Metabolic and Hormonal Determinants of Glomerular Filtration Rate and Renal Hemodynamics in Severely Obese Individuals

Cortisol excess in chronic kidney disease - A review of changes and impact on mortality

Chronic kidney disease (CKD) describes the long-term condition of impaired kidney function from any cause. CKD is common and associated with a wide array of complications including higher mortality, cardiovascular disease, hypertension, insulin resistance, dyslipidemia, sarcopenia, osteoporosis, aberrant immune function, cognitive impairment, mood disturbances and poor sleep quality. Glucocorticoids are endogenous pleiotropic steroid hormones and their excess produces a pattern of morbidity that possesses considerable overlap with CKD. Circulating levels of cortisol, the major active glucocorticoid in humans, are determined by a complex interplay between several processes. The hypothalamic-pituitary-adrenal axis (HPA) regulates cortisol synthesis and release, 11β-hydroxysteroid dehydrogenase enzymes mediate metabolic interconversion between active and inactive forms, and clearance from the circulation depends on irreversible metabolic inactivation in the liver followed by urinary excretion. Chronic stress, inflammatory states and other aspects of CKD can disturb these processes, enhancing cortisol secretion via the HPA axis and inducing tissue-resident amplification of glucocorticoid signals. Progressive renal impairment can further impact on cortisol metabolism and urinary clearance of cortisol metabolites. Consequently, significant interest exists to precisely understand the dysregulation of cortisol in CKD and its significance for adverse clinical outcomes. In this review, we summarize the latest literature on alterations in endogenous glucocorticoid regulation in adults with CKD and evaluate the available evidence on cortisol as a mechanistic driver of excess mortality and morbidity. The emerging picture is one of subclinical hypercortisolism with blunted diurnal decline of cortisol levels, impaired negative feedback regulation and reduced cortisol clearance. An association between cortisol and adjusted all-cause mortality has been reported in observational studies for patients with end-stage renal failure, but further research is required to assess links between cortisol and clinical outcomes in CKD. We propose recommendations for future research, including therapeutic strategies that aim to reduce complications of CKD by correcting or reversing dysregulation of cortisol.

Prevalence of Drug Interaction in Severely Obese Individuals and Associated Factors: Baseline Results from a Clinical Trial

The prevalence of obesity is increasing worldwide and is commonly associated with comorbidities. The use of several drugs is often necessary, which leads to Potential Drug Interactions (PDI) that may increase the morbidity and mortality. This study aimed to analyze the prevalence of drug interaction and its association with socio-demographics, health status, and drug use in severely obese individuals. Baseline data from a randomized clinical trial registered at Clinicaltrial.gov (NCT02463435) were used. A total of 150 individuals aged 18–65 years with a body mass index of 35 kg/m2 were included. The outcome variable was the presence of PDI, and the explanatory variables were divided into the following four levels: socio-demographic, lifestyle, health, and medication use. The prevalence of PDI was 50% (n = 75) (95% CI 41–58). The variables associated with drug–drug interactions in the multiple analyses were arterial hypertension (PR 1.83, 95%, CI 1.10–3.04), polypharmacy (PR 3.12, 95%, CI 2.17–4.50), and diabetes mellitus (PR 0.60, 95%, CI 0.45–0.81). The risk factors for the occurrence of drug interaction were the presence of diabetes mellitus, hypertension, and polypharmacy.

[Changes in metabolic parameters and glomerular filtration rate in patients with morbid obesity after bariatric surgery]

AIM

To study the effect of weight loss in the short term after bariatric surgery (BO) on metabolic parameters and glomerular filtration rate (GFR) in patients with morbid obesity.

MATERIALS AND METHODS

We studied 40 adult (over 18 years) patients with morbid obesity who underwent bariatric surgery. Metabolic indices and calculated GFR according to the CKD-EPI formula in patients before and after bariatric surgery were compared.

RESULTS

In the whole group of operated patients, the average body mass index (BMI) after surgery decreased from 45.8 to 30.5 kg/m2. In 11 (92%) patients with impaired carbohydrate metabolism, remission of diabetes mellitus was achieved and sugar-lowering drugs were canceled. In patients with baseline GFR90 ml/min/1.73 m2 after surgery, there is a tendency towards a decrease in GFR, probably due to a decrease in hyperfiltration. In patients with baseline GFR90 ml/min/1.73 m2 after surgery, a statistically significant increase in the level of GFR was noted. The greater metabolic efficacy of combined operations (mini-gastric bypass, biliopancreatic diversion) in relation to the correction of carbohydrate and fat metabolism was revealed.

CONCLUSION

Obesity is a modifiable risk factor for decreased kidney function and the progression of chronic kidney disease. Bariatric surgery is an effective treatment for morbid obesity. The study proved the positive effect of weight loss after BO on renal function, including by improving the course of diseases associated with obesity.

The effect of body mass index and creatinine clearance on serum trough concentration of vancomycin in adult patients

Background

The aim of this study was to evaluate the influence of patient body mass index (BMI) and estimated creatinine clearance (CrCl) on serum vancomycin concentrations to define a possible optimal dosage regimen in overweight patients based on data obtained during therapeutic drug monitoring.

Methods

This retrospective study used data collected from January 2017 to January 2019. Adult patients (n = 204) received vancomycin treatment at a dose of 1000 mg every 12 h and underwent serum monitoring. Data collected included patient disease category, sex, age, height, weight, vancomycin concentrations, and serum creatinine. The CrCl values were estimated using the Cockcroft-Gault formula. In this study, statistical comparisons were performed on the results of patients according to serum vancomycin concentration.

Results

Serum vancomycin concentration was significantly related to BMI (P <  0.001) and CrCl (P <  0.05) in adult patients. Furthermore, the trough serum vancomycin concentration showed a logarithmic correlation with BMI (R = − 0.5108, 95% CI: − 0.6082 to − 0.3982, P <  0.001) and CrCl (R = − 0.5739, 95% CI: − 0.6616 to − 0.4707, P <  0.001). The multivariate analysis showed that BMI and CrCl are independent contributors to the trough vancomycin concentration. Moreover, some of the patients with higher BMI (≥ 24 kg/m²) met the goal trough concentration after an adjustment from 1000 mg every 12 h to 1000 mg every 8 h.

Conclusions

Serum vancomycin concentration decreases progressively with increasing BMI and the augmentation in CrCl in adult patients. The trough concentration of vancomycin should be continuously monitored for patients with a BMI ≥ 24 kg/m², and the dosage regimen should be adjusted to reach the target trough concentration in these patients to reduce the impact of BMI.

Estimated Glomerular Filtration Rate Bias in Participants with Severe Obesity Regardless of Deindexation

OBJECTIVE

Morbid obesity is associated with a higher independent risk of chronic kidney disease (CKD). Estimated glomerular filtration rate (eGFR) has been evaluated in a limited number of study participants with severe obesity.

METHODS

A total of 706 measured GFR (mGFR) results from 598 participants with obesity (BMI ≥ 35 kg/m² ) were retrospectively collected. The performance of the Modification of Diet in Renal Disease (MDRD) equation, Chronic Kidney Disease-Epidemiology (CKD-EPI) equation, and deindexed eGFR were compared with mGFR from the gold standard technique (inuline or iohexol), adjusted (mGFRr) or nonadjusted (mGFR) to body surface area. Absolute bias, precision, and accuracy were calculated.

RESULTS

Mean mGFRr (58 ± 31 mL/min/1.73 m² ) was significantly different from CKD-EPI and MDRD (P < 0.001). Mean mGFR (nonindexed) (70 ± 40 mL/min) was significantly higher than mGFRr (P < 0.001). eGFR showed important biases and low accuracies for CKD-EPI and MDRD (10.7 ± 10.7 and 12.2 ± 13.7 mL/min/1.73 m² ; 78% vs. 75% respectively). Deindexation worsened bias and accuracy 30% (percentage of GFR estimates within 30% of mGFRr or mGFR) between eGFR and mGFR.

CONCLUSIONS

eGFR overestimates mGFR and is associated with important biases and inaccuracies in patients with severe obesity, and deindexing eGFR worsens the overestimation. These findings may have important implications in examining kidney function in patients with obesity.

Relationship Between the Estimated Glomerular Filtration Rate and Visceral Fat Thickness Based on Ultrasound in Patients With Obesity Who Have Normal Renal Function Without Hypertension or Diabetes

OBJECTIVES

To investigate the relationship between visceral fat thickness measured by US and the estimated glomerular filtration rate (GFR) in patients with obesity who did not have hypertension or diabetes and who had normal renal function.

METHODS

Inclusion criteria included an estimated GFR of greater than 90 mL/min/1.73 m² , blood pressure lower than 120/80 mm Hg, and a fasting blood glucose level of less than 126 mg/dL. Patients were divided into groups with (body mass index ≥28 kg/m² ) and without (body mass index <28 kg/m² ) obesity. Subcutaneous and visceral fat thicknesses were measured with ultrasound.

RESULTS

A total of 95 patients were enrolled with an age range of 25 to 58 years. The patients were divided into groups with (n = 48) and without obesity (n = 47); patients with obesity were further divided into subcutaneous obesity (n = 23) and visceral obesity (n = 25) groups. The estimated GFR in the group with obesity was significantly lower than that in the group without obesity (P = .037), and the estimated GFR in the group with visceral obesity was significantly lower than that in the group with subcutaneous obesity (P = .006). Moreover, the estimated GFR was negatively correlated with visceral fat thickness (V1:r = -0.750;P7 < 0.001;V2:r = -0.824;P < 0.001) but not correlated with subcutaneous fat thickness.

CONCLUSIONS

Ultrasound is an easy and accurate practical evaluation modality for measuring the thickness of fat. There was an inverse relationship between the estimated GFR and visceral fat thickness in patients with obesity who did not have hypertension or diabetes and who had normal renal function. This result suggests that as visceral fat increases, the estimated GFR may be reduced accordingly.

Renal Resistive Index Predicts Post-Bariatric Surgery Renal Outcome in Nondiabetic Individuals with Severe Obesity

OBJECTIVE

Bariatric surgery may ameliorate renal function through vascular mechanisms. This study tested surgery's ability to improve measured glomerular filtration rate (mGFR) and identified clinical, renal, and systemic vascular predictors of such improvement.

METHODS

Twenty-five nondiabetic subjects with severe obesity were studied before and 1 year after Roux-en-Y gastric bypass, evaluating mGFR and renal plasma flow, basal renal resistive index (RI) and dynamic renal RI, renal visceral fat, and systemic vascular parameters, including flow-mediated dilation, aortic pulse wave velocity, and carotid intima media thickness and stiffness.

RESULTS

After Roux-en-Y gastric bypass, BMI decreased by 31%. At follow-up, body surface area (BSA)-adjusted mGFR increased (from 86.9 ± 15.2 to 109.0 ± 18.2 mL/min/1.73 m² , P <  0.001), whereas the absolute mGFR did not change. Renal plasma flow did not vary. RI decreased; flow-mediated dilation, pulse wave velocity, carotid intima media thickness, and carotid stiffness improved. mGFR changes after surgery (ΔmGFR/BSA) were associated with younger age and lower fasting glucose. Among vascular variables, an improved ΔmGFR/BSA was associated with smaller brachial artery diameter, lower intima media thickness, and lower RI; this latter association remained after adjusting for covariates. No measure of adiposity was associated with ΔmGFR.

CONCLUSIONS

In subjects with obesity and normal renal function, bariatric surgery improves mGFR/BSA (although absolute mGFR is unchanged) and renal and systemic vascular function. Lower renal intravascular resistance can predict these improvements, maximizing them in relatively young individuals.

Dapagliflozin acutely improves endothelial dysfunction, reduces aortic stiffness and renal resistive index in type 2 diabetic patients: a pilot study

Background

Sodium-glucose cotransporter-2 inhibitors reduce blood pressure (BP) and renal and cardiovascular events in patients with type 2 diabetes through not fully elucidated mechanisms. Aim of this study was to investigate whether dapagliflozin is able to acutely modify systemic and renal vascular function, as well as putative mechanisms.

Methods

Neuro-hormonal and vascular variables, together with 24 h diuresis, urinary sodium, glucose, isoprostanes and free-water clearance were assessed before and after a 2-day treatment with dapagliflozin 10 mg QD in sixteen type 2 diabetic patients; data were compared with those obtained in ten patients treated with hydrochlorothiazide 12.5 mg QD. Brachial artery endothelium-dependent and independent vasodilation (by flow-mediated dilation) and pulse wave velocity were assessed. Renal resistive index was obtained at rest and after glyceryl trinitrate administration. Differences were analysed by repeated measures ANOVA, considering treatment as between factor and time as within factor; Bonferroni post hoc comparison test was also used.

Results

Dapagliflozin decreased systolic BP and induced an increase in 24 h diuresis to a similar extent of hydrochlorothiazide; 24 h urinary glucose and serum magnesium were also increased. 24 h urinary sodium and fasting blood glucose were unchanged. Oxidative stress was reduced, as by a decline in urinary isoprostanes. Flow-mediated dilation was significantly increased (2.8 ± 2.2 to 4.0 ± 2.1%, p < 0.05), and pulse-wave-velocity was reduced (10.1 ± 1.6 to 8.9 ± 1.6 m/s, p < 0.05), even after correction for mean BP. Renal resistive index was reduced (0.62 ± 0.04 to 0.59 ± 0.05, p < 0.05). These vascular modifications were not observed in hydrochlorothiazide-treated individuals.

Conclusions

An acute treatment with dapagliflozin significantly improves systemic endothelial function, arterial stiffness and renal resistive index; this effect is independent of changes in BP and occurs in the presence of stable natriuresis, suggesting a fast, direct beneficial effect on the vasculature, possibly mediated by oxidative stress reduction.

Determinants of glomerular filtration rate following bariatric surgery in individuals with severe, otherwise uncomplicated, obesity: an observational, prospective study

AIMS

Obesity-induced nephropathy is an established clinical entity arising from a "maladaptive" response to lipid accumulation at the nephron level. Bariatric surgery positively affects renal function, reducing or increasing glomerular filtration rate (GFR) in subjects with hyperfiltration and renal impairment, respectively. The effect of this surgery in patients with normal estimated GFR (eGFR) is less clear.

METHODS

A complete clinical and biochemical assessment of 135 severely obese, otherwise healthy subjects, was obtained before Roux-en-Y gastric bypass (RYGB). All subjects underwent an OGTT with plasma glucose and insulin determinations. Follow-up data were recorded at 6, 12, 24 and 48 months after intervention.

RESULTS

Baseline eGFR was 98.2 ± 13.6 ml/min/1.73 m²; hyperfiltration (>120 ml/min/1.73 m²) was present in 7% of the cohort. No eGFR variation over the follow-up emerged, except at the last visit (-3.6 ± 1.4 ml/min/1.73 m² at month 48, p = 0.01 vs baseline). In the univariate analysis, the renal performance at 48 months was inversely related to baseline eGFR (r = -0.17, p = 0.04) and plasma triglycerides (r = -0.04, p = 0.05). Fasting and OGTT-derived variables did not impact eGFR. By multiple regression analysis, eGFR time course was independently predicted only by baseline eGFR (p = 0.03). Interestingly, patients having a baseline eGFR >100 ml/min/1.73 m² (median value) showed, after 48 months, an average loss of -8.3 ± 2.2 ml/min/1.73 m², while those with eGFR <100 exhibited a slight increase (+1.8 ± 2.3 ml/min/1.73 m², p < 0.01).

CONCLUSIONS

Long-term data confirm the safety of RYGB on renal function. Interestingly, a subtle hyperfiltration, i.e., occurring in high-normal range of eGFR, is attenuated by surgical procedure. Lastly, high serum triglycerides may track an unfavorable renal outcome.

PROBLEM OF THE ASSESMENT OF GLOMERULAR FILTRATION RATE IN OBESITY

The article discusses the problem of choosing an adequate method of assessing glomerular filtration rate in overweight and obesity.