Twelve shifting paradigms in diabetic renal disease and hypertension

Relationship between High Level of Estimated Glomerular Filtration Rate and Contrast-Induced Acute Kidney Injury in Patients who Underwent an Emergency Percutaneous Coronary Intervention

Background

Mounts of studies have shown that low estimated glomerular filtration rate (eGFR) is associated with increased risk of adverse outcomes in patients with coronary artery disease. However, high level of eGFR was less reported. In the study, we aimed to explore the relationship between the baseline eGFR, especially the high level, and contrast-induced acute kidney injury (CI-AKI) in a Chinese population who underwent an emergency percutaneous coronary intervention (PCI).

Methods

Patients who underwent an emergency PCI from 2013 to 2015 were enrolled and divided into five groups as eGFR decreasing. Baseline characteristics were collected and analyzed. The rates of CI-AKI and the composite endpoint (including nonfatal myocardial infarction, revascularization, stroke, and all-cause death) at 6- and 12-month follow-up were compared. Logistic analysis for CI-AKI was performed.

Results

A total of 1061 patients were included and the overall CI-AKI rate was 22.7% (241/1061). The separate rates were 77.8% (7/9) in Group 1 (eGFR ≥120 ml·min^-1·1.73 m^-2), 26.0% (118/454) in Group 2 (120 ml·min^-1·1.73 m^-2> eGFR ≥90 ml·min^-1·1.73m^-2), 18.3% (86/469) in Group 3 (90 ml·min^-1·1.73 m^-2> eGFR ≥60 ml·min^-1·1.73 m^-2), 21.8% (26/119) in Group 4 (60 ml·min^-1·1.73 m^-2> eGFR ≥30 ml·min^-1·1.73 m^-2), and 40.0% (4/10) in Group 5 (eGFR <30 ml·min^-1·1.73 m^-2), with statistical significance (χ² = 25.19, P < 0.001). The rates of CI-AKI in five groups were 77.8%, 26.0%, 18.3%, 21.8%, and 40.0%, respectively, showing a U-typed curve as eGFR decreasing (the higher the level of eGFR, the higher the CI-AKI occurrence in case of eGFR ≥60 ml·min^-1·1.73 m^-2). The composite endpoint rates in five groups were 0, 0.9%, 2.1%, 6.7%, and 0 at 6-month follow-up, respectively, and 0, 3.3%, 3.4%, 16.0%, and 30.0% at 12-month follow-up, respectively, both with significant differences (χ² = 16.26, P = 0.009 at 6-month follow-up, and χ² = 49.05, P < 0.001 at 12-month follow-up). The logistic analysis confirmed that eGFR was one of independent risk factors of CI-AKI in emergency PCI patients.

Conclusions

High level of eGFR might be associated with increased risk of CI-AKI in patients with emergency PCI, implying for future studies and risk stratification in clinical practice.

mTORC1 inhibitors rapamycin and metformin affect cardiovascular markers differentially in ZDF rats

Mammalian target for rapamycin complex 1 (mTORC1) is a common target for the action of immunosuppressant macrolide rapamycin and glucose-lowering metformin. Inhibition of mTORC1 can exert both beneficial and detrimental effects in different pathologies. Here, we investigated the differential effects of rapamycin (1.2 mg/kg per day delivered subcutaneously for 6 weeks) and metformin (300 mg/kg per day delivered orally for 11 weeks) treatments on male Zucker diabetic fatty (ZDF) rats that mimic the cardiorenal pathology of type 2 diabetic patients and progress to insulin insufficiency. Rapamycin and metformin improved proteinuria, and rapamycin also reduced urinary gamma glutamyl transferase (GGT) indicating improvement of tubular health. Metformin reduced food and water intake, and urinary sodium and potassium, whereas rapamycin increased urinary sodium. Metformin reduced plasma alkaline phosphatase, but induced transaminitis as evidenced by significant increases in plasma AST and ALT. Metformin also induced hyperinsulinemia, but did not suppress fasting plasma glucose after ZDF rats reached 17 weeks of age, and worsened lipid profile. Rapamycin also induced mild transaminitis. Additionally, both rapamycin and metformin increased plasma uric acid and creatinine, biomarkers for cardiovascular and renal disease. These observations define how rapamycin and metformin differentially modulate metabolic profiles that regulate cardiorenal pathology in conditions of severe type 2 diabetes.

Urinary albumin excretion and prevalence of microalbuminuria in a general Chinese population: a cross-sectional study

BACKGROUND

Microalbuminuria has been shown to be a risk factor for cardiovascular and renal disease in patients with hypertension and diabetes as well as in the general population. Urinary albumin excretion over 24 h is considered a 'gold standard' to detect microalbuminuria. Few studies have used 24-h urinary albumin excretion to analyze the prevalence of and related factors for microalbuminuira in a general Chinese population.

METHODS

This study included 1980 adults aged 18-69 years from the Shandong-Ministry of Health Action on Salt and Hypertension (SMASH) Project 2011 survey. Blood pressure, height, weight and waist circumference were measured, and a venous blood and timed 24-h urine samples were collected from each participant. Linear and logistic regression analyses were used to test associations between established cardiovascular risk factors and microalbuminuria.

RESULTS

The median (25th-75th percentile) of 24-h urinary albumin excretion was 6.1 mg/d (4.5-8.7 mg/d) for all adults, 6.0 mg/d (4.4-8.5 mg/d) for men and 6.2 mg/d (4.6-8.9 mg/d) for women. The overall prevalence of microalbuminuria was 4.1% (95% confidence interval [CI]: 3.2-5.0%), 3.7% (95% CI: 2.9-4.5%) for men and 4.6% (95% CI: 3.7-5.5%) for women. Microalbuminuria was present in 8.1% (95% CI: 6.9-9.3%) of individuals with hypertension, 11.4% (95% CI: 10.0-12.8%) of those with diabetes and 15.6% (95% CI: 14.0-17.2%) of those with both. Multiple logistic regression analysis indicated that systolic blood pressure (odds ratio [OR] 1.02; 95% CI: 1.01-1.03) and fasting blood glucose (OR 1.19; 95% CI: 1.05-1.35) were the independent risk factors for microalbuminuria.

CONCLUSIONS

Adults in the general population of Shandong Province have a moderate prevalence of microalbuminuria. Those with hypertension and diabetes are at high risk of having microalbuminuria, suggesting the need for screening and early intervention for microalbuminuria among these individuals.

Diabetic nephropathy: traditional to proteomic markers

Diabetic nephropathy (DN) is one of the major microvascular complications of diabetes and it is defined as a rise in the urinary albumin excretion (UAE) rate and abnormal renal function. Currently, changes in albuminuria are considered a hallmark of onset or progression of DN. However, some patients with diabetes have advanced renal pathological changes and progressive kidney function decline even if urinary albumin levels are in the normal range, indicating that albuminuria is not the perfect marker for the early detection of DN. The present article provides an overview of the literature reporting some relevant biomarkers that have been found to be associated with DN and that potentially may be used to predict the onset and/or monitor the progression of nephropathy. In particular, biomarkers of renal damage, inflammation, and oxidative stress may be useful tools for detection at an early stage or prediction of DN. Proteomic-based biomarker discovery represents a novel strategy to improve diagnosis, prognosis and treatment of DN; however, proteomics-based approaches are not yet available in most of the clinical chemistry laboratories. The use of a panel with a combination of biomarkers instead of urinary albumin alone seems to be an interesting approach for early detection of DN, including markers of glomerular damage (e.g., albumin), tubular damage (e.g., NAG and KIM-1), inflammation (e.g., TNF-α) and oxidative stress (e.g., 8-OHdG) because these mechanisms contribute to the development and outcomes of this disease.

The impact of renin-angiotensin-aldosterone system inhibitors on Type 1 and Type 2 diabetic patients with and without early diabetic nephropathy

Renin-angiotensin-aldosterone system inhibitors prevent the progression of kidney disease in patients with diabetic nephropathy, and we studied how that benefit varies by the type of diabetes and baseline urinary albumin. We pooled data from 49 randomized controlled trials in a meta-analysis using the ratio of endpoint urinary albumin levels in those treated compared to those untreated with renin-angiotensin-aldosterone system inhibitors in both fixed- and random-effects models. The urinary albumin excretion for treated microalbuminuric patients with Type 1 diabetes was on average 60% lower at the end of the trial compared with patients not treated with renin-angiotensin-aldosterone system inhibitors using the fixed-effects model and 67% lower using the random-effects model. There was no significant effect of treatment in patients with normal albumin excretion. For normoalbuminuric patients with Type 2 diabetes, urinary albumin excretion was on average 12% lower after treatment using the fixed-effects model compared to 21% lower using the random-effects model. For microalbuminuric patients, urinary albumin excretion was on average 23% lower using the fixed-effects model and 27% lower using the random-effects model. Thus, renin-angiotensin-aldosterone system inhibition reduced urinary albumin excretion for Type 1 diabetic patients with micro-, but not those with normoalbuminuria. Treatment reduced urinary albumin excretion for Type 2 diabetic patients with and without microalbuminuria.

Underestimation of urinary albumin to creatinine ratio in morbidly obese subjects due to high urinary creatinine excretion

BACKGROUND & AIMS

Albuminuria, a chronic kidney and/or cardiovascular disease biomarker, is currently measured as albumin-to-creatinine ratio (ACR). We hypothesize that in severely obese individuals ACR might be abnormally low in spite of relatively high levels of urinary albumin due to increased creatininuria.

METHODS

One-hundred-eighty-four subjects were divided into tertiles based on their BMI. Fat-free mass (FFM) and fat-mass were assessed by DEXA; 24-h creatinine and albumin excretion, ACR, lipid profile and blood pressure were measured.

RESULTS

Twenty-four-hour creatinine highly correlated (R = 0.75) with FFM. Since both creatininuria and albuminuria increased with the BMI, being the increase in creatininuria preponderant in subjects with BMI>35, their ratio (AC-ratio) did not change significantly from that of subjects in the lower BMI tertile. ACR only correlated with the systolic blood pressure, while both albuminuria and cretininuria correlated (P = 0.01) with the absolute 10-year CHD risk. In subjects with BMI>35, 100 mg of albumin excreted with urine increased the CHD risk of 2%.

CONCLUSIONS

Albumin-to-creatinine ratio is underestimated in severely obese individuals as a consequence of the large creatininuria, which is proportional to the increased FFM. Therefore, at least in this population 24-h albuminuria should be more reliable than ACR.

Higher estimated glomerular filtration rates may be associated with increased risk of adverse outcomes, especially with concomitant proteinuria

The estimated glomerular filtration rate (eGFR) is a powerful predictor of adverse outcomes, but most attention has focused on studies in the setting of reduced eGFR. Here we tested whether patients with an eGFR higher than 60-89.9 ml/min per 1.73 m(2) could also be at elevated risk of adverse outcomes. Further, we tested whether concomitant proteinuria further increases the risk of outcomes among individuals with an eGFR equal to or above 90 ml/min per 1.73 m(2), as it does for those with reduced eGFR. Using data from a population-based outpatient laboratory data set of 1,526,437 patients, we measured adjusted associations between eGFR calculated by the modification of diet in renal disease equation, urine dipstick proteinuria, and adverse clinical outcomes. The adjusted risk of all-cause mortality was lowest at an eGFR of 60-74.9 ml/min per 1.73 m(2) (referent) and increased at both lower and higher levels of eGFR. Specifically, the hazard ratio of death was 3.7 and 1.8 among patients with an eGFR equal to or above 105 and 90-104.9 ml/min per 1.73 m(2), respectively, compared to the referent group. Similar results were seen when the CKD-EPI equation (sensitivity analyses) was used to assess eGFR. Higher levels of eGFR were not associated with the risk of kidney failure or myocardial infarction. Thus, the presence and severity of proteinuria was significantly associated with graded increases in the risk of clinical outcomes for both lower and higher eGFR. We do not know, however, whether the finding at higher eGFR could be due to inadequacies of the eGFR formula at low serum creatinine levels.

Estimated glomerular filtration rate and its association with the retinol-binding protein 4 (RBP4) locus on human chromosome 10q23

BACKGROUND

We tested for associations between estimated glomerular filtration rate (eGFR) and retinol-binding protein 4 (RBP4) haplotypes found on human chromosome 10q23. This locus had been linked to eGFR in a previous linkage scan in patients with Type 2 diabetes mellitus.

METHODS

We analysed 469 patients with Type 2 diabetes and 174 normoalbuminuric controls for associations between RBP4 haplotypes and eGFR. For comparison with controls, 295 cases with proteinuria/end-stage renal disease were tested for associations with advanced diabetic nephropathy. Genotyping was performed using high-resolution DNA melting assays. Data analysis was performed using the haplo.stats package.

RESULTS

Genetic variations in RBP4 were not associated with advanced diabetic nephropathy. Compared with the common A/G/G/C haplotype, C/A/A/C carriers among the normoalbuminuric controls had higher eGFR values among younger patients but lower eGFRs among the older patients (effect size=2.2, P=3.3×10(-7)). Furthermore, while eGFR values were fairly consistent over the range of systolic blood pressure (SBP) values for the common haplotype, eGFR in C/A/A/C carriers increased with SBP (effect size=3.6, P=1.5×10(-2)). There was a significant interaction between the C/A/A/C haplotype and HbA1c as they affect eGFR compared to the common haplotype (effect size=2.1, P=2.1×10(-3)). Power calculations demonstrated that our study had >90% power to detect the observed interactions even while performing multiple hypotheses testing. The interaction between SBP and the C/A/A/C haplotype remained significant (P=2.8×10(-2)) even when these three haplotype-environment interactions were simultaneously estimated.

CONCLUSION

RBP4 haplotypes may be important in genetically modulating renal function in response to environmental challenges among patients with Type 2 diabetes.

A simple model for predicting incidence of chronic kidney disease in HIV-infected patients

BACKGROUND

Human immunodeficiency virus (HIV)-infected individuals have concurrent risk factors for chronic kidney disease (CKD), but there are no prediction models to quantify the effect of multiple factors on the development of incident CKD.

METHODS

A 1-year prognostic model was developed using prospective data between January 2008 and March 2009, from a derivation cohort of 623 patients with an estimated glomerular filtration rate (eGFR) exceeding 60 ml/min/1.73 m(2) at baseline. Incident CKD was defined as both an eGFR falling below 60 ml/min/1.73 m(2) and a decrease in eGFR of at least 25% during the period. Continuous variables were divided into categories using the mean value of the whole cohort. Multivariate logistic regression was used to determine baseline categories associated with incident CKD. The model was tested with prospective data between April 2009 and March 2010, from a validation cohort of 534 patients exceeding 60 ml/min/1.73 m(2) at baseline, consisting of part of the derivation cohort and newly enrolled patients. The discriminative ability was evaluated using the area under the receiver operating characteristic (AROC) curve.

RESULTS

Eighteen subjects developed incident CKD (2.9%). In a multivariate logistic regression analysis of the derivation cohort, 5 variables (age, CD4 cell count, diabetes, proteinuria, and eGFR at baseline) were independently associated with the incidence of CKD. The AROC curve was 0.841 (95% CI 0.799-0.894) in the validation cohort.

CONCLUSION

This prediction model may be a useful tool for identifying HIV-infected individuals with a high likelihood of new-onset CKD.

Proteinuria versus albuminuria in chronic kidney disease

Chronic kidney disease (CKD) is defined according to a decrease in the glomerular filtration rate and kidney damage such as proteinuria or albuminuria. Dip-stick proteinuria is only sensitive to albumin and correlates poorly with quantitative 24 h proteinuria, the most commonly used measure in renoprotective randomized controlled clinical trials (RCT). The amount of proteinuria correlates with the efficacy of angiotensin-converting enzyme inhibitors in non-diabetics in RCT. Random urine protein to creatinine ratio (PCR) or albumin to creatinine ratio (ACR) correlates with 24 h urinary excretion. Dip-stick proteinuria correlates poorly with ACR, while PCR correlates reasonably well with ACR. Because of a high analytical variability, efforts are in progress to standardize ACR (but not PCR) measurement. There have been no studies on the direct comparison between proteinuria and albuminuria in terms of utilities (biomarker, surrogate end-point and cost-effectiveness). In this regard, both proteinuria and albuminuria are good biomarkers for cardiovascular events, renal events or mortality. However, there are limitations in RCT regarding the validity of proteinuria or albuminuria as a surrogate end-point. In contrast, measuring proteinuria or albuminuria followed by treatment with angiotensin inhibitors is cost-effective for diabetics, hypertension and aging. CKD guidelines differ in their opinions regarding the choice between ACR and PCR. Based on the current evidence, ACR might be recommended for the diabetics and PCR for the non-diabetics.

Mistakes, misunderstandings and controversies in diabetes: A review and personal account

A number of controversies in diabetes have had too little attention. I discuss the following issues: (i) drug therapy; (ii) genetics; (iii) antihypertensive treatment in patients with normoalbuminuria and with abnormal albuminuria; (iv) insulin analogs; (v) cancer in diabetes; (vi) hypophysectomy; (vii) renal biopsy; (viii) low protein diet; and (ix) glycated hemoglobin. A closer look at these items is required in order to have a more realistic picture of diabetes research. A scheme of other controversies is also provided. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00012.x, 2010)