Different association between renal hyperfiltration and mortality by sex

Predictive effect of estimated glomerular filtrate rate by creatinine or cystatin C on mortality in patients with coronary artery disease

BACKGROUND

Renal dysfunction leads to poor prognosis of patients with coronary artery disease (CAD). Current studies have reported the prognosis or mortality of various diseases using different estimated glomerular filtrate rate (eGFR) formulas, while the performance of these equations is unclear in CAD patients. We aim to evaluate the predict effect of creatinine-based eGFR (eGFRcr), cystatin C-based eGFR (eGFRcys), and both creatinine and cystatin C-based eGFR (eGFRcr-cys) in CAD patients.

METHODS

A total of 23,178 patients with CAD were included from CIN-II cohort study. The association of eGFRcr, eGFRcys and eGFRcr-cys with cardiovascular and all-cause mortality was detected by Cox regression analysis. The predictive effect of eGFRcr, eGFRcys and eGFRcr-cys on mortality was assessed.

RESULTS

During a median follow up of 4.3 years, totally 2051 patients (8.8%) experience all-cause mortality, of which 1427 patients (6.2%) died of cardiovascular disease. For the detection of cardiovascular mortality among CAD patients, eGFRcr-cys had high discriminatory capacity with area under the curve (AUC) in receiver operator characteristic analysis of 0.730, which was significantly better than eGFRcr (AUC = 0.707, p < 0.001) and eGFRcys (AUC = 0.719, p < 0.001). Similar results were observed in all-cause mortality. Restricted cubic spline showed a U-shaped association between eGFRcr and all outcomes in patients with both reduced and supranormal eGFR levels, while a L-shaped association in eGFRcys and eGFRcr-cys.

CONCLUSIONS

Estimated GFR based on both creatinine and cystatin C has highest predictive effect for cardiovascular and all-cause mortality among CAD patients. Meanwhile, supranormal eGFRcr may indicate a higher risk of mortality.

The association between renal hyperfiltration and mortality is not mediated by diabetes mellitus

BACKGROUND

Renal hyperfiltration (RHF), recently established as a risk factor for mortality, is linked to current and subsequent diabetes mellitus (DM). DM could be seen as a mediator in the pathway between RHF and mortality. However, the mediating role of DM in the relationship between RHF and mortality is unclear.

METHODS AND RESULTS

Based on a cohort of 2682 Finnish men from the Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) followed-up for 35 years, we evaluated the association between RHF and mortality, with DM as a mediator, following two methods: a classic mediation analysis approach, using Cox regression, and a counterfactual framework for mediation analysis, using g-computation, Cox regression, and logistic regression. RHF is associated with an increased risk of mortality. This association was not mediated by DM. Under a counterfactual framework and on a hazard ratio scale, RHF association with mortality had a total effect of 1.54 (95% confidence interval, 1.26-1.98) and a controlled direct effect of 1.66 (1.34-2.16).

CONCLUSION

An association between RHF and mortality risk, independent of DM, was established. RHF should be considered, managed, and followed-up as a mortality-associated condition, regardless of the status of DM. We suggest clinicians to consider including RHF screening in routine clinical care, especially diabetic care.

Estimated glomerular filtration rate-dip after medical target therapy associated with increased mortality and cardiovascular events in patients with primary aldosteronism

OBJECTIVES

The correlation of the changes of estimated glomerular filtration rate (eGFR) with long-term cardiovascular complications in patients with primary aldosteronism (PA) following mineralocorticoid receptor antagonists (MRA) treatment remains ambiguous. This prospective study aims to determine factors associated with all-cause mortality and de novo cardiovascular events of PA patients against the eGFR-dip.

METHODS

A total of 208 newly diagnosed PA patients were enrolled from January 2017 to January 2019. MRA was administered with at least a 6-month follow-up. The 'eGFR-dip' was defined as the difference between eGFR at 6 months after MRA treatment and respective baseline eGFR divided by the baseline eGFR.

RESULTS

After a mean 5.7 years follow-up, an eGFR-dip more than 12%, which was detected in 99 (47.6%) of the 208 patients, was a significant independent risk factor predicting composite outcomes (all-cause mortality, de-novo three-point major adverse cardiovascular events, and/or congestive heart failure). Multivariable logistic regression showed that age [odds ratio (OR), 0.94; P = 0.003], pretreatment plasma aldosterone concentration (PAC; OR, 0.98; P  = 0.004), and initial eGFR (OR, 0.97; P  < 0.001) had a positive linkage with the eGFR-dip more than 12%.

CONCLUSIONS

Nearly half of PA patients had an eGFR-dip more than 12% after 6 months of MRA treatment. They had a higher incidence of all-cause mortality and de novo cardiovascular events. Elder age, higher pretreatment PAC, or higher initial eGFR could be associated with an elevated risk of an eGFR-dip more than 12%.

Cardiovascular Risk Related to Glomerular Hyperfiltration in Nondiabetic Individuals: Increasing Visibility is Crucial

Glomerular hyperfiltration (GHF), defined by different estimation formulas, has been widely studied as a predictor of proteinuria and progression to chronic kidney disease (CKD) in diabetic patients. GHF is also an important cardiovascular (CV) risk factor and is related to allcause mortality in non-diabetic populations; however, the upper limit of glomerular filtration rate (GFR) above which it indicates the presence of GHF is weakly defined. This higher risk is as high as in the intermediate stages of CKD and is greater than the presence of diabetes or smoking and is still present in non-albuminuria patients. The original Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) estimation GFR formula showed lower error at higher glomerular filtration (GF) values, was the most used in population studies, and behaved as a better risk predictor. In our review (including approximately 3.6 million individuals), higher GFR values related to increased mortality risk varied from 106.6 to 113.7 ml/min, which are usually not considered risk values for standard guidelines in non-albuminuric patients. However, the lack of consensus on a GF cutoff value, as well as its variability due to sex and progressive reduction with age, affect the knowledge of this serious phenomenon in clinical practice. Although the elderly population is not exempted from the effects of GHF, the search for this phenomenon should be intensified in middle-aged populations because of their lower disease burden, where this situation may be more evident, and the possibility of reversing the consequences is greater. A population group often considered healthy includes obese people, essential hypertensives, smokers, and carriers of fatty liver, where the GHF phenomenon is frequent and is associated with CV disease, kidney disease, and higher mortality. Increasing its visibility by the medical community is essential to reduce the effects of GHF, emphasizing more frequent controls and implementing general measures that include strict control of hypertension, Na restriction, rich in vegetables diets and increased physical activity. Initiatives to confirm the beneficial effects of sodium-glucose cotransporter-2 inhibitors to treat isolated GHF would be an important breakthrough in reducing the severe consequences of this phenomenon.

Urinalysis of individuals with renal hyperfiltration using ATR-FTIR spectroscopy

Abnormal increased glomerular filtration rate (GFR), otherwise known as renal hyperfiltration (RHf), is associated with an increased risk of chronic kidney disease and cardiovascular mortality. Although it is not considered as a disease alone in medicine today, early detection of RHf is essential to reducing risk in a timely manner. However, detecting RHf is a challenge since it does not have a practical biochemical marker that can be followed or quantified. In this study, we tested the ability of ATR-FTIR spectroscopy to distinguish 17 individuals with RHf (hyperfiltraters; RHf (+)), from 20 who have normal GFR (normofiltraters; RHf(-)), using urine samples. Spectra collected from hyperfiltraters were significantly different from the control group at positions 1621, 1390, 1346, 933 and 783/cm. Intensity changes at these positions could be followed directly from the absorbance spectra without the need for pre-processing. They were tentatively attributed to urea, citrate, creatinine, phosphate groups, and uric acid, respectively. Using principal component analysis (PCA), major peaks of the second derivative forms for the classification of two groups were determined. Peaks at 1540, 1492, 1390, 1200, 1000 and 840/cm were significantly different between the two groups. Statistical analysis showed that the spectra of normofiltraters are similar; however, those of hyperfiltraters show diversity at multiple positions that can be observed both from the absorbance spectra and the second derivative profiles. This observation implies that RHf can simultaneously affect the excretion of many substances, and that a spectroscopic analysis of urine can be used as a rapid and non-invasive pre-screening tool.

Pulse pressure and the risk of renal hyperfiltration in young adults: Results from Korea National Health and Nutrition Examination Survey (2010–2019)

Background

High pulse pressure (PP) is associated with increased risk of decline of kidney function. However, little is known about the association between PP and RHF in young adults. This study aimed to evaluate the association between PP and RHF in healthy young adults.

Methods

Data were retrieved from the Korea National Health and Nutrition Examination Survey from 2010 to 2019. A total of 10,365 participants aged 19–39 years with no hypertension and normal kidney function were analyzed. RHF was defined as logarithm transformed estimated glomerular filtration rate (eGFR) with residuals >90th percentile after adjustment for sex, logarithm transformed age, weight, and height. Participants were divided into tertile based on PP levels.

Results

The prevalence of RHF was higher in higher PP tertile group (6.6, 10.5, and 12.7% in T1, T2, and T3; P for trend < 0.001). In multivariable logistic regression analyses, the risk for RHF was increased in higher PP tertiles compared to the lowest tertile [odds ratio (OR), 1.42; 95% confidence interval (CI), 1.19–1.69 in T2; OR, 1.44; 95% CI, 1.20–1.73 in T3]. When PP levels were treated as continuous variable, the risk of RHF was increased 2.36 per 1.0 increase of PP (P < 0.001). In subgroup analyses stratified sex, histories of diabetes or dyslipidemia, and isolated systolic hypertension or isolated diastolic hypertension, there were no significant interactions with PP for the risk for RHF, suggesting that high PP was associated with increased risk of RHF regardless of subgroups. However, the subgroup with BMI showed significant interaction with PP for the risk of RHF, indicating that participants with BMI ≥ 25 kg/m² were at higher risk of RHF with increasing PP levels than those with BMI < 25 kg/m² (OR, 1.89; 95% CI, 1.25–2.87 in BMI < 25 kg/m²; OR, 3.16; 95% CI, 1.74–5.73 in BMI ≥ 25 kg/m²; P for interaction = 0.01).

Conclusion

High PP is associated with an increased risk of RHF in healthy young adults and this association is prominent in obese young adults. The assessment of PP and associated RHF may give benefit to early detect the potential risk of CKD development in young adults.

Metabolic risks in living kidney donors in South Korea

BACKGROUND

Considering the growing prevalence of Western lifestyles and related chronic diseases occurring in South Korea, this study aimed to explore the progression of metabolic risk factors in living kidney donors.

METHODS

This study enrolled living kidney donors from seven hospitals from 1982 to 2016. The controls were individuals that voluntarily received health check-ups from 1995 to 2016 that were matched with donors according to age, sex, diabetes status, baseline estimated glomerular filtration rate, and date of the medical record. Data on hyperuricemia, hypertension, hypercholesterolemia, and overweight/obesity were collected to determine metabolic risks. Logistic regressions with interaction terms between the medical record date and donor status were used to compare the trends in metabolic risks over time in the two groups.

RESULTS

A total of 2,018 living kidney donors and matched non-donors were included. The median age was 44.0 years and 54.0% were women. The living kidney donors showed a lower absolute prevalence for all metabolic risk factors, except for those that were overweight/obese, than the non-donors. The proportion of subjects that were overweight/obese was consistently higher over time in the donor group. The changes over time in the prevalence of each metabolic risk were not significantly different between groups, except for a lower prevalence of metabolic risk factors ≥ 3 in donors.

CONCLUSION

Over time, metabolic risks in living kidney donors are generally the same as in non-donors, except for a lower prevalence of metabolic risk factors ≥3 in donors.

Mortality-based definition of renal hyperfiltration in middle-aged men: a 35-year cohort from Finland

Background

While the impact of low glomerular filtration rate (eGFR) on various outcomes has been extensively studied, the other adverse occurrence, renal hyperfiltration (RHF), remains understudied, poorly defined, and, therefore, its impact on mortality unestablished.

Methods

Using a population-based subcohort from the Kuopio Ischaemic Disease Risk Factor Study restricted to non-diabetic Finnish men aged 54 or 55 years, we followed up n = 1179 study participants for up to 35 years. We evaluated the hazard of all-cause mortality associated to RHF at different cutoff points defining eGFR. Based on models’ accuracy we suggested an optimal eGFR cutoff point for the definition of RHF. We divided the RHF category to three subgroups and evaluated them in terms of baseline characteristics and mortality hazard.

Results

The eGFR value of 97 mL/min/1.73 m² corresponded to the models with the highest accuracy. Overall RHF associated with an increased risk of mortality (hazard ratio [HR] 1.42; 95% confidence interval [CI] 1.21 to 1.67). Moderate RHF associated with a decreased HR of mortality when compared to mild (0.64; 95% CI 0.46 to 0.9) or to extreme RHF (0.61; 95% CI 0.43 to 0.85), suggesting a rather U-shaped relationship between RHF’s eGFR values and mortality hazard.

Conclusion

The burden of increased eGFR within what is still considered normal eGFR category was highly underestimated. RHF’s eGFR values had a U-shaped association with the risk of overall mortality. A more uniform consensual definition of RHF is needed, as higher to normal eGFR values that are not without consequences.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11255-021-03048-6.

The minimum-mortality estimated glomerular filtration rate percentile shifts upward in the aged population: a nationwide population-based study

Background

The estimated glomerular filtration rate (eGFR) is a biomarker not only for kidney function, but also for major clinical outcomes. We aimed to evaluate the patterns of mortality across the entire eGFR percentile spectrum using a population-based dataset.

Methods

We retrospectively reviewed the National Health Insurance Service (NHIS) database for people who received nationwide health check-ups from 2009 to 2012. Subjects who were ≥45 years old and had one or more serum creatinine values available were included in the study. The primary outcome was all-cause mortality as a function of eGFR percentile.

Results

The middle-aged group (45–64 years) showed a U-shaped pattern of association between eGFR percentile and all-cause mortality. The minimum-mortality eGFR percentile was shifted upward in the elderly group (≥65 years). Specifically, the minimum-mortality eGFR percentiles were the 28th percentile (83.8 mL/min/1.73 m²) for middle-aged males, the 63rd percentile (86.2 mL/min/1.73 m²) for elderly males, the 42nd percentile (102.8 mL/min/1.73 m²) for middle-aged females and the 75th percentile (90.1 mL/min/1.73 m²) for elderly females. Diabetes and hypertension shifted the minimum-mortality eGFR percentile upward in the middle-aged group. This pattern was attenuated in the elderly group.

Conclusions

The eGFR percentile showing minimum mortality moves upward in the aged population as well as patients with diabetes and hypertension, which might reduce the clinical significance of hyperfiltration. Risk stratification for mortality should be approached differently according to the specific conditions of the patient group.

Renal hyperfiltration is independently associated with increased all-cause mortality in individuals with type 2 diabetes: a prospective cohort study

INTRODUCTION

In addition to favoring renal disease progression, renal 'hyperfiltration' has been associated with an increased risk of death, though it is unclear whether and how excess mortality is related to increased renal function. We investigated whether renal hyperfiltration is an independent predictor of death in patients with type 2 diabetes from the Renal Insufficiency And Cardiovascular Events Italian multicenter study.

RESEARCH DESIGN AND METHODS

This observational, prospective cohort study enrolled 15 773 patients with type 2 diabetes consecutively attending 19 Italian diabetes clinics in 2006-2008. Serum creatinine, albuminuria, cardiovascular risk factors, and complications/comorbidities were assessed at baseline. Vital status on 31 October 2015 was retrieved for 15 656 patients (99.26%). Patients were stratified (A) by absolute estimated glomerular filtration rate (eGFR) values in eGFR deciles or Kidney Disease: Improving Global Outcomes (KDIGO) categories and (B) based on age-corrected thresholds or age and gender-specific 95th and 5th percentiles in hyperfiltration, hypofiltration, and normofiltration groups.

RESULTS

The highest eGFR decile/category and the hyperfiltration group included (partly) different individuals with similar clinical features. Age and gender-adjusted death rates were significantly higher in deciles 1, 9, and 10 (≥103.9, 50.9-62.7, and <50.9 mL/min/1.73 m², respectively) versus the reference decile 3 (92.9-97.5 mL/min/1.73 m²). Mortality risk, adjusted for multiple confounders, was also increased in deciles 1 (HR 1.461 (95% CI 1.175 to 1.818), p=0.001), 9 (1.312 (95% CI 1.107 to 1.555), p=0.002), and 10 (1.976 (95% CI 1.673 to 2.333), p<0.0001) versus decile 3. Similar results were obtained by stratifying patients by KDIGO categories. Death rates and adjusted mortality risks were significantly higher in hyperfiltering and particularly hypofiltering versus normofiltering individuals.

CONCLUSIONS

In type 2 diabetes, both high-normal eGFR and hyperfiltration are associated with an increased risk of death from any cause, independent of confounders that may directly impact on mortality and/or affect GFR estimation. Further studies are required to clarify the nature of this relationship.

TRIAL REGISTRATION NUMBER

NCT00715481.

Association of Glomerular Hyperfiltration and Cardiovascular Risk in Middle-Aged Healthy Individuals

IMPORTANCE

Glomerular hyperfiltration is associated with increased risk of cardiovascular disease in high-risk conditions, but its significance in low-risk individuals is uncertain.

OBJECTIVE

To determine whether glomerular hyperfiltration is associated with increased cardiovascular risk in healthy individuals.

DESIGN, SETTING, AND PARTICIPANTS

This was a prospective population-based cohort study, for which enrollment took place from August 2009 to October 2010, with follow-up available through March 31, 2016. Analysis of the data took place in October 2019. The cohort was composed of 9515 healthy individuals, defined as individuals without hypertension, diabetes, cardiovascular disease, estimated glomerular filtration rate (eGFR) less than 60 mL/min/1.73 m2, or statin and/or aspirin use, identified among 20 004 patients aged 40 to 69 years with health information accessed through the CARTaGENE research platform.

EXPOSURES

Individuals with glomerular hyperfiltration (eGFR >95th percentile after stratification for sex and age) were compared with individuals with normal filtration rate (eGFR 25th-75th percentiles).

MAIN OUTCOMES AND MEASURES

Adverse cardiovascular events were defined as a composite of cardiovascular mortality, myocardial infarction, unstable angina, heart failure, stroke, and transient ischemic attack. Risk of adverse cardiovascular events was assessed using Cox and fractional polynomial regressions and propensity score matching.

RESULTS

From the 20 004 CARTaGENE participants, 9515 healthy participants (4050 [42.6%] male; median [interquartile range] age, 50.4 [45.9-55.6] years) were identified. Among these, 473 had glomerular hyperfiltration (median [interquartile range] eGFR, 112 [107-115] mL/min/1.73 m2) and 4761 had a normal filtration rate (median [interquartile range] eGFR, 92 [87-97] mL/min/1.73 m2). Compared with the normal filtration rate, glomerular hyperfiltration was associated with an increased cardiovascular risk (hazard ratio, 1.88; 95% CI, 1.30-2.74; P = .001). Findings were similar with propensity score matching. The fractional polynomial regression showed that only the highest eGFR percentiles were associated with increased cardiovascular risk. The cardiovascular risk of individuals with glomerular hyperfiltration was similar to that of the 597 participants with an eGFR between 45 and 60 mL/min/1.73 m2 (hazard ratio, 0.90; 95% CI, 0.56-1.42; P = .64).

CONCLUSIONS AND RELEVANCE

These findings suggest that glomerular hyperfiltration is independently associated with increased cardiovascular risk in middle-aged healthy individuals. This risk profile appears to be similar to stage 3a chronic kidney disease.

Long-term Mortality Risks Among Living Kidney Donors in Korea

RATIONALE & OBJECTIVE

Living kidney donors may have a higher risk for death and kidney failure. This study aimed to investigate the long-term mortality experience of living kidney donors compared with members of the general public in Korea who underwent voluntary health examinations.

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

We first calculated standardized mortality ratios for 1,292 Korean living kidney donors who underwent donor nephrectomy between 1982 and 2016 and 72,286 individuals who underwent voluntary health examinations between 1995 and 2016. Next we compared survival between the 1,292 living kidney donors and a subgroup of the health examination population (n=33,805) who had no evident contraindications to living kidney donation at the time of their examinations. Last, a matched comparator group was created from the health examination population without apparent contraindication to donation by matching 4,387 of them to donors (n=1,237) on age, sex, body mass index, estimated glomerular filtration rate, urine dipstick albumin excretion, previously diagnosed hypertension and diabetes, and era.

EXPOSURES

Donor nephrectomy.

OUTCOMES

All-cause mortality and other clinical outcomes after kidney donation.

ANALYTICAL APPROACH

First, standardized mortality ratios were calculated separately for living kidney donors and the health examination population standardized to the general population. Second, we used Cox regression analysis to compare mortality between living kidney donors versus the subgroup of the health examination population without evident donation contraindications. Third, we used Cox regression analysis to compare mortality between living kidney donors and matched comparators from the health examination population without apparent contraindication to donation.

RESULTS

The living kidney donors and health examination population had excellent survival rates compared with the general population. 52 (4.0%) of 1,292 kidney donors died during a mean follow-up of 12.3±8.1 years and 1,072 (3.2%) of 33,805 in the health examiner subgroup without donation contraindications died during a mean follow-up of 11.4±6.1 years. Donor nephrectomy did not elevate the hazard for mortality after multivariable adjustment in kidney donors and the 33,805 comparators (adjusted HR, 1.01; 95% CI, 0.71-1.44; P=0.9). Moreover, living donors showed a similar mortality rate compared with the group of matched healthy comparators.

LIMITATIONS

Donors from a single transplantation center. Residual confounding owing to the observational study design.

CONCLUSIONS

Kidney donors experienced long-term rates of death comparable to nondonor comparators with similar health status.

Renal hyperfiltration defined by high estimated glomerular filtration rate: A risk factor for cardiovascular disease and mortality

Renal hyperfiltration, defined as an increased glomerular filtration rate above normal values, is associated with early phases of kidney disease in the setting of various conditions such as obesity and diabetes. Although it is recognized that glomerular hyperfiltration, that is, increased filtration per nephron unit (usually studied at low glomerular filtration levels and often referred to as single nephron hyperfiltration), is a risk factor for the progression of chronic kidney disease, the implications of having renal hyperfiltration for cardiovascular disease and mortality risk are incompletely understood. Recent evidence from diverse populations, including healthy individuals and patients with diabetes or established cardiovascular disease, suggests that renal hyperfiltration is associated with a higher risk of cardiovascular disease and all-cause mortality. In this review, we critically summarize the existing studies, discuss possible mechanisms, and describe the remaining gaps in our knowledge regarding the association of renal hyperfiltration with cardiovascular disease and mortality risk.

Impaired fasting glucose is associated with lower glomerular filtration rate decline among men but not women -a large cohort study from Israel

OBJECTIVES

Early stages of diabetes are associated with an increased glomerular filtration rate (GFR). Little is known, however, about the change in GFR among patients with impaired fasting glucose (IFG). We aimed to evaluate the yearly decline rate of GFR among IFG patients.

METHODS

A retrospective analysis of a large cohort of subjects attending a medical screening center in Israel. Patients with diabetes mellitus and patients with decreased estimated GFR (eGFR) were excluded. We divided the cohort into 2 subgroups; Healthy controls and impaired fasting control subjects. For each group, we calculated the average yearly estimated GFR decline (ΔeGFR). The results were adjusted for age, BMI, hypertension and smoking status.

RESULTS

8176 subjects met the inclusion criteria. The median follow up time was 4.8 years (range 2.0 to 13.4). For the whole cohort (men and women), yearly ΔeGFR was -0.68 among healthy controls, and - 0.47 among IFG patients (p = .003). Among men, average yearly ΔeGFR in healthy controls and IFG patients was -0.7 and - 0.4, respectively (p = .0002). All results remained significant after adjusting for age, BMI, hypertension, smoking status and level of HDL and triglycerides. In contrast, among IFG women there was no significant difference in ΔeGFR in comparison with healthy women.

CONCLUSIONS

Impaired fasting glucose is associated with a decreased rate of GFR reduction compared with healthy subjects. This effect is gender dependent - observed in men but not in women. A mechanism of glomerular hyperfiltration might be involved.

Glomerular Hyperfiltration as Predictor of Cardiometabolic Risk Factors among Children and Adolescents: The Childhood and Adolescence Surveillance and Prevention of Adult-V Study

Background

The prevalence of glomerular hyperfiltration and chronic kidney disease is increasing worldwide in parallel with obesity hypertension epidemic. The effect of increases in glomerular filtrations (GFR) in children with metabolic syndrome has not been studied. The purpose of the present study is to investigate the relationship between GFR and cardiometabolic risk factors in a large sample of pediatric population.

Methods

In this nationwide survey, 3800 participants were selected by cluster random sampling from 30 provinces in Iran. Anthropometric measures, biochemical, and clinical parameters were measured. We also measured estimated GFR (eGFR) using the recently modified Schwartz equations and other known cardiometabolic risk factors such as elevated total cholesterol, high low-density lipoprotein cholesterol (LDL-C), and obesity.

Results

The response rate was 91.5% (n = 3843). The mean and standard deviation (SD) (Mean ± SD) of eGFR for girls, boys, and total population were 96.71 ± 19.46, 96.49 ± 21.69, and 96.59 ± 20 ml/min/1.73 m², respectively. Overall, 38.7% of the participants did not have any cardiometabolic risk factor. In multivariate models, the risk of elevated systolic blood pressure (BP) (odds ratio [OR]: 1.48; 95% confidence interval [CI]: 1.08-2.02), elevated diastolic BP (OR: 1.48; 95% CI: 1.08-2.02), elevated LDL-C (OR: 1.35; 95% CI: 1.07-1.70), and obesity (OR: 1.70; 95%CI: 1.24-2.33) were significantly higher in participants with higher eGFR level than those with the lower level but not with low level of high-density lipoprotein cholesterol (OR: 0.72; 95% CI: 0.60-0.88).

Conclusions

This study demonstrates an association between glomerular hyperfiltration and obesity-related hypertension in a large sample of the Iranian pediatric population, independently of other classical risk factors.

Association of co-exposure to heavy metals with renal function in a hypertensive population

BACKGROUND

Chronic kidney disease (CKD) is an increasing health problem worldwide. Recent studies have suggested the potential associations between exposure to metals and CKD events, particularly in participants with hypertension. However, relevant studies are limited.

OBJECTIVES

We aimed to explore the associations of metal exposure with renal function in participants with essential hypertension.

METHODS

Nine hundred and thirty-four participants with essential hypertension were recruited at the Department of Cardiology, Union Hospital, Wuhan, China. We measured the levels of chromium, cadmium, thallium and uranium in urine and calculated the estimated glomerular filtration rate (eGFR) for renal function. Multivariable linear regression models adjusted for potential confounders were applied.

RESULTS

After adjusting for potential confounders and other metals, doubling of urinary chromium or uranium levels decreased eGFR by 2.90 (95% confidence interval, 2.04 to 3.76) and 1.87 (0.58 to 3.15) mL/min per 1.73m², respectively. Co-exposure to chromium and uranium was found to greatly decrease eGFR, particularly in women. Compared with those in the low exposure group, women with high exposure to chromium and uranium had a 11.36 (3.66 to 19.07) mL/min per 1.73m² adjusted decline in eGFR. Higher urinary thallium levels were positively related to elevated eGFR in men. The adjusted increase in eGFR with doubling of thallium levels was 3.12 (1.14 to 5.10) mL/min per 1.73m². Sex-difference in the associations of exposure to heavy metals with eGFR was also suggested.

CONCLUSIONS

Our findings suggest that environmental exposure to chromium and uranium might contribute to a decline in eGFR in individuals with hypertension. The associations of exposure to heavy metals with eGFR might be sex-different. Further studies are warranted to confirm our findings and clarify the underlying mechanisms.

Midterm eGFR and Adverse Pregnancy Outcomes: The Clinical Significance of Gestational Hyperfiltration

BACKGROUND AND OBJECTIVES

Although hemodynamic adaptation plays a crucial role in maintaining gestation, the clinical significance of midterm renal hyperfiltration (MRH) on pregnancy outcomes is unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was an observational cohort study. Women with a singleton pregnancy and a serum creatinine measurement during their second trimester were followed at two university hospitals in Korea between 2001 and 2015. Those with substantial renal function impairment or who delivered during the second trimester were not considered. MRH was represented by the highest eGFR, which was calculated using the Chronic Kidney Disease Epidemiology Collaboration method. An adverse pregnancy event was defined by the composition of preterm birth (gestational age <37 weeks), low birth weight (<2.5 kg), and preeclampsia.

RESULTS

Data from 1931 pregnancies were included. The relationship between midterm eGFR and adverse pregnancy outcomes, which occurred in 538 mothers, was defined by a nonlinear U-shaped curve. The adjusted odds ratio and associated 95% confidence interval (95% CI) of an adverse pregnancy outcome for eGFR levels below and above the reference level of 120-150 ml/min per 1.73 m2 were 1.97 (95% CI, 1.34 to 2.89; P<0.001) for ≥150 ml/min per 1.73 m2; 1.57 (95% CI, 1.23 to 2.00; P<0.001) for 90-120 ml/min per 1.73 m2; and 4.93 (95% CI, 1.97 to 12.31; P<0.001) for 60-90 ml/min per 1.73 m2. Moreover, among mothers without baseline CKD, women with adverse pregnancy outcomes had less prominent MRH than those without (P<0.001).

CONCLUSIONS

We identified a unique U-shaped relationship between midterm eGFR and adverse pregnancy outcomes, and the optimal range of midterm eGFR levels was 120-150 ml/min per 1.73 m2. In those without evident functional renal impairment, the absence of prominent MRH might be a significant risk factor for poor pregnancy outcomes.