared with eGFRcys >90 mL/min/1.73 m². Comparing eGFRcys of 90 to 60 mL/min/1.73 m², absolute 10-year risk increased from 1.0% to 2.5%. Identified subgroups at increased risk included older participants and participants with atrial fibrillation. The associations were not mediated by coronary heart disease, hypertension or diabetes.

Conclusions

Reduced kidney function is associated with increased SCD risk in the general population, especially with eGFRcys. eGFRcys could be added to prediction models and screening programmes for SCD prevention.

Changes in aging-induced kidney dysfunction in mice based on a metabolomics analysis

Kidney dysfunction is particularly important in systemic organ injuries caused by aging. Metabolomics are utilized in this study to explore the mechanism of kidney dysfunction during aging by the identification of metabolites and the characterization of metabolic pathways. We analyzed the serum biochemistry and kidney histopathology of male Kunming mice aged 3 months and 24 months and found that the aged mice had inflammatory lesions, aggravated fibrosis, and functional impairment. A high-resolution untargeted metabolomics analysis revealed that the endogenous metabolites in the kidneys and urine of the mice were significantly changed by 25 and 20 metabolites, respectively. A pathway analysis of these differential metabolites revealed six key signaling pathways, namely, D-glutamine and D-glutamate metabolism, purine metabolism, the citrate cycle [tricarboxylic acid (TCA) cycle], histidine metabolism, pyruvate metabolism, and glyoxylate and dicarboxylate metabolism. These pathways are involved in amino acid metabolism, carbohydrate metabolism, and nucleotide metabolism, and these can lead to immune regulation, inflammatory responses, oxidative stress damage, cellular dysfunction, and bioenergy disorders, and they are closely associated with aging and kidney insufficiency. We also screened nine types of sensitive metabolites in the urine as potential biomarkers of kidney dysfunction during the aging process to confirm their therapeutic targets in senior-induced kidney dysfunction and to improve the level of risk assessment for senile kidney injury.