Physical exercise, fasting glucose, and renal hyperfiltration in the general population: the Renal Iohexol Clearance Survey in Tromsø 6 (RENIS-T6)

Dose-dependent association between estimated glomerular filtration rate and the subsequent risk of depression: An analysis of a nationwide epidemiological dataset

BACKGROUND

Although the risk of depression is well-known in the patients with kidney dysfunction, especially at the late stages, little is known about the exact point at which the decline in estimated glomerular filtration rate (eGFR) begins to significantly increase the risk of depression. In the present study, we analysed a nationwide epidemiological dataset to investigate the dose-dependent association between baseline eGFR and a future risk of developing depression in a general population.

METHODS

We retrospectively analysed 1,518,885 individuals (male: 46.3%) without a history of depression identified between April 2014 and November 2022 within a nationwide epidemiological database, provided by DeSC Healthcare (Tokyo, Japan). We investigated the association of eGFR with the incidence of depression using Cox regression analyses and also conducted cubic spline analysis to investigate the dose-dependent association between eGFR and depression.

RESULTS

In the mean follow-up of 1218 ± 693 days, 45,878 cases (3.0% for total participants, 2.6% for men and 3.3% for women) of depression were recorded. The risk of depression increased with the eGFR decline as well as the presence of proteinuria. Multivariable Cox regression analysis showed the hazard ratio (95% CI) of depression in each kidney function category (eGFR ≥90, 60-89, 45-59, 30-44, 15-29, and < 15 mL/min/1.73 m2) was 1.14 (1.11-1.17), 1 (reference), 1.11 (1.08-1.14), 1.51 (1.43-1.59), 1.77 (1.57-1.99) and 1.77 (1.26-2.50), respectively. In the cubic spline analysis, the risk of depression continued to increase monotonically as the eGFR declined when the eGFR fell below approximately 65 mL/min/1.73 m2.

CONCLUSIONS

Our analysis using a large-scale epidemiological dataset presented the dose-dependent association between eGFR decline and the risk of depression, which highlights the importance of incorporating mental health assessments into the routine care of patients with kidney dysfunction, regardless of the stage of their disease.

Association of kidney function with physical performance: the Maastricht study

BACKGROUND

Kidney failure has been associated with decreased physical capacity, although evidence regarding the physical performance of individuals with earlier stages of chronic kidney disease (CKD) remains limited.

METHODS

Cross-sectional data were derived from the prospective, population-based Maastricht Study. Multivariate linear regression models were fitted to assess the association of estimated glomerular filtration rate (eGFR) and albuminuria categories with physical performance test outcomes.

RESULTS

Overall, 7396 participants were included. Compared to eGFR 60-90 ml/min/1.73 m2, values < 60 ml/min/1.73 m2 were associated with significantly shorter 6-min walk distance (β: - 13.04 m, 95% confidence intervals-CI - 19.95; - 6.13), worse timed chair rise stand test time (β: 0.91 s, 95% CI 0.36; 1.47), lower maximal grip (β: - 0.83 kg, 95% CI - 1.50; - 0.15) and elbow flexion (β: - 3.64 Nm, 95% CI - 7.11; - 0.16) strength. Additionally, eGFR > 90 ml/min/1.73 m2 was linked to significantly shorter 6-min walk distance (β: - 6.13 m, 95% CI - 9.44; - 2.82). Urinary albumin excretion > 30 mg/24 h was associated with shorter 6-min walk distance (β: - 12.48 m, 95% CI - 18.28; - 6.68), worse timed chair rise stand test time (β: 0.51 s, 95% CI 0.11; 1.06), lower maximal grip (β: - 1.34 kg, 95% CI - 1.91; - 0.76) and elbow flexion strength (β: - 3.31 Nm, 95% CI - 5.80; - 0.82).

CONCLUSIONS

Reduced eGFR and higher albuminuria levels were associated with worse physical performance, especially shorter 6-min walk distance and lower muscle strength. The relationship between eGFR and physical function was non-linear, with also high eGFR values being associated with worse performance, especially in the six-minute walk test.

Longitudinal Analysis of Renal Function Changes in Elderly Populations: Health Status Evaluation and Risk Factor Assessment

Background

This study aims to investigate GFR decline in elderly subjects with varying physical conditions and analyze key risk factors impacting renal function changes.

Methods

We obtained data from patients between 2017 and 2019, and matched healthy elderly subjects based on gender and age. Data collected for all subjects included annual measurements of fast blood glucose (GLU), glycated hemoglobin (HbA1c), low-density lipoprotein cholesterol (LDL-c), blood albumin (ALB), blood uric acid (UA), urine protein (UP), and systolic blood pressure (SBP). Additionally, information on coexisting diseases was gathered. The Full Age Spectrum (FAS) equation was used to calculate eGFR.

Results

A total of 162 patients with complete 3-year renal dynamic imaging were included, including 84 patients in the kidney disease group (K group) and 78 patients in the non-kidney disease group (NK group). Ninety individuals were selected as the healthy group (H group). The annual decline rate in the K group was the fastest, which exceeded 5mL/min/1.73m2 (P < 0.05). Group (K group: β=-40.31, P<0.001; NK group: β=-26.96, P<0.001), ALB (β=-0.38, P=0.038) and HbA1c (β=1.36, P=0.029) had a significant negative impact on the eGFR changes. For participants who had negative proteinuria: K group had the most significant annual eGFR decline.

Conclusion

The presence of kidney disease, along with proteinuria nor not, can lead to a marked acceleration in kidney function decline in elderly. We categorize elderly individuals with an annual eGFR decline of more than 5 mL/min/1.73m2 as the "kidney accelerated aging" population.

The Association between Urinary Sodium-Potassium Ratio, Kidney Function, and Blood Pressure in a Cohort from the General Population

INTRODUCTION

Subclinical kidney dysfunction may contribute to salt-sensitive hypertension. We assessed the association between the urinary sodium-potassium ratio (Na/K ratio) and blood pressure (BP) in a general population cohort without diabetes, chronic kidney disease, cardiovascular disease, or treated hypertension. We investigated whether any such association was mediated by the kidney function markers measured glomerular filtration rate (mGFR), urinary albumin-creatinine ratio (ACR), and urinary epidermal growth factor-creatinine ratio (EGF-Cr).

METHODS

The Tromsø Study is a population-based study of inhabitants of the municipality of Tromsø, Northern Norway. Participants aged 50-62 years, without diabetes, chronic kidney disease, or cardiovascular disease, were invited to the substudy Renal Iohexol Clearance Survey in Tromsø 6 (RENIS-T6; 2007-09). For the present study, we excluded participants reporting the use of 1 or more antihypertensive agents, leaving 1,311 RENIS-T6 participants for a cross-sectional analysis. We measured office BP, 24-h ambulatory blood pressure (ABP), and mGFR using iohexol clearance. Na/K ratio, ACR, and EGF-Cr were measured in morning urine samples.

RESULTS

Urinary Na/K ratio was significantly associated with systolic office BP and ABP independently of cardiovascular risk factors and kidney function markers. A one-standard deviation unit increase in the Na/K ratio was associated with increased systolic ABP by 1.0 (0.3-1.6) mm Hg. Urinary Na/K ratio showed a stronger association with office BP than ABP. EGF-Cr, ACR, and mGFR did not mediate the relationship between urinary Na/K ratio and systolic BP.

CONCLUSIONS

In a representative sample of the middle-aged North-European population without diabetes, chronic kidney disease, cardiovascular disease, or treated hypertension, there was a consistent association between urinary Na/K ratio and BP. The association with BP was not mediated through kidney function measures, suggesting a relationship between a diet with high sodium and low potassium and higher BP regardless of kidney function.

Renal dysfunction in AQP4 NMOSD and MS; a potential predictor of relapse and prognosis

OBJECTIVE

This study aimed to explore the association between kidney function and the risk of relapse as well as prognosis in patients with aquaporin-4 (AQP4)-immunoglobulin G (IgG)-seropositive neuromyelitis optica spectrum disorder (NMOSD).

METHODS

We focused on patients experiencing their first onset of AQP4-IgG-seropositive NMOSD. Data on demographics, disease characteristics, and kidney function were collected, with the primary assessment utilizing the estimated glomerular filtration rate (eGFR). Associations between eGFR and relapse risk were examined using multivariate Cox proportional hazards regression models. Additionally, logistic regression models were employed to evaluate the impact of eGFR on clinical prognosis.

RESULTS

Our analysis revealed glomerular hyperfiltration and impaired urine concentrating ability in patients with AQP4-IgG-seropositive NMOSD. Multivariate Cox proportional hazards regression demonstrated a positive correlation between eGFR and the risk of relapse. Logistic regression analysis further identified higher eGFR as an independent predictor of disease relapse and prognosis in AQP4-IgG-seropositive NMOSD patients.

CONCLUSIONS

The eGFR of patients with AQP4-IgG-seropositive NMOSD emerges as a potential diagnostic biomarker for this condition, indicating its significance in predicting both relapse risk and clinical prognosis.

The Association Between Metabolic Syndrome, Hyperfiltration, and Long-Term GFR Decline in the General Population

Introduction

One-quarter of adults worldwide meet the criteria of metabolic syndrome (MetS). MetS increases the risk of diabetes, chronic kidney disease (CKD), and cardiovascular disease. However, the association between MetS, hyperfiltration, and long-term glomerular filtration rate (GFR) decline in the general population is unknown.

Methods

In the Renal Iohexol Clearance Survey (RENIS), we investigated 1551 people aged 50 to 63 years; representative of the general population without diabetes, cardiovascular disease, or kidney disease. The GFR was measured using iohexol clearance at baseline and twice during 11 years of follow-up. Hyperfiltration at baseline was defined as an absolute GFR (ml/min) above the 90th percentile adjusted for sex, age, and height, because these variables correlate with nephron number. MetS was defined as increased waist circumference and 2 risk factors among hypertension, hyperglycemia, elevated triglycerides, and low high density lipoprotein (HDL)-cholesterol levels. The GFR decline rate was calculated using linear mixed models.

Results

MetS was associated with hyperfiltration at baseline (odds ratio [OR] 2.4; 95% CI: 1.7-3.5, P < 0.001) and a steeper GFR decline rate during follow-up (-0.30 [-0.43 to -0.16] ml/min per 1.73 m2/yr). Compared to those without MetS, GFR decline was -0.83 (95% CI: -1.13 to -0.53) ml/min per 1.73 m2/yr in those with MetS and baseline hyperfiltration and -0.15 (-0.30 to 0.00) in those MetS without hyperfiltration, P = 0.2 for interaction.

Conclusions

In the nondiabetic general population, those with MetS had an increased OR of hyperfiltration and steeper long-term GFR decline. Randomized controlled trials are needed to explore whether treatment of hyperfiltration can prevent loss of GFR in persons with MetS.

Association of glomerular hyperfiltration with carotid artery plaque in the general population

BACKGROUND AND AIMS

Glomerular hyperfiltration (GHF) is a hemodynamic change of the kidney as an adaptive response to nephron loss. Although GHF is associated with metabolic risk factors and cardiovascular disease (CVD), the mechanisms that explain these relationships remain largely unknown. This is partially caused by a non-unified definition of GHF based on pathophysiologic vascular changes. Thus, the objective of this study was to evaluate the association between various definitions of GHF and carotid plaque in a health checkup cohort.

METHODS

A total of 4493 individuals without history of CVD who had carotid ultrasonography (USG) results available between January 2016 and June 2018 were enrolled. GHF was defined as >90th percentile of eGFR residuals after adjusting for confounding factors. Carotid plaque score was calculated based on carotid USG results.

RESULTS

Of 4493 individuals (mean age, 52.3 ± 10.1 years; 3224 [71.8%] males), 449 subjects were included in the GHF group (mean eGFR, 107.0 ± 7.1 ml/min/1.73 m²) and 4044 subjects were included in the non-GHF group (mean eGFR, 92.5 ± 12.3 ml/min/1.73 m²). When the GHF group was compared to the non-GHF group, GHF was associated with the presence of significant carotid plaque (carotid plaque score ≥2) (adjusted OR: 1.46; 95% CI: 1.16 to 1.83; p = 0.001). GHF defined in this study showed higher sensitivity to the presence of carotid plaque than other definitions of GHF.

CONCLUSIONS

GHF status was associated with risk of carotid plaque in individuals without history of CVD. Presence of subclinical carotid plaque was associated with risk of future CVD. Therefore, GHF based on creatinine could be a useful surrogate marker for surveillance of CVD in asymptomatic individuals.

Association of High-Density Lipoprotein Cholesterol With GFR Decline in a General Nondiabetic Population

Introduction

Although lower high-density lipoprotein cholesterol (HDL-C) levels are considered a risk factor for cardiovascular disease (CVD), experimental evidence suggest that aging, inflammation, and oxidative stress may remodel HDL-C, leading to dysfunctional HDL-C. Population studies on HDL-C and loss of the glomerular filtration rate (GFR) reported inconsistent results, but they used inaccurate estimates of the GFR and may have been confounded by comorbidity.

Methods

We investigated the association of HDL-C levels with risk of GFR loss in a general population cohort; the participants were aged 50-62 years and did not have diabetes, CVD, or chronic kidney disease (CKD) at baseline. The GFR was measured using iohexol-clearance at baseline (n=1627) and at the follow-up (n=1324) after a median of 5.6 years. We also investigated any possible effect modification by low-grade inflammation, physical activity, and sex.

Results

Higher HDL-C levels were associated with steeper GFR decline rates and increased risk of rapid GFR decline (>3 ml/min per 1.73 m² per year) in multivariable adjusted linear mixed models and logistic regression (-0.64 ml/min per 1.73 m² per year [95% CI -0.99, -0.29; P < 0.001] and odds ratio 2.7 [95% CI 1.4, 5.2; P < 0.001] per doubling in HDL-C). Effect modifications indicated a stronger association between high HDL-C and GFR loss in physically inactive persons, those with low-grade inflammation, and men.

Conclusion

Higher HDL-C levels were independently associated with accelerated GFR loss in a general middle-aged nondiabetic population.

Energy Expenditure Improved Risk Factors Associated with Renal Function Loss in NAFLD and MetS Patients

To assess the efficacy of three lifestyle interventions on the reduction of liver fat content and metabolic syndrome (MetS), and whether such reductions would influence renal outcomes, we conducted a randomized controlled trial on 128 participants with MetS and non-alcoholic fatty liver disease (NAFLD), as well as available data on estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatine ratio (UACR). Patients were randomized in 1:1:1 ratio to either Conventional Diet, Mediterranean diet (MD)-high meal frequency, and MD-physical activity groups. Each intervention aimed at reducing caloric intake by 25%-30% of baseline intake and increase energy expenditure by 400 kcal/70 kg. Patients attended regular visits and were followed-up for 6 months. Increased albuminuria was present in 13.3% of patients, while 32.8% showed hyperfiltration. UACR reduction was associated with higher levels of UACR at baseline but not with changes in liver fat. eGFR decreased in patients presenting hyperfiltration at baseline and was associated with reduction in liver fat and insulin resistance, as well as with increase in energy expenditure (R2 = 0.248, p = 0.006). No significant differences were observed between the three treatment groups. In patients with NAFLD and MetS, energy expenditure significantly reduced hepatic fat accumulation and insulin resistance, which reduced glomerular hyperfiltration. Increased albuminuria was reduced, but it was not associated with reduced liver fat.

Prospects for improved glomerular filtration rate estimation based on creatinine-results from a transnational multicentre study

BACKGROUND

The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine equation is routinely used to assess renal function but exhibits varying accuracy depending on patient characteristics and clinical presentation. The overall aim of the present study was to assess if and to what extent glomerular filtration rate (GFR) estimation based on creatinine can be improved.

METHODS

In a cross-sectional analysis covering the years 2003-17, CKD-EPI was validated against measured GFR (mGFR; using various tracer methods) in patients with high likelihood of chronic kidney disease (CKD; five CKD cohorts, n = 8365) and in patients with low likelihood of CKD (six community cohorts, n = 6759). Comparisons were made with the Lund-Malmö revised equation (LMR) and the Full Age Spectrum equation.

RESULTS

7In patients aged 18-39 years old, CKD-EPI overestimated GFR with 5.0-16 mL/min/1.73 m2 in median in both cohort types at mGFR levels <120 mL/min/1.73 m2. LMR had greater accuracy than CKD-EPI in the CKD cohorts (P30, the percentage of estimated GFR within 30% of mGFR, 83.5% versus 76.6%). CKD-EPI was generally the most accurate equation in the community cohorts, but all three equations reached P30 above the Kidney Disease Outcomes Quality Initiative benchmark of 90%.

CONCLUSIONS

None of the evaluated equations made optimal use of available data. Prospects for improved GFR estimation procedures based on creatinine exist, particularly in young adults and in settings where patients with suspected or manifest CKD are investigated.

Nighttime blood pressure decline as a predictor of renal injury in patients with hypertension: a population-based cohort study

We explored whether the nighttime blood pressure (BP) decline predicts renal function decline in a population-based cohort with primary hypertension. We measured the baseline ambulatory BP and glomerular filtration rate (GFR) in a cohort of 1,042 primary hypertensive patients. We repeated the GFR measurements and calculated the rate of GFR decline after a median follow-up of 5.8 years. The estimated GFR (eGFR) declined by -0.23 to -0.20 mL/min per year as the nighttime systolic BP (SBP), diastolic BP (DBP), and mean BP decline rates increased by 1% (P < 0.001). In the fully adjusted model, the nighttime SBP, DBP, and mean BP were all related to a steeper rate of eGFR decline by -0.25 to -0.22 mL/min per 1% increase. The adjusted multivariable results indicated that the odds of an eGFR decline were reduced by 46% when the nighttime SBP decline rate increased by 1% (OR= 0.54, 95% CI: 0.46-0.62). The restricted cubic spline model indicated a non-linear dose-response relationship with the nighttime SBP, DBP, and mean BP. Nighttime BP may be an important biomarker of renal function injury in hypertensive patients.

Glomerular Hyperfiltration Is Associated with Liver Disease Severity in Children with Nonalcoholic Fatty Liver Disease

OBJECTIVES

To determine the prevalence of renal impairment in a large cohort of youths with histologically confirmed nonalcoholic fatty liver disease (NAFLD), and to determine its association with liver disease severity.

STUDY DESIGN

Clinical, laboratory, and histology data were collected retrospectively in a pediatric cohort with biopsy-confirmed NAFLD at a tertiary care center between 2010 and 2017. Histological NAFLD severity was scored using validated criteria. Glomerular filtration rate (GFR) was calculated and categorized as low (<90 mL/min/1.73 m²), normal (90-136 mL/min/1.73 m²), or high (>136 mL/min/1.73 m²). Univariate and multivariate modeling were used to determine differences between the GFR groups and to control for confounders.

RESULTS

The cohort comprised 179 patients (82% non-Hispanic; median age; 14 years; IQR, 12-16 years). One-third of the patients had abnormal renal function, including 36 (20%) with glomerular hyperfiltration and 26 (15%) with low GFR. In multivariable logistic regression, compared with normal GFR, hyperfiltration was independently associated with higher NAFLD activity score (aOR, 2.96; 95% CI, 1.49-5.87; P = .002), after adjusting for age, sex, ethnicity, obesity severity, presence of type 2 diabetes mellitus, and medications.

CONCLUSIONS

In this large cohort with histologically confirmed NAFLD, renal impairment was highly prevalent and associated with liver disease severity, independent of obesity severity. Screening patients with confirmed NAFLD for renal complication is recommended.

Association between Depression and Renal Hyperfiltration in a General Chinese Population

BACKGROUND

Depression is prevalent in patients with all stages of CKD and is associated with adverse outcome. Abnormally elevated GFR, or hyperfiltration, may play a crucial role in the initiation and progression of CKD. However, the association between depression and hyperfiltration is not known. The aim of this study is to investigate the relationship between depression and hyperfiltration.

METHODS

This was an observational cross-sectional study. A total of 3,716 volunteers (1,303 males and 2,413 females) aged 40-75 years without CKD from a community in China were included for the study. Depressive symptoms and the presence of a minor or major depressive episode were assessed with the 9-item Patient Health Questionnaire (PHQ-9) and Diagnostic and Statistical Manual of Mental Disorders (4th edition)-based structured interview, respectively.

RESULTS

The mean age of the participants in the present study was 53.8 ± 9.0 years. 115 participants had clinically relevant depression, and 122 participants had a minor or major depressive episode. In a multivariable logistic regression analysis adjusted for potential confounders, the association between clinically relevant depression and renal hyperfiltration remained significant in men but not in women. As compared with men without depression (PHQ <5) or depressive episodes, those with clinically relevant depression (PHQ ≥10) had a significantly higher risk of renal hyperfiltration. The fully adjusted OR (95% CI) was 4.81 (1.62-14.30, p = 0.005), those with a major depressive episode had a higher risk of renal hyperfiltration (OR 7.45; 95% CI 2.04-27.21, p = 0.002).

CONCLUSION

Depressive symptoms and major depressive episodes are associated with renal hyperfiltration in middle-aged and elderly Chinese men without CKD. Future studies are needed to verify and clarify the role of depression in the development of abnormally high eGFR and CKD.

Severe vitamin D deficiency is a risk factor for renal hyperfiltration

Background

Vitamin D deficiency is associated with renal progression in chronic kidney disease. Moreover, improvement of clinical outcomes after vitamin D supplementation has been reported in the diabetic and chronic kidney disease population.

Objective

We investigated the association between renal hyperfiltration (RHF) and vitamin D status in a relatively healthy population.

Design

Data were retrieved from the Korean NHANES, a nationwide population-based cross-sectional study from 2008 to 2015. Overall, 33,210 subjects with normal renal function were included in the final analysis. Severe vitamin D deficiency was defined as serum 25-hydroxyvitamin D concentration <10 ng/mL. RHF was defined as estimated glomerular filtration rate with residual in the >95th percentile after adjustment for age, sex, height, weight, and history of hypertension or diabetes.

Results

The mean ± SD age of subjects was 48.1 ± 15.9 y, and the number of women was 18,779 (56.5%). Estimated glomerular filtration rate was negatively associated with serum 25-hydroxyvitamin D concentrations in multivariable linear regression analysis (β: -0.02; 95% CI: -0.02, -0.01; P < 0.001). Furthermore, 1637 (4.9%) subjects were categorized into the RHF group, and the prevalence of RHF was significantly higher in the severe vitamin D deficiency group than in the sufficiency group (5.8% compared with 5.0%, P < 0.001). In a multivariable logistic regression model, severe vitamin D deficiency was a significant risk factor for RHF (OR: 2.41; 95% CI, 1.72, 3.43; P < 0.001).

Conclusions

Severe vitamin D deficiency is significantly associated with increasing prevalence of RHF in a relatively healthy adult population.

Different association between renal hyperfiltration and mortality by sex

AIM

Renal hyperfiltration (RHF) is a marker of early kidney injury that was recently shown to be a novel marker of mortality. However, it has no clear definition. In this study, we suggested an age- and sex-adjusted RHF definition and explored the association between RHF and mortality by sex.

METHODS

We analyzed data from individuals receiving routine health examinations from 1995 to 2009. RHF was defined as an estimated glomerular filtration rate over the 95th percentile matched for age and sex.

RESULTS

A total of 114 966 individuals were included. During the 75-month of observation period, 2559 (2.2%) participants died. Among those, 71.4% were men. Because sex and RHF had a significant interaction for mortality (P for interaction < 0.001), we performed survival analysis according to sex. RHF was related to lower body weight and a higher proportion of cigarette smoking in men, whereas these relationships were not found in women. In the Kaplan-Meier curve, RHF was associated with higher mortality rate than non-RHF in both sexes, but this relationship was more prominent in men. In the multivariate analysis, RHF remained as an independent risk factor for all-cause mortality even after adjustment for confounding in men (hazard ratio, 1.34; 95% confidence interval, 1.12-1.59; P = 0.001). In women, RHF was not associated with increased mortality.

CONCLUSIONS

We demonstrated that RHF was a significant risk factor for mortality in men but not in women. The mechanisms and clinical implications of these different associations according to sex require a further clarification.

Association of renal hyperfiltration with incident proteinuria - A nationwide registry study

To elucidate the association between renal hyperfiltration (RHF) and incident proteinuria, the data from 11,559,520 Korean adults who had undergone health screenings ≥ 3 times between 2009 and 2014 and had glomerular filtration rate (GFR) ≥60 mL/min/1.73m2 and negative dipstick test for proteinuria at baseline, were retrospectively analyzed. GFR was estimated with the Chronic Kidney Disease Epidemiology Collaboration equation based on serum creatinine, and RHF was defined as GFR >95th percentile adjusted for sex, age, body size, and diabetes and/or hypertension medication. The adjusted hazard ratio (aHR) of incident proteinuria in the RHF was 1.083 (95% CI, 1.069~1.097) compared to that of the non-RHF with Cox regression model. The association between RHF and incident proteinuria was not only in diabetic but also in non-diabetic subjects. This association was not observed in women (p for interaction <0.001). A reverse J-shaped association was found between the adjusted GFR slope and aHR of incident proteinuria. Both lower and higher GFR were associated with incident proteinuria in men. In conclusion, RHF was associated with incident proteinuria in men. Clinical studies are necessary to study whether the alleviation of RHF can prevent incident proteinuria.

Life with one kidney

Life with a solitary functioning kidney (SFK) may be different from that when born with two kidneys. Based on the hyperfiltration hypothesis, a SFK may lead to glomerular damage with hypertension, albuminuria and progression towards end-stage renal disease. As the prognosis of kidney donors was considered to be very good, having a SFK has been considered to be a benign condition. In contrast, our research group has demonstrated that being born with or acquiring a SFK in childhood results in renal injury before adulthood in over 50% of those affected. Most congenital cases will be detected during antenatal ultrasound screening, but up to 38% of cases of unilateral renal agenesis are missed. In about 25-50% of cases of antenatally detected SFK there will be signs of hypertrophy, which could indicate additional nephron formation and is associated with a somewhat reduced risk of renal injury. Additional renal and extrarenal anomalies are frequently detected and may denote a genetic cause for the SFK, even though for the majority of cases no explanation can (yet) be found. The ongoing glomerular hyperfiltration results in renal injury, for which early markers are lacking. Individuals with SFK should avoid obesity and excessive salt intake to limit additional hyperfiltration. As conditions like hypertension, albuminuria and a mildly reduced glomerular filtration rate generally do not result in specific complaints but may pose a threat to long-term health, screening for renal injury in any individual with a SFK would appear to be imperative, starting from infancy. With early treatment, secondary consequences may be diminished, thereby providing the optimal life for anyone born with a SFK.

The effect of high-dose vitamin D3 supplementation on bone mineral density in subjects with prediabetes

The rationale of this study was to determine the effect of high-dose vitamin D₃ supplementation on bone mineral density (BMD). Prediabetic males given vitamin D had significantly less reduction in BMD at the femoral neck compared to the controls. The clinical implications of our findings require further investigation.

INTRODUCTION

Type 2 diabetes mellitus is associated with increased fracture risk, and recent studies show crosstalk between bone and glucose metabolism. Few studies have investigated the effect of vitamin D supplementation on the bone without additional calcium. In the present study, we aimed to determine whether a high dose of vitamin D₃ could improve bone mass density (BMD) in prediabetic subjects.

METHODS

The current study was conducted as a secondary research on a previously performed trial, in which 511 subjects with prediabetes were randomized to vitamin D₃ (20,000 IU per week) versus placebo for 5 years. BMD was measured using dual-energy X-ray absorptiometry (DEXA).

RESULTS

Two hundred and fifty-six subjects were randomized to vitamin D and 255 to placebo. Mean baseline serum 25-hydroxyvitamin D (25(OH)D) level was 60 nmol/L. Two hundred and two and 214 in the vitamin D and placebo groups, respectively, completed BMD measurements, whereas one in each group was excluded due to use of bisphosphonates. Males given vitamin D had significantly less reduction in BMD at the femoral neck measurement site compared to the controls (0.000 versus - 0.010 g/cm², p = 0.008). No significant differences between intervention groups were seen at the total hip measurement site, regarding both males and females.

CONCLUSIONS

Vitamin D₃ supplementation alone may be beneficial in males with prediabetes, but confirmatory studies are needed.

Renal function and attributable risk of death and cardiovascular hospitalization in patients with cardiovascular risk factors from a registry-based cohort: the Estudio Cardiovascular Valencia-risk study

BACKGROUND

Information about the attributable risk associated with renal dysfunction in patients with cardiovascular risk factors is lacking.

OBJECTIVE

We aimed to estimate the attributable risk associated with chronic kidney disease Epidemiology Collaboration-estimated glomerular filtration rate (eGFR), for all-cause mortality, and cardiovascular hospitalization.

DESIGN, SETTING, AND PARTICIPANTS

Prospective study of study participants with cardiovascular risk factors in 2008-2012. We included 52 007 cardiovascular disease-free men and women aged 30 years or older with hypertension, diabetes, or dyslipidemia, who underwent routine health examinations in primary care.

RESULTS

A total of 6639 (12.8%) patients had eGFR below 60 ml/min per 1.73 m and among them 1782 (3.4%) had 45 ml/min per 1.73 m or lower. During an average follow-up time of 3.2 years, 54.12 deaths, 99.98 coronary heart disease (CHD) hospitalizations, and 90.64 stroke hospitalizations/10 000 person-years were recorded. The population attributable risks associated with having a GFR lower than 60 ml/min per 1.73 m were 6.9% (95% confidence interval = 2.07, 10.65) for all-cause mortality, 6.8% (4.3, 9.4) for CHD hospitalization, and 4.1% (1.02, 7.00) for stroke hospitalization. Participants with increasing number of cardiovascular risk factors displayed increasing population attributable risks associated to a GFR less than 60 ml/min per 1.73 m for all-cause mortality and CHD (P heterogeneity 0.002 and 0.05, respectively).

CONCLUSION

In a large general practice cohort of patients with cardiovascular disease risk factors, decreasing eGFR levels were associated with additional attributed risk of mortality and cardiovascular disease. Our findings underscore that intensified efforts are needed to reduce the cardiovascular disease burden associated to chronic kidney disease.

Establishing the presence or absence of chronic kidney disease: Uses and limitations of formulas estimating the glomerular filtration rate

The development of formulas estimating glomerular filtration rate (eGFR) from serum creatinine and cystatin C and accounting for certain variables affecting the production rate of these biomarkers, including ethnicity, gender and age, has led to the current scheme of diagnosing and staging chronic kidney disease (CKD), which is based on eGFR values and albuminuria. This scheme has been applied extensively in various populations and has led to the current estimates of prevalence of CKD. In addition, this scheme is applied in clinical studies evaluating the risks of CKD and the efficacy of various interventions directed towards improving its course. Disagreements between creatinine-based and cystatin-based eGFR values and between eGFR values and measured GFR have been reported in various cohorts. These disagreements are the consequence of variations in the rate of production and in factors, other than GFR, affecting the rate of removal of creatinine and cystatin C. The disagreements create limitations for all eGFR formulas developed so far. The main limitations are low sensitivity in detecting early CKD in several subjects, e.g., those with hyperfiltration, and poor prediction of the course of CKD. Research efforts in CKD are currently directed towards identification of biomarkers that are better indices of GFR than the current biomarkers and, particularly, biomarkers of early renal tissue injury.

Glomerular hyperfiltration is a predictor of adverse cardiovascular outcomes

The association between glomerular hyperfiltration and cardiovascular events is not well known. To investigate whether glomerular hyperfiltration is independently associated with risk of adverse outcome we analyzed 8794 participants, average age 52 years enrolled in 8 prospective studies. Of these, 89% had hypertension. Using the 5th and 95th percentiles of the age- and sex-specific quintiles of CKD-EPI-calculated estimated glomerular filtration rate (eGFR), we identified three participant groups with low, high and normal eGFR. The ambulatory pulse pressure interval was wider and nighttime blood pressure fall was smaller in both the low and high than in the normal eGFR participants. During a mean follow-up of 6.2 years, there were 722 cardiovascular events. Crude event rates were significantly higher for both high (1.8 per 100-person-year) and low eGFR groups (2.1 per 100 person-year) as compared with group with normal eGFR (1.2 per 100 person-year). In multivariable Cox models including age, sex, average 24-hour blood pressure, smoking, diabetes, and cholesterol, both high eGFR (hazard ratio 1.5 (95% confidence interval 1.2-2.1) and low eGFR (2.0 [1.5-2.6]) participants had a significantly higher risk of cardiovascular events as compared to those with normal eGFR. Addition of body mass index to the multivariable survival model did not change the magnitude of hazard estimates. Thus, glomerular hyperfiltration is a strong and independent predictor of cardiovascular events in a large multiethnic population of predominantly hypertensive individuals. Our findings support a U-shaped relationship between eGFR and adverse outcome.

Association of Increasing GFR with Change in Albuminuria in the General Population

BACKGROUND AND OBJECTIVES

Hyperfiltration at the single-nephron level has been proposed as an early stage of kidney dysfunction of different origins. Evidence supporting this hypothesis in humans is lacking, because there is no method of measuring single-nephron GFR in humans. However, increased whole-kidney GFR in the same individual implies an increased single-nephron GFR, because the number of nephrons does not increase with age. We hypothesized that an increase in GFR would be associated with an increased albumin-to-creatinine ratio in a cohort of the general population.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We measured GFR by iohexol clearance at baseline in 2007-2009 and follow-up after 5.6 years in a representative sample of 1246 persons (aged 50-62 years) who were nondiabetic from the general population of Tromso, northern Norway. Participants were without cardiovascular disease, kidney disease, or diabetes at baseline. We investigated the association between change in GFR and change in albumin-to-creatinine ratio. Increased GFR was defined as a positive change in GFR (change in GFR>0 ml/min) from baseline to follow-up. An albumin-to-creatinine ratio >30 mg/g was classified as albuminuria.

RESULTS

Change in GFR was positively associated with a change in albumin-to-creatinine ratio in the entire cohort in the multiple linear regression. The albumin-to-creatinine ratiofollow-up-to-albumin-to-creatinine ratiobaseline ratio increased by 8.0% (95% confidence interval, 1.4 to 15.0) per SD increase in change in GFR. When participants with increased GFR (n=343) were compared with those with a reduced GFR (n=903), the ratio increased by 16.3% (95% confidence interval, 1.1 to 33.7). The multivariable adjusted odds ratio for incident albuminuria (n=14) was 4.98 (95% confidence interval, 1.49 to 16.13) for those with an increased GFR (yes/no).

CONCLUSIONS

Increasing GFR is associated with an increase in albumin-to-creatinine ratio and incident albuminuria in the general nondiabetic population. These findings support single-nephron hyperfiltration as a risk factor for albuminuria in the general population.

The Association between Renal Hyperfiltration and the Sources of Habitual Protein Intake and Dietary Acid Load in a General Population with Preserved Renal Function: The KoGES Study

Although the differential response of the kidney to the acute load of various sources of dietary protein in subjects with normal renal function is well known, the influence of habitual dietary protein intake and dietary acid load on renal function has not been tested well. The association between renal hyperfiltration (RHF), the earlier and possibly reversible stage of chronic kidney disease, and the sources of habitual dietary protein and dietary acid load was analyzed with the baseline data of 123,169 middle-aged healthy Koreans of a large prospective cohort study, who had a baseline estimated glomerular filtration rate (eGFR) >60 mL/min/m2 and no known history of diabetes and/or hypertension. eGFR was calculated with the Chronic Kidney Disease Epidemiology Collaboration equation using serum creatinine and RHF was defined as eGFR >95th percentile after adjustment for age, sex, height, and body weight. Dietary acid load was calculated with estimated net endogenous acid production (eNEAP). Although the level of habitual intake of animal protein was positively and vegetable protein was negatively associated with RHF, this association was significant only in women and younger participants (younger than sex-specific median age). The odds for RHF increased as the percentile rank of eNEAP increased until about the 50th percentile and then leveled off. The positive association between eNEAP and RHF was significant in both sexes and age groups. Dietary acid load was associated with RHF regardless of sex and age and rather than the amount of the total or the individual sources of habitual dietary protein, may be a better target for the dietary intervention of chronic kidney disease.

Vitamin D 20,000 IU per Week for Five Years Does Not Prevent Progression From Prediabetes to Diabetes

CONTEXT

Vitamin D deficiency is associated with insulin resistance and risk of future diabetes.

OBJECTIVE

The objective of the study was to test whether supplementation with vitamin D to subjects with prediabetes will prevent progression to type 2 diabetes mellitus (T2DM).

DESIGN

This was a randomized controlled trial performed in 2008 through 2015.

SETTING

The study was conducted at the clinical research unit at a teaching hospital.

PATIENTS

Five hundred eleven subjects (mean age 62 y, 314 males) with prediabetes diagnosed with an oral glucose tolerance test as part of the Tromsø Study 2007–2008 were included. A total of 256 were randomized to vitamin D and 255 to placebo. Twenty-nine subjects in the vitamin D and 24 in the placebo group withdrew because of adverse events.

INTERVENTIONS

Interventions included vitamin D (cholecalciferol) 20 000 IU/wk vs placebo for 5 years. Annual oral glucose tolerance tests were performed.

MAIN OUTCOME MEASURE

Progression to T2DM was the main outcome measure. Secondary outcomes were change in glucose levels, insulin resistance, serum lipids, and blood pressure.

RESULTS

The mean baseline serum 25-hydroxyvitamin D level was 60 nmol/L (24 ng/mL). One hundred three in the vitamin D and 112 in the placebo group developed T2DM (hazard risk 0.90; 95% confidence interval 0.69–1.18, Cox regression, P = .45, intention to treat analysis). No consistent significant effects on the other outcomes were seen. Subgroup analyses in subjects with low baseline 25-hydroxyvitamin D yielded similar results. No serious side effects related to the intervention were recorded.

CONCLUSIONS

In subjects without vitamin D deficiency, vitamin D supplementation is unlikely to prevent progression from prediabetes to diabetes. Very large studies with inclusion of vitamin D-deficient subjects will probably be needed to show such a putative effect. This study tested if supplementation with vitamin D to subjects with prediabetes will prevent progression to type 2 diabetes (T2DM).

An estimated glomerular filtration rate equation for the full age spectrum

BACKGROUND

Glomerular filtration rate (GFR) is accepted as the best indicator of kidney function and is commonly estimated from serum creatinine (SCr)-based equations. Separate equations have been developed for children (Schwartz equation), younger and middle-age adults [Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation] and older adults [Berlin Initiative Study 1 (BIS1) equation], and these equations lack continuity with ageing. We developed and validated an equation for estimating the glomerular filtration rate that can be used across the full age spectrum (FAS).

METHODS

The new FAS equation is based on normalized serum creatinine (SCr/Q), where Q is the median SCr from healthy populations to account for age and sex. Coefficients for the equation are mathematically obtained by requiring continuity during the paediatric-adult and adult-elderly transition. Research studies containing a total of 6870 healthy and kidney-diseased white individuals, including 735 children, <18 years of age, 4371 adults, between 18 and 70 years of age, and 1764 older adults, ≥70 years of age with measured GFR (inulin, iohexol and iothalamate clearance) and isotope dilution mass spectrometry-equivalent SCr, were used for the validation. Bias, precision and accuracy (P30) were evaluated.

RESULTS

The FAS equation was less biased [-1.7 (95% CI -3.4, -0.2) versus 6.0 (4.5, 7.5)] and more accurate [87.5% (85.1, 89.9) versus 83.8% (81.1, 86.5)] than the Schwartz equation for children and adolescents; less biased [5.0 (4.5, 5.5) versus 6.3 (5.9, 6.8)] and as accurate [81.6% (80.4, 82.7) versus 81.9% (80.7, 83.0)] as the CKD-EPI equation for young and middle-age adults; and less biased [-1.1 (-1.6, -0.6) versus 5.6 (5.1, 6.2)] and more accurate [86.1% (84.4, 87.7) versus 81.8% (79.7, 84.0)] than CKD-EPI for older adults.

CONCLUSIONS

The FAS equation has improved validity and continuity across the full age-spectrum and overcomes the problem of implausible eGFR changes in patients which would otherwise occur when switching between more age-specific equations.

Association between lower serum bicarbonate and renal hyperfiltration in the general population with preserved renal function: a cross-sectional study

Background

Lower serum bicarbonate, mainly due to the modern Western-style diet, and renal hyperfiltration (RHF) are both independently associated with higher mortality in the general population with preserved renal function. The objective of this study was to evaluate the association between serum bicarbonate and RHF.

Methods

The health data of 41,886 adults with an estimated glomerular filtration rate (eGFR) ≥60 mL/min per 1.73 m² were analyzed. The eGFR was calculated with the Chronic Kidney Disease Epidemiology Collaboration creatinine equation and RHF was defined as eGFR with adjusted residuals > sex-specific 95^th percentile.

Results

The adjusted mean of eGFR was lower in the highest quintile of serum bicarbonate than in other quintiles, after adjusting for confounders. A lower percentile rank of serum bicarbonate was associated with higher odds of RHF. The odds ratio (OR) for RHF in the lowest quintile of serum bicarbonate was 1.39 (95 % confidence interval, 95 % CI, 1.11–1.75) compared to the highest, after adjusting for confounders. With subgroup analysis, the association was prominent in participants with a body mass index >25 kg/m² (OR 1.98, 95 % CI 1.32–2.95 in the lowest quintile compared to the highest), compared to those with a body mass index ≤25 kg/m² (OR 1.18, 95 % CI 0.89–1.56 in the lowest quintile compared to the highest).

Conclusions

This study observed an association between lower serum bicarbonate and higher odds of RHF and the possible differential effect of obesity in this association. It is necessary to confirm the association between lower serum bicarbonate and RHF and its causality.

Prediabetes and Risk of Glomerular Hyperfiltration and Albuminuria in the General Nondiabetic Population: A Prospective Cohort Study

BACKGROUND

The role of prediabetes as a risk factor for hyperfiltration and albuminuria in persons who do not develop diabetes is unclear. The lack of evidence is mainly due to the difficulty of accurately assessing the glomerular filtration rate (GFR) in the near-normal range of GFR. We investigated whether prediabetes is an independent risk factor for glomerular hyperfiltration and high-normal urinary albumin-creatinine ratio (ACR) using measured GFR (mGFR) rather than estimated GFR.

STUDY DESIGN

Prospective cohort study based on the Renal Iohexol Clearance Survey in Tromsø 6 (RENIS-T6) and the RENIS Follow-Up Study. Median observation time was 5.6 years.

SETTING & PARTICIPANTS

A representative sample of 1,261 persons without diabetes mellitus (DM) from the general population aged 50 to 62 years.

PREDICTOR

Prediabetes defined by fasting glucose and hemoglobin A1c according to levels suggested by the American Diabetes Association (preDMADA) and the International Expert Committee of 2009 (preDMIEC).

OUTCOMES

Change in mGFR; hyperfiltration defined as mGFR>90th percentile adjusted for age, sex, weight, and height; and high-normal ACR (>10mg/g) at follow-up.

MEASUREMENTS

GFR was measured with iohexol clearance.

RESULTS

Baseline fasting glucose, hemoglobin A1c, and both definitions of prediabetes were predictors of higher mGFR at follow-up and lower annual mGFR decline in multivariable-adjusted regression analyses. Participants with preDMIEC had an OR for hyperfiltration of 1.95 (95% CI, 1.20-3.17) and for high-normal ACR of 1.83 (95% CI, 1.04-3.22) at follow-up. We adjusted for cardiovascular risk factors including ambulatory blood pressure at baseline and change in use of antihypertensive medication between baseline and follow-up.

LIMITATIONS

Only middle-aged white patients participated. There is no consensus on how to define glomerular hyperfiltration.

CONCLUSIONS

Our findings imply an independent role of prediabetes in the development of glomerular hyperfiltration and albuminuria. Prediabetes might be a target for early treatment to prevent chronic kidney disease in chronic hyperglycemia.

Residual Associations of Inflammatory Markers with eGFR after Accounting for Measured GFR in a Community-Based Cohort without CKD

BACKGROUND AND OBJECTIVES

eGFR on the basis of creatinine (eGFRcre) associates differently with cardiovascular disease and mortality than eGFR on the basis of cystatin C (eGFRcys). This may be related to risk factors affecting the level of creatinine and cystatin C along non-GFR pathways, which may confound the association between eGFR and outcome. Nontraditional risk factors are usually not measured in epidemiologic studies of eGFR and cannot be adjusted for to reduce confounding. We examined whether the inflammatory markers soluble TNF receptor type 2 (sTNFR2), C-reactive protein (CRP), and fibrinogen associated differently with eGFR than with measured GFR (mGFR).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

GFR was measured by iohexol clearance in 1627 middle-aged participants without kidney disease, diabetes, or cardiovascular disease enrolled in the Renal Iohexol Clearance Survey Study from the Sixth Tromsø Study between 2007 and 2009. Generalized estimating equations were used to assess the residual associations between eGFR (eGFRcre, eGFRcys, and eGFR on the basis of creatinine and cystatin C) and the inflammatory markers relative to mGFR.

RESULTS

sTNFR2, CRP, and fibrinogen were associated with a higher eGFRcre after accounting for mGFR in multivariable-adjusted models (2.63 ml/min per 1.73 m(2); 95% confidence interval [95% CI], 2.1 to 3.2 per SD increase in sTNFR2, 0.93 ml/min per 1.73 m(2); 95% CI, 0.3 to 1.5 per SD increase in log CRP, and 1.19 ml/min per 1.73 m(2); 95% CI, 0.6 to 1.8 per SD increase in fibrinogen). sTNFR2 and CRP were inversely associated with eGFRcys (-1.4 ml/min per 1.73 m(2); 95% CI, -2.1 to -0.6 per SD increase in sTNFR2, and -0.76 ml/min per 1.73 m(2); 95% CI, -1.4 to -0.1 per SD increase in log CRP).

CONCLUSIONS

eGFRcre and eGFRcys are associated with inflammatory factors after accounting for mGFR but in opposite directions. These non-GFR-related associations may bias risk estimates by eGFR and, in part, explain the different risks predicted by eGFRcre and eGFRcys in longitudinal studies.

Renal endothelial dysfunction in diabetic nephropathy

Endothelial dysfunction has been posited to play an important role in the pathogenesis of diabetic nephropathy (DN). Due to the heterogeneity of endothelial cells (ECs), it is difficult to generalize about endothelial responses to diabetic stimuli. At present, there are limited techniques fordirectly measuring EC function in vivo, so diagnosis of endothelial disorders still largely depends on indirect assessment of mediators arising from EC injury. In the kidney microcirculation, both afferent and efferent arteries, arterioles and glomerular endothelial cells (GEnC) have all been implicated as targets of diabetic injury. Both hyperglycemia per se, as well as the metabolic consequences of glucose dysregulation, are thought to lead to endothelial cell dysfunction. In this regard, endothelial nitric oxide synthase (eNOS) plays a central role in EC dysfunction. Impaired eNOS activity can occur at numerous levels, including enzyme uncoupling, post-translational modifications, internalization and decreased expression. Reduced nitric oxide (NO) bioavailability exacerbates oxidative stress, further promoting endothelial dysfunction and injury. The injured ECs may then function as active signal transducers of metabolic, hemodynamic and inflammatory factors that modify the function and morphology of the vessel wall and interact with adjacent cells, which may activate a cascade of inflammatory and proliferative and profibrotic responses in progressive DN. Both pharmacological approaches and potential regenerative therapies hold promise for restoration of impaired endothelial cells in diabetic nephropathy.

Estimated GFR is biased by non-traditional cardiovascular risk factors

BACKGROUND

Estimated glomerular filtration rate (eGFR) based on either cystatin C or creatinine performs similarly in estimating measured GFR, but associate differently with cardiovascular disease (CVD) and mortality. This could be due to confounding by non-GFR-related traits associated with cystatin C and creatinine levels. We investigated non-GFR-related associations between eGFR and two types of nontraditional risk factors for CVD and death: L-arginine/dimethylarginine metabolism and insulin resistance.

METHODS

GFR was measured via iohexol clearance in a cross-sectional study of 1,624 middle-aged persons from the general population without CVD, diabetes or chronic kidney disease. The dimethylarginines were measured using liquid chromatography tandem mass spectrometry (LC-MSMS). Insulin resistance was determined by the homeostasis model assessment (HOMA-IR).

RESULTS

Asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), the L-arginine/ADMA ratio and insulin resistance were associated with creatinine-based eGFR after accounting for measured GFR in multivariable adjusted analyses. The cystatin C-based eGFR showed a similar residual association with SDMA; an oppositely directed, borderline significant association with ADMA; and a stronger residual association with insulin resistance compared with eGFR based on creatinine.

CONCLUSION

Both creatinine- and cystatin C-based eGFR are influenced by nontraditional risk factors, which may bias risk prediction by eGFR in longitudinal studies.

Renal hyperfiltration as a novel marker of all-cause mortality

Although renal hyperfiltration (RHF) or an abnormal increase in GFR has been associated with many lifestyles and clinical conditions, including diabetes, its clinical consequence is not clear. RHF is frequently considered to be the result of overestimating true GFR in subjects with muscle wasting. To evaluate the association between RHF and mortality, 43,503 adult Koreans who underwent voluntary health screening at Seoul National University Hospital between March of 1995 and May of 2006 with baseline GFR≥60 ml/min per 1.73 m(2) were followed up for mortality until December 31, 2012. GFR was estimated with the Chronic Kidney Disease Epidemiology Collaboration creatinine equation, and RHF was defined as GFR>95th percentile after adjustment for age, sex, muscle mass, and history of diabetes and/or hypertension medication. Muscle mass was measured with bioimpedance analysis at baseline. During the median follow-up of 12.4 years, 1743 deaths occurred. The odds ratio of RHF in participants with the highest quartile of muscle mass was 1.31 (95% confidence interval [95% CI], 1.11 to 1.54) compared with the lowest quartile after adjusting for confounding factors, including body mass index. The hazard ratio of all-cause mortality for RHF was 1.37 (95% CI, 1.11 to 1.70) by Cox proportional hazards model with adjustment for known risk factors, including smoking. These data suggest RHF may be associated with increased all-cause mortality in an apparently healthy population. The possibility of RHF as a novel marker of all-cause mortality should be confirmed.

No effect of high-dose vitamin D supplementation on glycemic status or cardiovascular risk factors in subjects with prediabetes

OBJECTIVE

In observational studies, low serum 25-hydroxyvitamin D [25(OH)D] concentrations have been associated with insulin resistance and other risk factors for cardiovascular disease.

RESEARCH DESIGN AND METHODS

We present 1-year data from an ongoing 5-year trial in 511 individuals with impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) randomly assigned to 20,000 IU/week vitamin D3 or placebo. An oral glucose tolerance test was performed at baseline and after 1 year.

RESULTS

Mean baseline serum 25(OH)D was 59.9 nmol/L and 61.1 nmol/L in the vitamin D and placebo groups, respectively, and increased by 45.8 nmol/L and 3.4 nmol/L, respectively. With adjustment for baseline concentrations, no differences in measures of glucose metabolism, insulin secretion or sensitivity, blood pressure, or hs-CRP were found after 1 year. There was a slight, but significant decrease in total and LDL cholesterol in the vitamin D group compared with the placebo group, but as there was also a decrease in HDL cholesterol, the change in the total/HDL cholesterol ratio did not differ significantly. Only analyzing subjects with 25(OH)D <50 nmol/L did not change the results.

CONCLUSIONS

This study shows that vitamin D supplementation does not improve glycemic indices, blood pressure, or lipid status in subjects with IFG and/or IGT.