Estimated glomerular filtration rate in clinical practice: Consensus positioning of the Brazilian Society of Nephrology (SBN) and Brazilian Society of Clinical Pathology and Laboratory Medicine (SBPC/ML) / Estimativa da taxa de filtração glomerular na prática clínica: posicionamento consensual da Sociedade Brasileira de Nefrologia (SBN) e Sociedade Brasileira de Patologia Clínica e Medicina Laboratorial (SBPC/ML)

ABSTRACT Chronic kidney disease (CKD) represents one of today's main public health problems. Serum creatinine measurement and estimation of the glomerular filtration rate (GFR) are the main tools for evaluating renal function. There are several equations to estimate GFR, and CKD-EPI equation (Chronic Kidney Disease - Epidemiology) is the most recommended one. There are still some controversies regarding serum creatinine measurement and GFR estimation, since several factors can interfere in this process. An important recent change was the removal of the correction for race from the equations for estimating GFR, which overestimated kidney function, and consequently delayed the implementation of treatments such as dialysis and kidney transplantation. In this consensus document from the Brazilian Societies of Nephrology and Clinical Pathology and Laboratory Medicine, the main concepts related to the assessment of renal function are reviewed, as well as possible existing controversies and recommendations for estimating GFR in clinical practice.

RESUMO A doença renal crônica (DRC) representa um dos principais problemas de saúde pública da atualidade. A dosagem da creatinina sérica e a estimativa da taxa de filtração glomerular (TFG) são as principais ferramentas para avaliação da função renal. Para a estimativa da TFG, existem diversas equações, sendo a mais recomendada a CKD-EPI (Chronic Kidney Disease - Epidemiology). Existem ainda algumas controvérsias com relação à dosagem da creatinina sérica e da estimativa da TFG, uma vez que vários fatores podem interferir nesse processo. Uma importante mudança recente foi a retirada da correção por raça das equações para estimativa da TFG, que superestimavam a função renal, e consequentemente retardavam a implementação de tratamentos como diálise e transplante renal. Neste documento de consenso da Sociedade Brasileira de Nefrologia e Sociedade Brasileira de Patologia Clínica e Medicina Laboratorial são revisados os principais conceitos relacionados à avaliação da função renal, possíveis controvérsias existentes e recomendações para a estimativa da TFG na prática clínica.

Association between Polycystic Ovarian Syndrome, Impaired Kidney Function and Hyperuricaemia: A Systematic Review and Meta-analysis.

Background: Polycystic ovarian syndrome (PCOS) is a gynaecological problem affecting women within reproductive age, accompanied by several metabolic anomalies, thus leading to alteration in kidney function and hyperuricaemia. Due to the high prevalence of cardiometabolic factors in PCOS, there is a need to anticipate an increased number of kidney impairments amongst these women. Objectives: This review aims to investigate the potential link between PCOS, impaired kidney function, and elevated uric acid levels. By elucidating this association, we hope to provide clinicians with a tool to stratify the risk of kidney disease in women diagnosed with PCOS, based on readily available kidney function parameters. Materials and Methods: The recommendations used for the analysis were outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Subsequently, eligible studies were identified using several databases (MEDLINE, ProQuest and EBSCOhost) between 1996 and 2022, with a total of 13 studies included. Serum uric acid, serum creatinine, as well as estimated glomerular filtration rate (eGFR) were evaluated as the outcome of interest. Quality assessment for cohort, case-control and cross-sectional studies was conducted utilising the Newcastle-Ottawa Scale, while Review Manager 5.4 was utilised for meta-analysis. Results: Uric acid was significantly higher in women with PCOS (mean difference [MD] = 0.70, 95% confidence interval [CI] [0.45-0.95], P < 0.00001). Meanwhile, serum creatinine and eGFR were statistically similar in each group (MD = 0.08, 95% CI [-0.05-0.21], P = 0.22 and MD = 3.54, 95% CI [-4.53-11.61], P = 0.39, respectively). Interpretation: This review showed that PCOS was significantly associated with elevated uric acid. However, no significant difference was found between eGFR and creatinine levels compared to healthy controls. Routine uric acid assessment in PCOS patients is recommended as a simple tool for risk stratification. Limitations: No body mass index (BMI) subgroup analysis was done due to limited BMI reporting in our included studies. Quantitative analysis of all kidney function parameters was also limited by sparse data on urea and albumin. PROSPERO Registration Number: CRD42023410092 (02 April 2023).

Association Between Low Kidney Function and Excess Weight Concerning Unfavourable Periodontal Health among Community-dwelling Older Japanese Women.

PURPOSE: To investigate the association of low renal function and overweight with poor periodontal condition in community-dwelling older Japanese women. MATERIALS AND METHODS: In total, 359 older women (age range: 55-74 years) participated in this study. Two periodontal parameters - the number of teeth with a probing pocket depth (PPD) or clinical attachment level (CAL) ≥ 4 mm - were used as the dependent variables. The principal independent variables were low renal function as defined by the estimated glomerular filtration rate (eGFR) and overweight as defined by the body mass index. Poisson regression analysis was used to calculate the ratio of means (RM). RESULTS: The RMs of the number of teeth with a PPD or CAL ≥ 4 mm in an adjusted model without an interaction term were 1.21- or 1.27-fold higher among those with an eGFR < 60, while those among the participants with an eGFR < 60 in the adjusted model with interaction terms for the number of teeth with a PPD or CAL ≥ 4 mm were 1.43- or 1.36-fold higher. In addition, increments of periodontal risk with low renal function and overweight showed a slightly smaller to negative trend. CONCLUSION: The present findings suggest a connection between unfavourable periodontal health and both renal function and being overweight among older Japanese women. A weak negative interaction was also found between poor renal condition and overweight in relation to periodontal condition.

Kidney outcomes with SGLT2is for type 2 diabetes patients: does background treatment with metformin or RASis matter?

Introduction: There is a lack of real-world evidence regarding the impact of concomitant metformin and renin-angiotensin system inhibitors (RASis) on sodium-glucose cotransporter-2 inhibitor (SGLT2i)-associated kidney outcomes. This study was aimed to investigate whether SGLT2i-associated kidney outcomes were modified by the concomitant use of metformin or RASis in patients with type 2 diabetes. Methods: SGLT2i users were identified from three electronic health record databases during May 2016 and December 2017 and categorized into those with and without concomitant use of metformin or RASis. Propensity score matching was performed to minimize baseline differences between groups. Study outcomes were mean estimated glomerular filtration rate (eGFR) change and time to 30%, 40%, and 50% eGFR reductions. A meta-analysis was performed to combine the estimates across databases. Results: After matching, there were 6,625 and 3,260 SGLT2i users with and without metformin, and 6,654 and 2,746 SGLT2i users with and without RASis, respectively. The eGFR dip was similar in SGLT2i users with and without metformin therapy, but was greater in SGLT2i users with RASis compared to those without RASis. Neither metformin nor RASi use had a significant effect on SGLT2i-associated eGFR reductions, as evidenced by the hazard ratios (95% CIs) of 30% eGFR reductions for SGLT2is with versus without metformin/RASis, namely 1.02 (0.87-1.20)/1.09 (0.92-1.31). Such findings were also observed in the outcomes of 40% and 50% eGFR reductions. Conclusion: Using metformin or RASis did not modify SGLT2i-associated kidney outcomes in type 2 diabetes.

The effect of preeclampsia on long-term kidney function among pregnant women with chronic kidney disease.

BACKGROUND AND HYPOTHESIS: The association between superimposed preeclampsia and an elevated risk of long-term kidney function decline or end-stage kidney disease (ESKD) in patients with chronic kidney disease (CKD) has not been determined. This study aimed to analyze the association between preeclampsia and kidney function deterioration in CKD patients. METHODS: This was a retrospective cohort study that included the clinical information of 103 pregnant CKD patients with preeclampsia and 103 matched CKD patients without preeclampsia who were followed-up for a minimum of 1 year after their first pregnancy from January 1, 2009, to May 31, 2022. Robust Cox regression analysis was also conducted to evaluate the effects of preeclampsia on long-term kidney function decline or ESKD in CKD patients. K-M curves were used to compare renal survival within different subgroups via the log-rank test. RESULTS: During the follow-up period, 44 (42.72%) CKD patients with preeclampsia and 20 (19.42%) without preeclampsia had an estimated glomerular filtration rate (eGFR) decrease >30% or developed ESKD. Compared with CKD patients without preeclampsia, the eGFR decreased more significantly in patients with preeclampsia [98.43 (79.48, 116.47) to 81.32 (41.20, 102.97) mL/min/1.73 m2 vs. 99.43 (79.00, 118.50) to 89.44 (63.69, 105.30) mL/min/1.73 m2; P=0.034]. The rate of eGFR decrease was more pronounced in patients with preeclampsia (17.38% vs. 10.05%, p<0.05). Multivariate analysis revealed that early-onset preeclampsia (preeclampsia that developed before 34 weeks of gestation) (HR=2.61, 95% CI=1.32-5.16, P=0.006) and late-onset preeclampsia (HR=2.54, 95% CI=1.34-4.83, P=0.004) were both risk factors for an eGFR decrease >30% or ESKD. CONCLUSION: Preeclampsia was associated with a greater risk of long-term kidney function decline or ESKD among CKD patients, especially in patients with early-onset preeclampsia.

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.

The impact of obesity on body surface area adjusted estimated glomerular filtration rate in patients with chronic kidney disease.

BACKGROUND: Assessment of kidney function is necessary for prescribing renally excreted drugs. The estimated glomerular filtration rate (eGFR) routinely reported by laboratories is indexed to a body surface area (BSA) of 1.73 m2. In obese patients, the indexed eGFR may underestimate directly measured GFR. AIMS: To determine the prevalence of obesity in patients with chronic kidney disease (CKD) and examine the effect of adjusting the indexed eGFR for patient BSA (deindexing) across CKD Stages 2-5. METHODS: We conducted a cross-sectional study of 575 adults with stable CKD from two general nephrology clinics over 6 months. Dialysis and kidney transplant patients were excluded. We used four equations (Mosteller, Dubois, Haycock and Schlich) to determine BSA based on actual body weight and applied Bland-Altman plots and piecewise linear regression to examine the relationship between deindexed and indexed eGFR. RESULTS: The median age was 68 years (58% male). The prevalence of overweight and obesity was 31% and 47% respectively. Mean body mass index was 29.7 kg/m2. The Schlich equation for BSA produced the smallest adjustment in eGFR, while the Haycock equation produced the largest adjustment. Males experienced the largest change in eGFR from deindexing because of larger BSAs. Although bias became increasingly positive with higher eGFR, the linear regression stratified by CKD stage indicated that deindexing had little impact with eGFR <45 mL/min/1.73 m2. CONCLUSIONS: In CKD, deindexing the Chronic Kidney Disease Epidemiology Collaboration eGFR may not be necessary when the eGFR is <45 mL/min/1.73 m2, particularly if the patient is female.

Effect of SGLT2 inhibitors on kidney function of type 2 diabetes patients during Ramadan: A systematic review.

Background: SGLT2 inhibitors are known for their osmotic diuretic effect, and their use by Muslim patients with type 2 diabetes during the fasting month of Ramadan may pose an increased risk of volume depletion, potentially impacting renal function. Methods: We conducted a systematic review registered on PROSPERO (registration number CRD42020204582) of studies published between 2013 and January 2023, sourced from PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials. The study selection criteria included controlled studies that reported the use of SGLT2 inhibitors (SGLT2i) by fasting adult type 2 diabetes patients and provided data on creatinine or estimated glomerular filtration rate (eGFR) as outcomes. Results: Two prospective observational studies, encompassing a total of 359 participants, of which 197 utilized SGLT2 inhibitors, were identified. Our findings indicated that the use of SGLT2 inhibitors during Ramadan did not result in a significant alteration in eGFR. In one study by Hassanein et al., the mean changes in eGFR for the SGLT2i group, as compared to the non-SGLT2i group, were -1.2 ± 19.4 and 3.1 ± 14.8, respectively (p = 0.06). In a study by Shao et al., the least squares mean changes for eGFR in the SGLT2i group, compared to the non-SGLT2i group, were -6.0 ± 1.5 (95% CI, -8.9 to -3.1) and -4.2 ± 1.6 (95% CI, -7.3 to -1.1), respectively (p = 0.39). Conclusion: Despite the limited number of observational studies available, our analysis suggests that the use of SGLT2 inhibitors by type 2 diabetes patients during Ramadan does not appear to significantly impact kidney function.

Blood pressure increases are associated with weight gain and not antiretroviral regimen or kidney function: a secondary analysis from the ADVANCE trial in South Africa.

INTRODUCTION: Recent evidence has raised questions about whether newer HIV treatment regimens, including dolutegravir (DTG) and tenofovir alafenamide (TAF), are associated with increases in blood pressure (BP). METHODS: We assessed changes in BP by treatment regimen and evaluated the relative contribution of kidney function and weight gain to these changes among participants in the ADVANCE phase-3 trial clinical trial in South Africa (study dates: January 2017-February 2022). Our primary outcome of interest was a change in systolic BP (SBP) at 96 and 192 weeks, among those not receiving antihypertensive medication. The secondary outcome was treatment-emergent hypertension at these same time points, defined as BP ≥140/90 mmHg on two occasions, or initiation of antihypertensive medication after week 4 among individuals without hypertension at enrolment. We used linear regression to evaluate the relationship between change in estimated glomerular filtration rate (eGFR) and change in SBP; and Poisson regression to evaluate the relationship between change in eGFR and treatment-emergent hypertension at each time point. All models were adjusted for age, sex, treatment group and change in body mass index (BMI). RESULTS: Over 96 weeks, the average changes in SBP were 1.7 mmHg (95% CI: 0.0-3.4), -0.5 mmHg (95% CI: -2.2 to 1.7) and -2.1 mmHg (95% CI: -3.8 to 0.4) in the TAF/emtricitabine (FTC)/DTG, tenofovir disoproxil fumarate (TDF)/FTC/DTG and TDF/FTC/efavirenz (EFV) groups, respectively. This difference was significant for the TAF/FTC/DTG compared to the TDF/FTC/EFV group (p = 0.002). Over 96 weeks, 18.2% (95% CI: 13.4-22.9), 15.4% (95% CI: 11.0-19.9) and 13.3% (95% CI: 8.9-17.6) of participants developed treatment-emergent hypertension, respectively. In adjusted models, there was no significant relationship between change in eGFR and either outcome. Change in BMI was significantly associated with an increase in SBP, while age was associated with an increased risk of treatment-emergent hypertension. Adjustment for BMI also mitigated the unadjusted relationship between HIV treatment regimen and SBP where present. CONCLUSIONS: In the ADVANCE cohort, weight gain and age accounted for increases in BP and risk of treatment-emergent hypertension. HIV treatment programmes may need to integrate the management of obesity and hypertension into routine care. CLINICAL TRIAL NUMBER: NCT03122262.

Comparison of Glomerular Filtration Rate Equations in a Rural New Mexico Cohort: Results from the COMPASS Study.

Rationale and Objective: The NKF-ASN Task Force recommends accurate kidney function estimation avoiding biases through racial adjustments. We explored the use of multiple kidney function biomarkers and hence estimated glomerular filtration rate (eGFR) equations to improve kidney function calculations in an ethnically diverse patient population. Study design: Prospective community cohort study. Setting and Participants: rural New Mexico clinic with patients > 18 yo. Methods: Markers of kidney function, IDMS-Creatinine (SCr), chemiluminescence Beta-2 Microglobulin (B2M), Nephelometry-calibrated ELISA Cystatin C (CysC), inflammation, glucose tolerance, demographics, BUN/UACR from the baseline visit of the COMPASS cohort, were analyzed by Kernel-based Virtual Machine learning methods. Results: Among 205 participants, the mean age was 50.1, 62% were female, 54.1% Hispanic American and 30.2% Native American. Average kidney function biomarkers were: SCr 0.9 mg/dl, B2M 1.8 mg/L, and CysC 0.7 mg/dl. The highest agreement was observed between SCr and B2M-based eGFR equations [mean difference in eGFRs: (4.48 ml/min/1.73m2], and the lowest agreement between B2M and CysC-based eGFR equations (-24.75 ml/min/1.73m2). There was no pattern of association between the differences in eGFR measures and gender. In the continuous analyses, the absolute eGFR value (p<2 x 10-16) and serum albumin (p =6.4 x 10-5) predicted the difference between B2M- and SCr-based e-GFR. The absolute eGFR value (p<2 x 10-16) and age (p =7.6 x 10-5) predicted the difference between CysC- and SCr-based e-GFR. Limitations: Relatively small sample size, elevated inflammatory state in majority of study participants and no inulin excretion rate measurements. Conclusion: B2M should be strongly considered as a kidney function biomarker fulfilling the criteria for the NKF-ASN. B2M's eGFR equation does not need adjustment for gender or race and showed the highest agreement with SCr-based eGFR equations.

Clinically Evident Cardiopulmonary Congestion Does Not Significantly Impact the Prognosis of Patients With Septic Acute Kidney Injury.

Background: Acute kidney injury (AKI) is a common issue among in-hospital patients, with high mortality rates. Sepsis is a primary cause of AKI, particularly in the intensive care unit. Patients with septic AKI often experience cardiovascular congestion, leading to the formal classification of cardiorenal syndrome type 5. The study aimed to evaluate the prognosis of septic AKI patients with and without clinical evidence of cardiovascular congestion. Methods: This was a retrospective observational study. AKI patients were identified using the in-hospital AKI alert system. Sepsis was diagnosed based on laboratory, clinical, and hemodynamic characteristics, with additional consideration of the quickSOFA score. Cardiovascular congestion was diagnosed by assessing clinical (edema), radiographic (pulmonary congestion), echocardiographic (e.g., wall motion abnormalities), and laboratory variables (e.g., N-terminal pro-B-type natriuretic peptide). Endpoints included in-hospital survival, the need for kidney replacement therapy (KRT), and recovery of kidney function (ROKF). Results: In total, 102 patients were included, and cardiopulmonary congestion was diagnosed in 78.4%. Individuals with congestion did not differ from patients without congestion in any of the pre-defined endpoints. Conclusions: It is justified not to consider clinically apparent cardiovascular congestion in septic AKI patients as a risk factor for death per se. Rather, especially in the case of sepsis, clinically apparent positive fluid balance does not seem to be a disadvantage in terms of survival, KRT, and ROKF.

Cisplatin eligibility in the neoadjuvant setting of patients with muscle-invasive bladder cancer undergoing radical cystectomy.

BACKGROUND: To examine the agreement of different calculated estimated glomerular filtration rate (eGFR) formulas and measured creatinine clearance (CrCI) at the primary diagnosis of muscle-invasive bladder cancer (MIBC). MATERIALS AND METHODS: We performed a multicenter analysis of patients with MIBC, treated with cisplatin-based neoadjuvant chemotherapy (NAC) and radical cystectomy (RC), or with RC alone, between 2011 and 2021. Baseline eGFR was computed using 4 calculated serum equations including Cockcroft-Gault (CG), MDRD, CKD-EPI 2009, and race-free CKD-EPI 2021. To examine the association between calculated eGFR and measured CrCI, subgroup analyses were performed among patients in whom measured 24-hour urine CrCl was determined. Cisplatin-ineligibility was defined as CrCI and/or eGFR < 60 mL/minute per 1.73 m2. RESULTS: Of 956 patients, 30.0%, 33.3%, 31.9%, and 27.7% were found to be cisplatin-ineligible by the CG, MDRD, CKD-EPI, and race-free CKD-EPI equations (P = .052). The concordance between calculated eGFR formulas was rated substantial (Cohen's kappa (k): 0.66-0.95). Among the subgroup (n = 245) with measured CrCl, 37 (15.1%) patients had a CrCI less than 60 mL/minute. Concordance between measured CrCl and calculated eGFR was poor (ĸ: 0.29-0.40). All calculated eGFR formulas markedly underestimated the measured CrCI. Specifically, 78%-87.5% of patients with a calculated eGFR between 40 and 59 mL/minute exhibited a measured CrCI ≥ 60 mL/minute. CONCLUSIONS: Comparing calculated eGFR formulas, similar percentages of patients with MIBC were deemed cisplatin-ineligible. However, a significant number of patients could be upgraded by being cisplatin-fit based on measured CrCI, particularly when the calculated eGFR was falling within the gray range of 40-59 mL/minute.

Which is the best glomerular filtration marker: Creatinine, cystatin C or both?

BACKGROUND: The glomerular filtration rate (GFR) is estimated by the serum or plasma concentration of creatinine and/or cystatin C using equations that include demographic data. The equations worldwide most widely used are those of the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) consortium and updated in 2021 to remove the Afro-American racial correction factor. In 2021 and then in 2023, the European Kidney Function Consortium also developed equations based on creatinine and cystatin C, usable across the full age spectrum, and constructed by including the Q value (i.e. the median creatinine or cystatin C in healthy men and women, which is customizable for specific populations). METHODS: The aim of this narrative review is to examine the strengths and weaknesses of each biomarker. RESULTS: Both biomarkers have non-GFR determinants, namely muscle mass, protein intake and tubular secretion for creatinine; dysthyroidism and systemic corticosteroids for cystatin C, as well as other more debated determinants (diabetes, obesity, proteinuria, inflammatory syndrome). These non-GFR determinants are the reason why no equation based on a single endogenous biomarker has an accuracy within 30% greater than 90% over the entire age spectrum (in at least one patient in 10, estimated GFR is at least 30% higher or at least 30% lower than the measured GFR). CONCLUSION: Equations combining the two biomarkers provide a better estimate of GFR, particularly in the subgroup of patients whose estimates based on each of the biomarkers are highly discordant. These patients must also be identified as being at increased risk of morbidity, particularly cardiovascular, and mortality.

Preexisting Hyperuricemia Before High-Altitude Ascent is Associated with a Slower Recovery of Estimated Glomerular Filtration Rate Following Descent.

Zhao, Linggong, Yujie Huang, and Xiaoling Tan. Preexisting hyperuricemia before high-altitude ascent is associated with a slower recovery of estimated glomerular filtration rate following descent. High Alt Med Biol. 00:00-00, 2024. Objectives: Hypoxia at high altitudes results in elevated uric acid (UA) and reduced estimated glomerular filtration rate (eGFR). However, the impact of a prolonged high-altitude sojourn on UA levels and renal function in patients with preexisting hyperuricemia warrants further exploration. The study was to investigate the eGFR and related factors in patients with preexisting hyperuricemia following exposure to high altitude. Methods: The study included 345 participants, who worked at a high altitude for 1 year. Anthropometric and laboratory indices were collected before ascent (i.e., baseline), as well as 20 and 80 days after descent. The participants were categorized into individuals with hyperuricemia (HUA) or normal uric acid (NUA) group based on the presence or absence of hyperuricemia at baseline. Results: No difference in baseline eGFR was observed between the two groups before ascend or on day 20 after descent (p > 0.05). However, on day 80, eGFR of the HUA group was lower compared with the NUA group (p < 0.05). Correlations existed between post-descent eGFR levels and variables, including sampling time, UA levels, total and direct bilirubin, and baseline grouping. Conclusions: After high-altitude exposure, the recovery of eGFR was delayed in participants with preexisting hyperuricemia. Preexisting hyperuricemia and high-altitude hypoxia jointly contribute to renal impairment.

Population-based reference values for kidney function and kidney function decline in 25- to 95-year-old Germans without and with diabetes.

Understanding normal aging of kidney function is pivotal to help distinguish individuals at particular risk for chronic kidney disease. Glomerular filtration rate (GFR) is typically estimated via serum creatinine (eGFRcrea) or cystatin C (eGFRcys). Since population-based age-group-specific reference values for eGFR and eGFR-decline are scarce, we aimed to provide such reference values from population-based data of a wide age range. In four German population-based cohorts (KORA-3, KORA-4, AugUR, DIACORE), participants underwent medical exams, interview, and blood draw up to five times within up to 25 years. We analyzed eGFRcrea and eGFRcys cross-sectionally and longitudinally (12,000 individuals, age 25-95 years). Cross-sectionally, we found age-group-specific eGFRcrea to decrease approximately linearly across the full age range, for eGFRcys up to the age of 60 years. Within age-groups, there was little difference by sex or diabetes status. Longitudinally, linear mixed models estimated an annual eGFRcrea decline of -0.80 [95% confidence interval -0.82, -0.77], -0.79 [-0.83, -0.76], and -1.20 mL/min/1.73m2 [-1.33, -1.08] for the general population, "healthy" individuals, or individuals with diabetes, respectively. Reference values for eGFR using cross-sectional data were shown as percentile curves for "healthy" individuals and for individuals with diabetes. Reference values for eGFR-decline using longitudinal data were presented as 95% prediction intervals for "healthy" individuals and for individuals with diabetes, obesity, and/or albuminuria. Thus, our results can help clinicians to judge eGFR values in individuals seen in clinical practice according to their age and to understand the expected range of annual eGFR-decline based on their risk profile.

Causal Relationship Between Kidney Function and Cancer Risk: A Mendelian Randomization Study.

RATIONALE & OBJECTIVE: Patients treated with kidney replacement therapy experience a 1.5 to 2-fold increased risk of cancer and cancer mortality compared to the general population. Whether this excess risk extends to people with earlier stages of chronic kidney disease is unclear. This study explored the potentially causal relationship between reduced kidney function and cancer. STUDY DESIGN: Two-sample Mendelian randomization (MR). SETTING & PARTICIPANTS: Genome Wide Association Study (GWAS) summary statistics for estimated glomerular filtration rate (eGFR) (n=567,460) and urinary albuminuria (UACR) (n=127,865) from the CKDGen consortium and cancer outcomes from the UK Biobank (n=407,329). EXPOSURES: eGFR and UACR. OUTCOMES: Overall cancer incidence, cancer-related mortality, and site-specific colorectal, lung, and urinary tract cancer incidence. ANALYTICAL APPROACH: Univariable and multivariable MR were conducted for all outcomes using inverse-variance weighted methods. RESULTS: The mean eGFR and median UACR were 91.4 mL/min/1.73m2 and 9.32 mg/g in the CKDGen and 90.4 mL/min/1.73m2 and 9.29 mg/g in the UK Biobank. There were 98,093 cases of cancer, 6,664 colorectal, 3584 lung, and 3,271 urinary tract. There were 15,850 cases of cancer-related death, The genetic instruments for eGFR and UACR comprised 34 and 38 variants, respectively. Genetically predicted kidney function (eGFR and UACR) was not associated with overall cancer risk or cancer death. No associations of genetically predicted eGFR and UACR with overall cancer incidence were observed; odds ratio (95%CI; p-value) of 0.88 (0.40-1.97; p=0.76) and 0.90 (0.78-1.04; p=0.16), respectively. An adjusted generalized additive model for eGFR and cancer demonstrated evidence of non-linearity. There was no evidence of a causal association between eGFR and cancer in a stratified MR. LIMITATIONS: To avoid overlapping samples a smaller GWAS for UACR was used, reducing the strength of the instrument and potentially introducing population stratification. CONCLUSIONS: These findings did not demonstrate a causal association of kidney function with overall cancer incidence or cancer-related death.

[Functional and oncologic outcomes of partial nephrectomy for cystic renal cell carcinoma: A single-center retrospective study].

OBJECTIVE: To investigate the postoperative renal function and oncologic outcomes of cystic renal cell carcinoma with partial nephrectomy, and to compared the single-center data on surgical outcomes with the Surveillance, Epidemiology, and End Results (SEER) database. METHODS: This was a retrospective study that included the patients with cystic renal cell carcinoma who underwent partial nephrectomy in the Department of Urology, Peking University Third Hospital (PUTH) from 2010 to 2023. The clinical data and depicting baseline characteristics were collected. Renal dynamic imaging and the Chinese Coefficients for Chronic Kidney Disease Epidemiology Collaboration (C-CKD-EPI) formulae were used to calculate the estimated glomerular filtration rate (eGFR). The renal function curves over time were then plotted, and the patients were followed-up to record their survival status. Cases of cystic renal cell carcinoma in the SEER database between 2000 and 2020 were included, propensity score matching (PSM) was performed to balance the differences between SEER cohort and PUTH cohort, and the cancer-specific survival (CSS) curves for both groups were plotted and statistical differences were calculated by the Kaplan-Meier method. RESULTS: A total of 38 and 385 patients were included in the PUTH cohort and SEER cohort, respectively, and 31 and 72 patients were screened in each cohort after PSM. Of the baseline characteristics, only tumor size (P=0.042) was found to differ statistically between the two groups. There was no statistically significant difference between the two cohorts in terms of CSS after PSM (P=0.556). The median follow-up time in the SEER cohort was 112.5 (65, 152) months and a 10-year survival rate of 97.2%, while the PUTH cohort had a median follow-up of 57.0 (20, 1 172) months and a 10-year survival rate of 100.0%. There was no statistically significant difference between eGFR determined by preoperative renal dynamic imaging and the results of the C-CKD-EPI formulae based on creatinine estimation (P=0.073). There was a statistically significant difference in eGFR among the preoperative, short-term postoperative, and long-term postoperative (P < 0.001), which was characterized by the presence of a decline in renal function in the short-term postoperative period and the recovery of renal function in the long-term period. CONCLUSION: Partial nephrectomy for cystic renal cell carcinoma is safe and feasible with favorable renal function and oncologic outcomes.

Impact of glycemic control on residual kidney function and technique failure associated with volume overload in diabetic patients on peritoneal dialysis.

Background: It is unclear whether poor glycemic control contributes to residual kidney function (RKF) decline and consequent volume overload in diabetic patients on peritoneal dialysis (PD). Methods: This retrospective analysis included 80 diabetic patients who started PD at a single center. The first 2 years of patient data were collected to investigate the impact of glycemic control on RKF and volume overload in the early stages of PD. We used the time-averaged glycated hemoglobin (HbA1c) levels to estimate glycemic control. RKF loss was measured as the slope of RKF decline and time to anuria. To assess the association between glycemic control and volume overload, we examined technique failure (TF) associated with volume overload (TFVO), defined as TF due to excessive fluid accumulation. Multivariable linear regression and Cox regression analysis were performed to assess how glycemic control affects RKF and TFVO. Results: Over the first 2 years, the mean rate of RKF decline was -3.25 ± 3.94 mL/min/1.73 m2 per year. Multivariable linear regression showed that higher time-averaged HbA1c was associated with a rapid RKF decline (ß = -0.95; 95% confidence interval [CI], -1.66 to -0.24; p = 0.01). In the adjusted Cox regression analysis, higher time-averaged HbA1c increased the risk of progression to anuria (adjusted hazard ratio [HR], 1.97; 95% CI, 1.29-3.00; p = 0.002) and TFVO (adjusted HR, 2.88; 95% CI, 1.41-5.89; p = 0.004). Conclusion: Poor glycemic control is associated with rapid RKF decline and leads to volume overload in diabetic patients on PD.

Underrepresentation of black individuals in pivotal trials for novel anticancer drugs: Potential consequence of using estimated creatinine clearance to assess kidney function?

BACKGROUND: Black individuals are historically underrepresented in oncology clinical trials. One potential reason for this is the prevalence of kidney disease in Black individuals, utilization of estimated creatinine clearance as a surrogate for glomerular filtration rate (GFR) in oncology, and GFR-based trial eligibility criteria. We characterized the representation of racial minorities in anticancer agent pivotal trials and examined if GFR-based trial eligibility criteria impact the proportion of Black individuals in trial populations. METHODS: We constructed a data repository for anticancer drugs FDA-approved from 2015 to 2019 and associated pivotal trials, from which we extracted trial population racial compositions and GFR-based trial eligibility criteria. We calculated the participation-to-incidence ratio (PIR) and participation-to-mortality ratio (PMR) for a variety of cancer sites, where PIR or PMR >1.2 and <0.8 indicate overrepresentation and underrepresentation, respectively. We evaluated the relationship between GFR eligibility cutoffs and the proportion of Black enrollees with Spearman rank correlation coefficient. RESULTS: We assessed 24,698 patients in 74 trials. Black individuals were underrepresented in all trials (PIR ≤0.48, PMR ≤0.50). For trials with GFR-based eligibility criteria (n = 49), a lower GFR cutoff was modestly associated with a higher proportion of Black enrollees (r = -0.29, p = 0.039). This relationship was strengthened for trials that only used estimated creatinine clearance to estimate GFR (r = -0.43, p = 0.004). CONCLUSIONS: GFR-related eligibility, and specifically the use of estimated creatinine clearance, may contribute to Black individuals being disproportionately excluded from cancer clinical trials. This highlights the need for implementation of contemporary GFR equations and other interventions to boost racial minority trial enrollment.