Glomerular hemodynamics in severe obesity

Glomerular hyperfiltration

Circulating blood is filtered across the glomerular barrier to form an ultrafiltrate of plasma in the Bowman's space. The volume of glomerular filtration adjusted by time is defined as the glomerular filtration rate (GFR), and the total GFR is the sum of all single-nephron GFRs. Thus, when the single-nephron GFR is increased in the context of a normal number of functioning nephrons, single glomerular hyperfiltration results in 'absolute' hyperfiltration in the kidney. 'Absolute' hyperfiltration can occur in healthy people after high protein intake, during pregnancy and in patients with diabetes, obesity or autosomal-dominant polycystic kidney disease. When the number of functioning nephrons is reduced, single-nephron glomerular hyperfiltration can result in a GFR that is within or below the normal range. This 'relative' hyperfiltration can occur in patients with a congenitally reduced nephron number or with an acquired reduction in nephron mass consequent to surgery or kidney disease. Improved understanding of the mechanisms that underlie 'absolute' and 'relative' glomerular hyperfiltration in different clinical settings, and of whether and how the single-nephron haemodynamic and related biomechanical forces that underlie glomerular hyperfiltration promote glomerular injury, will pave the way toward the development of novel therapeutic interventions that attenuate glomerular hyperfiltration and potentially prevent or limit consequent progressive kidney injury and loss of function.

A Wide-Proteome Analysis to Identify Molecular Pathways Involved in Kidney Response to High-Fat Diet in Mice

The etiopathogenesis of obesity-related chronic kidney disease (CKD) is still scarcely understood. To this aim, we assessed the effect of high-fat diet (HF) on molecular pathways leading to organ damage, steatosis, and fibrosis. Six-week-old male C57BL/6N mice were fed HF diet or normal chow for 20 weeks. Kidneys were collected for genomic, proteomic, histological studies, and lipid quantification. The main findings were as follows: (1) HF diet activated specific pathways leading to fibrosis and increased fatty acid metabolism; (2) HF diet promoted a metabolic shift of lipid metabolism from peroxisomes to mitochondria; (3) no signs of lipid accumulation and/or fibrosis were observed, histologically; (4) the early signs of kidney damage seemed to be related to changes in membrane protein expression; (5) the proto-oncogene MYC was one of the upstream transcriptional regulators of changes occurring in protein expression. These results demonstrated the potential usefulness of specific selected molecules as early markers of renal injury in HF, while histomorphological changes become visible later in obesity-related CDK. The integration of these information with data from biological fluids could help the identification of biomarkers useful for the early detection and prevention of tissue damage in clinical practice.

Glomerular resistances predict long-term GFR decline in type 2 diabetic patients without overt nephropathy: a longitudinal subgroup analysis of the DEMAND trial

AIMS

Investigating whether and to what extent changes in glomerular hemodynamic parameters, beyond glomerular hyperfiltration, could predict glomerular filtration rate (GFR) decline in hypertensive, non-proteinuric type 2 diabetic patients.

MATERIALS AND METHODS

We estimated baseline afferent (Ra) and efferent (Re) arteriolar resistances and glomerular hydrostatic pressure in 60 consecutive patients from DEMAND study, using the Gomez' equations. Baseline renal plasma flow was measured by para-aminohippurate plasma clearance, and GFR was measured by iohexol plasma clearance at baseline and every 6 months for a median of 4.0 years [IQR 3.5-4.0 years]. Patients with a GFR decline > or ≤ 3 mL/min/1.73 m²/year were categorized as "Progressors" and "Non-progressors," respectively. Predictors of GFR decline were studied by univariable and multivariable logistic regression analysis.

RESULTS

•The GFR declined by a median [IQR] of 4.06 [5.46-2.00] mL/min/1.73 m²/year in the study group as a whole and by 5.35 [6.60-4.48] mL/min/1.73 m²/year and 1.71 [2.14-1.33] mL/min/1.73 m²/year in Progressors and Non-progressors, considered separately. Progressors had a higher baseline Ra (3487.3 ± 1349.3 dyne•sec•cm^-5 vs. 2877.0 ± 668.9 dyne•sec•cm^-5, p < 0.05) and higher Ra/Re ratio (1.4 ± 0.5 vs. 1.1 ± 0.3, p < 0.01) than Non-progressors. At multivariable logistic regression analysis, Ra/Re ratio and arterial hypertension duration were independently associated with GFR decline (odds ratio [95% CI] 8.50 [1.56-46.28] and 1.14 [1.01-1.28]), respectively.

CONCLUSIONS

Increased Ra/Re ratio and arterial hypertension duration predict early GFR decline in hypertensive non-proteinuric type 2 diabetic patients. These findings could be explained by glomerular hypoperfusion and chronic ischemic injury related to pre-glomerular arteriolar narrowing.

CLINICAL TRIAL REGISTRATION

DEMAND, NCT00157586, September 12, 2005.

Glomerular Biomechanical Stress and Lipid Mediators during Cellular Changes Leading to Chronic Kidney Disease

Hyperfiltration is an important underlying cause of glomerular dysfunction associated with several systemic and intrinsic glomerular conditions leading to chronic kidney disease (CKD). These include obesity, diabetes, hypertension, focal segmental glomerulosclerosis (FSGS), congenital abnormalities and reduced renal mass (low nephron number). Hyperfiltration-associated biomechanical forces directly impact the cell membrane, generating tensile and fluid flow shear stresses in multiple segments of the nephron. Ongoing research suggests these biomechanical forces as the initial mediators of hyperfiltration-induced deterioration of podocyte structure and function leading to their detachment and irreplaceable loss from the glomerular filtration barrier. Membrane lipid-derived polyunsaturated fatty acids (PUFA) and their metabolites are potent transducers of biomechanical stress from the cell surface to intracellular compartments. Omega-6 and ω-3 long-chain PUFA from membrane phospholipids generate many versatile and autacoid oxylipins that modulate pro-inflammatory as well as anti-inflammatory autocrine and paracrine signaling. We advance the idea that lipid signaling molecules, related enzymes, metabolites and receptors are not just mediators of cellular stress but also potential targets for developing novel interventions. With the growing emphasis on lifestyle changes for wellness, dietary fatty acids are potential adjunct-therapeutics to minimize/treat hyperfiltration-induced progressive glomerular damage and CKD.

Effects of hyperuricaemia, with the superposition of being overweight and hyperlipidaemia, on the incidence of acute kidney injury following cardiac surgery: a retrospective cohort study

OBJECTIVES

Acute kidney injury (AKI) is a common complication of cardiac surgery. This study aimed to explore the effects of hyperuricaemia, being overweight and hyperlipidaemia as risk factors for AKI in patients following cardiac surgery (cardiac surgery-associated acute kidney injury (CSA-AKI)).

DESIGN

Retrospective observational study.

SETTING

University teaching, grade-A tertiary hospital in Shanghai, China.

PARTICIPANTS

Patients who underwent cardiac surgery from July 2015 to December 2015 in Zhongshan Hospital, Fudan University.

MAIN OUTCOME MEASURES

We investigated the effect of hyperuricaemia, in combination with being overweight and hyperlipidaemia, on the risk of CSA-AKI.

RESULTS

A total of 1420 patients were enrolled. The AKI incidence in the highest uric acid group was 44.4%, while that in the lowest uric acid group was 28.5% (p<0.001). Patients in the higher uric acid quartiles were more likely to be overweight and hyperlipidaemic at the same time (p<0.001). Multivariate logistic regression analysis showed that hyperuricaemia was an independent risk factor for AKI (OR=1.237, 95% CI 1.095 to 1.885; p=0.009); being overweight or hyperlipidaemia alone was not an independent risk factor, but the combination of being overweight and hyperlipidaemia was (OR=1.544, 95% CI 1.059 to 2.252; p=0.024). In the final model, the OR value increased to 3.126 when hyperuricaemia was combined with being overweight and hyperlipidaemia, and the Hosmer-Lemeshow test showed that all three models fit well (p=0.433, 0.638 and 0.597, respectively).

CONCLUSIONS

The combination of being overweight and having hyperlipidaemia was an independent risk factor, but being overweight or having hyperlipidaemia alone was not. The combination of hyperuricaemia, being overweight and hyperlipidaemia further increased the risk of CSA-AKI.

Treatment With Lisinopril Prevents the Early Progression of Glomerular Injury in Obese Dahl Salt-Sensitive Rats Independent of Lowering Arterial Pressure

Recently, we reported that obese Dahl salt-sensitive leptin receptor mutant (SSLepRmutant) rats develop glomerular injury and progressive proteinuria prior to puberty. Moreover, this early progression of proteinuria was associated with elevations in GFR. Therefore, the current study examined whether treatment with lisinopril to reduce GFR slows the early progression of proteinuria in SSLepRmutant rats prior to puberty. Experiments were performed on 4-week-old SS and SSLepRmutant rats that were either treated with vehicle or lisinopril (20 mg/kg/day, drinking water) for 4 weeks. We did not observe any differences in MAP between SS and SSLepRmutant rats treated with vehicle (148 ± 5 vs. 163 ± 6 mmHg, respectively). Interestingly, chronic treatment with lisinopril markedly reduced MAP in SS rats (111 ± 3 mmHg) but had no effect on MAP in SSLepRmutant rats (155 ± 4 mmHg). Treatment with lisinopril significantly reduced proteinuria in SS and SSLepRmutant rats compared to their vehicle counterparts (19 ± 5 and 258 ± 34 vs. 71 ± 12 and 498 ± 66 mg/day, respectively). Additionally, nephrin excretion was significantly elevated in SSLepRmutant rats versus SS rats, and lisinopril reduced nephrin excretion in both strains. GFR was significantly elevated in SSLepRmutant rats compared to SS rats, and lisinopril treatment reduced GFR in SSLepRmutant rats by 30%. The kidneys from SSLepRmutant rats displayed glomerular injury with increased mesangial expansion and renal inflammation versus SS rats. Chronic treatment with lisinopril significantly decreased glomerular injury and renal inflammation in the SSLepRmutant rats. Overall, these data indicate that inhibiting renal hyperfiltration associated with obesity is beneficial in slowing the early development of glomerular injury and renal inflammation.

The effect of body mass index on the development of acute kidney injury and mortality in intensive care unit: is obesity paradox valid?

BACKGROUND

The conflicting results of studies on intensive care unit (ICU) mortality of obese patients and obese patients with acute kidney injury (AKI) reveal a paradox within a paradox. The aim of this study was to determine the effects of body mass index and obesity on AKI development and ICU mortality.

METHODS

The 4,459 patients treated between January 2015 and December 2019 in the ICU at a Tertiary Care Center in Turkey were analyzed retrospectively.

RESULTS

AKI developed more in obese patients with 69.8% (620). AKI development rates were similar in normal-weight (65.1%; 1172) and overweight patients (64.9%; 1149). The development of AKI in patients who presented with cerebrovascular diseases was higher in obese patients (81; 76.4%) than in normal-weight (158; 62.7%) and overweight (174; 60.8%) patients (p < 0.05). The risk of developing AKI was approximately 1.4 times (CI 95% = 1.177-1.662) higher in obese patients than in normal-weight patients. Dialysis was used more frequently in obese patients (24.3%, p < 0.001), who stayed longer in the ICU (p < 0.05). It was determined that the development of AKI in normal-weight and overweight patients increased mortality (p < 0.001) and that there was not a difference in mortality rates between obese patients with and without AKI.

CONCLUSION

The risk of AKI development was higher in obese patients but not in those who were in serious conditions. Another paradox was that the development of AKI was associated with a higher mortality rate in normal-weight and overweight patients, but not in obese patients. Cerebrovascular diseases as a cause of admission pose additional risks for AKI.

Association between Body Mass Index and Chronic Kidney Disease in Asian Populations: A Participant-level Meta-Analysis

Obesity and chronic kidney disease (CKD) are major public health problems worldwide. However, the association between body mass index (BMI) and CKD is inconclusive in Asians. In this meta-analysis, eight population-based studies, from China, India, Russia (Asian), Singapore and South Korea, provided individual-level data (n=50037). CKD was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m². BMI was analyzed both as a continuous variable and in three categories: <25kg/m², normal; 25-29.9kg/m², overweight; and ≥30kg/m², obese. The association between BMI and CKD was evaluated in each study using multivariable logistic regression models and individual estimates were pooled using random-effect meta-analysis to obtain the pooled odds ratio (OR) and 95% confidence interval (CI). Associations were also evaluated in subgroups of age, gender, smoking, diabetes, and hypertension status. Of 50037 adults, 4258 (8.5%) had CKD. 13328 (26.6%) individuals were overweight while 4440 (8.9%) were obese. The prevalence of any CKD ranged from 3.5% to 29.1% across studies. In pooled analysis, both overweight and obesity were associated with increased odds of CKD, with pooled OR (95% CI) of 1.15 (1.03-1.29) and 1.23 (1.06-1.42), respectively. In subgroup analyses, significant associations between BMI and CKD were observed in adult males, non-smokers, and those with diabetes and arterial hypertension (all p<0.05). When evaluated as a continuous variable, BMI was not significantly associated with CKD. If confirmed in longitudinal studies, these results may have clinical implications in risk stratification and preventive measures, given that obesity and CKD are two major chronic diseases with substantial public health burden worldwide.

Relation of glomerular filtration to insulin resistance and related risk factors in obese children

BACKGROUND AND OBJECTIVE

Childhood obesity is associated with later development of significant renal morbidity. We evaluated the impact of the degree of insulin sensitivity on estimated glomerular filtration rate (eGFR) and determined the factors associated with eGFR in obese children. We further tested the relation of eGFR to clinical outcomes such as blood pressure and microalbuminuria.

MATERIALS AND METHODS

We evaluated the relation of whole body insulin sensitivity and estimated glomerular filtration rate (eGFR) across the spectrum of obesity in children and adolescents. eGFR was calculated using the iCARE formula, which has been validated in obese children with varying glucose tolerance.

RESULTS

1080 children and adolescents with overweight and obesity (701 females and 379 males) participated. Insulin sensitivity was a strongly negatively associated with (B = -2.72, p < 0.001) eGFR), even after adjustment for potential confounders. Male sex emerged to be significantly associated with eGFR with boys having greater values than girls (B = 18.82, p < 0.001). Age was a positively associated (B = 2.86, p < 0.001) with eGFR. Whole body and hepatic insulin sensitivity decreased across eGFR quartiles. Adjusted eGFR was tightly positively associated with systolic blood pressure (B = 0.09, p = 0.003) and negatively associated with the presence of microalbuminuria (B = -2.18, p = 0.04).

CONCLUSIONS

eGFR tends to increase with greater degrees of insulin resistance in children and adolescents representing hyperfiltration and is associated with cardiovascular risk factors. Longitudinal studies are needed to determine the natural history of childhood insulin resistance related hyperfiltration in regards to future kidney disease.

Obesity-Related Glomerulopathy: Clinical Management

Obesity-related glomerulopathy (ORG) and other obesity-associated kidney diseases pose a major challenge to the treating nephrologist. We review the benefits of weight loss and optimal management of ORG and kidney disease in the setting of obesity. Therapeutic strategies in ORG were limited mainly in the past to weight loss through lifestyle interventions and bariatric surgery, antihypertensive treatment, and renin-angiotensin-aldosterone system blockade. Current approaches to obtain the desired weight loss include novel pharmacologic therapies that have been approved for the treatment of diabetes while offering kidney protection, such as sodium-glucose cotransporter-2 inhibitors and glucagon-like peptide-1-receptor agonists. This review focuses on the nephroprotective role of the renin-angiotensin-aldosterone system blockade and of these new pharmacologic agents, and on the renal effects of bariatric surgery in chronic kidney disease.

Podocytopathy in Obesity: Challenges of Living Large

Renal injury resulting from obesity is a growing concern caused by the global obesity epidemic. We discuss the glomerular structure, obesity-related glomerular changes, and diagnostic pathologic criteria for obesity-related glomerulopathy. The three main hypothesized mechanisms of podocyte injury are mechanical stress on the podocytes, metabolic derangement, and genetic/molecular factors. Weight loss, renin-angiotensin-aldosterone system inhibitors, and improved insulin resistance may slow the progression. A more comprehensive understanding of obesity-related glomerulopathy will help in developing more effective therapies.

The Renal Pathology of Obesity: Structure-Function Correlations

The kidney is one of the target organs that may show health disorders as a result of obesity. Obesity-related glomerulopathy (ORG) is a kidney disease category based on a biopsy diagnosis that may occur secondary to obesity. Detailed clinicopathologic observations of ORG have provided significant knowledge regarding obesity-associated renal complications. Glomerulomegaly with focal segmental glomerulosclerosis of perihilar locations is a typical renal histopathologic finding in ORG, which has long been considered to represent a state of single-nephron glomerular hyperfiltration. This hypothesis was recently confirmed in ORG patients by estimating single-nephron glomerular filtration rate using a combined image analysis and biopsy-based stereology. Overshooting in glomerulotubular and tubuloglomerular interactions may lead to glomerular hyperfiltration/hypertension, podocyte failure, tubular protein-traffic overload, and tubulointerstitial scarring, constituting a vicious cycle of a common pathway to the further loss of functioning nephrons and the progression of kidney functional impairment.

Obesity-Related Glomerulopathy: From Mechanism to Therapeutic Target

Obesity-related glomerulopathy (ORG) is a secondary glomerular disease caused by obesity, with clinical manifestations such as proteinuria and glomerulomegaly. Currently, the high incidence of obesity brings a change in the spectrum of kidney diseases across the globe, including China. ORG has become another important secondary nephropathy leading to end-stage renal disease (ESRD), and its incidence has increased significantly. This trend is bound to bring about a serious socioeconomic burden. Therefore, it is urgent to study its pathogenesis and intervention measures. Currently, the occurrence and development mechanisms in ORG are complicated by many factors, which are still unclear. In the past 20 years, with the continuous intensive research on mechanisms such as hypoxia in the metabolic process, immune inflammation, and pyroptosis, there have been new advances in the mechanism of ORG, especially the important role of inflammation in podocyte injury and its impact on the progress of ORG. Here, we briefly review the possible pathogenic role of the inflammasome in the podocyte damage in ORG and summarize the possible therapeutical strategies targeting inflammasome.

Bariatric Surgery Improves Renal Function in Patients With Obesity

Background

Obesity affects 93.3 million adults in the United States and is a predisposing factor for the development and progression of chronic kidney disease (CKD). The objective of this study is to examine the association between weight loss and renal function in participants undergoing bariatric surgery following a 12-week multidisciplinary, community-based weight loss program.

Methodology

This is a retrospective chart review of participants who voluntarily enrolled in a 12-week multidisciplinary weight loss program prior to bariatric surgery from 2009 to 2018. The primary outcome was to assess the association between weight loss and renal function in participants undergoing bariatric surgery. Secondary outcomes included changes in hemoglobin A1c, lipids, fasting glucose, and blood pressure.

Results

Among the 55 participants, baseline glomerular filtration rate (GFR) was 49 mL/min/m², 80% were female, and the average baseline weight was 131 kg. At one-year post-intervention, 69% of patients improved in the CKD stage, with 45% of the participants improving from stage 3A to stage 2. GFR improved to 15 mL/min/1.73m² (p = 0.025), and there was a negative correlation (r_s = -0.3556) between weight and GFR (p = 0.013). Participants with hyperlipidemia had a 12 mL/min/1.73m² rise in GFR, while participants without the diagnosis at one year had a 24 mL/min/1.73m² rise in GFR (p = 0.007).

Conclusions

This study demonstrated improved renal function and reduced progression of CKD following a combined lifestyle and surgical intervention, indicating the importance of a comprehensive approach for the management of the chronic disease.

Direct Oral Anticoagulants in Patients with Obesity and Atrial Fibrillation: Position Paper of Italian National Association of Hospital Cardiologists (ANMCO)

The use of the direct oral anticoagulants dabigatran, rivaroxaban, apixaban and edoxaban (DOACs) offers some major advantages over warfarin and other vitamin K antagonists (VKAs). One advantage is the possibility to use a fixed dose in normal-weight patients, overweight patients and patients with obesity. However, the "one size fits all" strategy raised a concern regarding the possibility to undertreat patients with a high body mass index. No randomized controlled trials (RCTs) have ever compared VKAs and DOACs in this population. We analyzed data from the literature on DOAC pharmacokinetics and pharmacodynamics, results from the four pivotal phase III trials on non-valvular atrial fibrillation, retrospective observational studies and metanalyses. While we are aware of the limitation imposed by the absence of specific RCTs, we propose the position of the Italian Association of Hospital Cardiologists (ANMCO) on the use of DOACs in patients with obesity based on the existing evidence.

Longitudinal study of glomerular hyperfiltration and normalization of estimated glomerular filtration in adults with sickle cell disease

Glomerular hyperfiltration is common in sickle cell disease (SCD) and precedes proteinuria and declining kidney function. We evaluated hyperfiltration in SCD patients and its "normalization." Routine visit data were collected retrospectively from adult SCD patients in a single centre from 2004 to 2013. Baseline was defined as first available serum creatinine and hyperfiltration as estimated glomerular filtration rates (eGFR) >130 ml/min/1·73 m² for women and >140 ml/min/1·73 m² for men. Normalization of hyperfiltration was eGFR reduction to 90-130 ml/min/1·73 m² for women or 90-140 ml/min/1·73 m² for men. Among 292 patients, median age was 27 years [interquartile range (IQR):20·0-38·0], and 56·8% had baseline hyperfiltration. Baseline hyperfiltration was inversely associated with age [odds ratio (OR):0·86, 95% confidence interval (CI): 0·82-0·90; P < 0·0001], male sex (OR:0·16, 95% CI: 0·07-0·41; P = 0·0001), haemoglobin (OR:0·76, 95% CI 0·61-0·94; P = 0·01), weight (OR:0·96, 95% CI: 0·93-0·99; P = 0·004), and angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (ACE-I/ARB) use (OR:0·08, 95% CI: 0·01-0·75; P = 0·03), and positively with hydroxycarbamide use (OR:2·99, 95% CI: 1·18-7·56; P = 0·02). Of 89 hyperfiltration patients without baseline proteinuria, 10 (11·2%) developed new-onset proteinuria [median 1·05 years (IQR:0·63-2·09)]. Normalization of hyperfiltration was less likely with higher baseline eGFR [hazard ratio (HR):0·90, 95% CI: 0·86-0·95; P < 0·0001] and more likely in males (HR:6·35, 95% CI:2·71-14·86, <0·0001). Hyperfiltration is common in adult SCD patients, particularly when younger. Decline to normal values is more likely in males, possibly representing kidney function loss rather than improvement in hyperfiltration.

Pharmacokinetics of Direct Oral Anticoagulants in Patients With Atrial Fibrillation and Extreme Obesity

PURPOSE

Direct oral anticoagulants (DOACs) are recommended in preference to vitamin K antagonists (VKAs) for stroke prevention in patients with atrial fibrillation (AF) eligible for oral anticoagulation therapy; however, data and clinical experiences supporting the use of DOACs in patients with a body mass index ≥40 kg/m² or weight >120 kg remain limited. The aim of this study was to evaluate the pharmacokinetic properties of DOACs in patients with AF and extreme obesity.

METHODS

We enrolled all consecutive patients with AF and extreme obesity undergoing treatment with DOACs followed up at Monaldi Hospital, Naples, Italy. To determine peak plasma and trough levels of DOACs, plasma samples were collected at 2nd, 4th, 6th, and 12th hours from the last dose intake in patients receiving apixaban and dabigatran and at the 2nd, 4th, 6th, and 24th hours in those receiving edoxaban and rivaroxaban. The DOACs' peak and trough plasma levels obtained from our study population were compared with those sourced from pharmacokinetic studies among patients without obesity, defined as a normal reference range in the literature. If at least 1 peak or trough plasma level was found ​​below or above the normal reference ranges, the patients were classified as having out-of-range DOAC plasma levels. Study population was then divided into in-range and out-of-range groups. Baseline characteristics, including DOAC treatment, were compared between the 2 groups. Univariate and multivariate logistic regression analysis were performed to identify baseline variables associated with DOACs' plasma concentration out of the expected range.

FINDINGS

A total of 58 patients (mean [SD] age, 70.93 [8.73] years; 40% female) with extreme obesity (mean [SD] body mass index. 44.43 [3.54] kg/m²) and AF while undergoing DOAC treatment were included in the present study. In 9 patients (15.5 %), the DOAC plasma concentrations were out of the expected ranges (out-of-range group);, indicating a greater likelihood of edoxaban 30 mg treatment (33% vs 2%; P < 0.01) and inappropriate DOAC underdosing (56% vs 4%; P < 0.005) compared with the in-range group. According to the multivariate logistic analysis (P = 0.0011), the inappropriate DOAC underdosing (hazard ratio = 29.37; P = 0.0002) was an independent predictor of DOAC plasma levels out of the expected ranges.

IMPLICATIONS

Patients with extreme obesity and AF who were receiving DOAC therapy had DOAC plasma concentrations in the expected range. The inappropriate DOAC underdosing seems to be the only independent clinical factor associated with a plasma concentration of the drug out of the expected range.

Causal linkage between adult height and kidney function: An integrated population-scale observational analysis and Mendelian randomization study

As adult height is linked to various health outcomes, further investigation of its causal effects on kidney function later in life is warranted. This study involved a cross-sectional observational analysis and summary-level Mendelian randomization (MR) analysis. First, the observational association between height and estimated GFR determined by creatinine (eGFRcreatinine) or cystatin C (eGFRcystatinC) was investigated in 467,182 individuals aged 40-69 using UK Biobank. Second, the genetic instrument for adult height, as reported by the GIANT consortium, was implemented, and summary-level MR of eGFRcreatinine and CKDcreatinine in a CKDGen genome-wide association study was performed (N = 567,460), with multivariable MR being adjusted for the effects of genetic predisposition on body mass index. To replicate the findings, additional two-sample MR using the summary statistics of eGFRcystatinC and CKDcystatinC in UK Biobank was performed (N = 321,405). In observational analysis, adult height was inversely associated with both eGFRcreatinine (per 1 SD, adjusted beta -1.039, standard error 0.129, P < 0.001) and eGFRcystatinC (adjusted beta -1.769, standard error 0.161, P < 0.001) in a multivariable model adjusted for clinicodemographic, anthropometric, metabolic, and social factors. Moreover, multivariable summary-level MR showed that a taller genetically predicted adult height was causally linked to a lower log-eGFRcreatinine (adjusted beta -0.007, standard error 0.001, P < 0.001) and a higher risk of CKDcreatinine (adjusted beta 0.083, standard error 0.019, P < 0.001). Other pleiotropy-robust sensitivity MR analysis results supported the findings. In addition, similar results were obtained by two-sample MR of eGFRcystatinC (adjusted beta -1.303, standard error 0.140, P < 0.001) and CKDcystatinC (adjusted beta 0.153, standard error 0.025, P < 0.001) in UK Biobank. In conclusion, the results of this study suggest that a taller adult height is causally linked to worse kidney function in middle-aged to elderly individuals, independent of the effect of body mass index.

New Pandemic: Obesity and Associated Nephropathy

Incidence of obesity related renal disorders have increased 10-folds in recent years. One of the consequences of obesity is an increased glomerular filtration rate (GFR) that leads to the enlargement of the renal glomerulus, i.e., glomerulomegaly. This heightened hyper-filtration in the setting of type 2 diabetes irreparably damages the kidney and leads to progression of end stage renal disease (ESRD). The patients suffering from type 2 diabetes have progressive proteinuria, and eventually one third of them develop chronic kidney disease (CKD) and ESRD. For ameliorating the progression of CKD, inhibitors of renin angiotensin aldosterone system (RAAS) seemed to be effective, but on a short-term basis only. Long term and stable treatment strategies like weight loss via restricted or hypo-caloric diet or bariatric surgery have yielded better promising results in terms of amelioration of proteinuria and maintenance of normal GFR. Body mass index (BMI) is considered as a traditional marker for the onset of obesity, but apparently, it is not a reliable indicator, and thus there is a need for more precise evaluation of regional fat distribution and amount of muscle mass. With respect to the pathogenesis, recent investigations have suggested perturbation in fatty acid and cholesterol metabolism as the critical mediators in ectopic renal lipid accumulation associated with inflammation, increased generation of ROS, RAAS activation and consequential tubulo-interstitial injury. This review summarizes the renewed approaches for the obesity assessment and evaluation of the pathogenesis of CKD, altered renal hemodynamics and potential therapeutic targets.

Acute Kidney Injury in Cardiac Surgery Patients: Role of Glomerular Filtration Rate and Fat-Free Mass

Summary. Background.

eGFR (estimated glomerular filtration rate) formulas may be inaccurate in overweight cardiac surgery patients, overestimating the kidney reserve. The aim of this study was to modify the eGFR formulas and to determine whether the modified eGFR is a more accurate predictor of acute kidney injury (AKI).

Materials and methods

The patients were assigned into 4 BMI groups as follows: normal weight (18.5– 25 kg/m²), pre-obesity (25–30 kg/m²), class I obese (30–35 kg/m²), class II and III obese (≥35 kg/m²). Cockcroft– Gault (CG) eGFR formula was modified by using the fat-free mass (FFM) derived from bioelectrical impedance. ROC-AUC curves were analyzed to identify the accuracy of the eGFR formulas (CG, CG modified with FFM, Mayo Clinic Quadratic equation, CKD-EPI, MDRD) to predict the AKI in each group.

Results

Although all of the used equations showed similar predictive power in the normal weight and overweight category, Mayo formula had the highest AUC in predicting the occurrence of AKI (ROC-AUC 0.717 and 0.624, p<0.05). However, in the group of patients with class I obesity, only the CG formula modified with a fat-free mass appeared to be predictive of postoperative AKI (ROC-AUC 0.631 p<0.05). None of the equations were accurate in the group of BMI (>35 kg/m²).

Conclusions

eGFR is a poor predictor of AKI, especially in the obese patients undergoing cardiac surgery. The only equation with a moderate predictive power for the class I obese patients was the CG formula modified with the fat-free mass.

Non-Alcoholic Fatty Liver Disease Is Associated with Kidney Glomerular Hyperfiltration in Adults with Metabolic Syndrome

Background: Non-alcoholic fatty liver disease (NAFLD) is a risk factor for the development of chronic kidney disease (CKD), which is early marked by kidney glomerular hyperfiltration. However, the association of NAFLD with kidney glomerular hyperfiltration has not been tested so far in adults with metabolic syndrome (MetS). Aims: To assess the relationship between NAFLD and kidney glomerular hyperfiltration in adults with MetS. Methods: The study included 154 participants aged 40–60 years with MetS and NAFLD diagnosed by ultrasound. NAFLD was confirmed by MRI in 109 subjects. Participants underwent anthropometric measurements, and biochemistry testing. Estimated GFR (eGFR) was calculated using the CKD-Epidemiology Collaboration (CKD-EPI) formula; hyperfiltration was defined as eGFR ≥ 120 mL/min. Results: Participants with MRI-proven NAFLD showed a worse metabolic profile and higher levels of eGFR than those with no NAFLD. Presence of NAFLD and increased weight were independently associated with an increased probability of presenting hyperfiltration. Conclusions: The present study shows an association between kidney glomerular hyperfiltration and NAFLD in adults with MetS. Establishing an association between NAFLD and kidney glomerular hyperfiltration would help to earlier identify those patients at increased risk of CKD, who would benefit from an early intervention.

Effect of Bariatric Surgery on Diagnosed Chronic Kidney Disease and Cardiovascular Events in Patients with Insulin-treated Type 2 Diabetes: a Retrospective Cohort Study from a Large UK Primary Care Database

Aims

To compare the effect of bariatric surgery on renal, chronic kidney disease (CKD) and cardiovascular (CV) outcomes among obese patients with insulin-treated type 2 diabetes (T2D) with and without microalbuminuria (i.e., uACR > 3.0 mg/mmol).

Methods

A retrospective cohort study was conducted among 11,125 active patients with T2D from The Health Improvement Network (THIN) database. Propensity score matching (up to 1:6 ratio) was used to identify patients who underwent bariatric surgery (N = 131) with a non-bariatric cohort (N = 579). Follow-up was undertaken for 10 years (6487 person-years) to compare differences in risk of cardiovascular events and in renal outcomes.

Results

For the matched cohort at baseline: mean age 52 ± 13 years (60% female); weight 116 ± 25 kg, body mass index (BMI) 41 ± 9kg/m², estimated glomerular filtration rate (eGFR); 70.4 ± 20 mL/min/1.73 m², and median albumin-creatinine ratio (uACR) 2.0 mg/mmol (interquartile range (IQR): 0.9–5.2 mg/mmol). Bariatric surgery was associated with a 54% reduction in developing CKD compared to their matched non-bariatric cohort (adjusted hazard ratio [aHR]: 0.46; 95%CI: 0.24–0.85, P = 0.02). Among patients with microalbuminuria at baseline, bariatric surgery was protective against CKD (aHR: 0.42, 95%CI: 0.18–0.99, P = 0.050). eGFR was significantly increased from baseline favouring the bariatric group during 75% of the follow-up time (calculated mean difference between groups: 4.1 mL/min/1.73 m²; P < 0.05), especially at 5-year point (74.2 vs 67.8 mL/min/1.73 m²; P < 0.001). However, no significant change was observed with non-fatal CVD episodes (aHR: 0.36, 95%CI: 0.11–1.13, P = 0.079). Albumin levels were significantly reduced throughout the 2 years following the surgery (3.9 vs 4.1 g/dL, P < 0.001). uACR and total protein levels had little or no statistical association to the intervention.

Conclusion

Bariatric surgery may protect patients with diabetes with or without microalbuminuria against the risk of CKD and with a modest protective effect on non-fatal CVD risk. Bariatric surgery is also associated with improvements in overall renal outcomes such as eGFR.

Association of Serum Zinc Concentration with Preservation of Renal Function After Bariatric Surgery: a Retrospective Pilot Study

BACKGROUND

Although serum zinc level (Zn) is known to impact renal function in patients with diabetes, their correlation following bariatric surgery remains unknown. This study aimed at assessing the association of Zn with estimated glomerular filtration rate (eGFR) after laparoscopic sleeve gastrectomy (LSG).

METHODS

One hundred and twenty-nine patients in total (mean age, 38.1 ± 10.8; body mass index, 39.1 ± 5.1 kg/m²) with normal preoperative kidney function undergoing LSG at a single tertiary referral center were reviewed. The primary study endpoint was the relationship between Zn and post-LSG eGFR at 12-month follow-up. The secondary outcomes were the associations of percentage weight loss (%WL) with changes in Zn (△Zn) and eGFR (△eGFR).

RESULTS

The incidence of zinc deficiency was 8.5%, 8.1%, and 29.9% at baseline, post-LSG and one- and 12-month follow-up, respectively. At 12-month follow-up, Zn dropped from 104.1 ± 19.2 to 85.3 ± 38.9 μg/dL (p = 0.001), while eGFR levels decreased from 106.6 ± 10.3 to 102.1 ± 19.4 mL/min per 1.73 m² (p = 0.025). Zn correlated positively with eGFR at 6-month (r = 0.252, p = 0.037) and 12-month (r = 0.41, p = 0.001) follow-ups. Multiple linear regression analyses including baseline variables of age, sex, BMI, %WL, and diabetes identified Zn and %WL as independent predictors of eGFR at 12-month follow-up. There was no evidence of multicollinearity among these variables. Despite positive association between %WL and △eGFR (r = 0.222, p = 0.031), no correlation was noted between %WL and △Zn (r = - 0.129, p = 0.40).

CONCLUSION

The results demonstrated a positive relationship between post-LSG serum zinc levels and preservation of renal function among patients with obesity in a surgical setting. Large-scale studies are warranted to support the findings.

Exercise alters cardiovascular and renal pregnancy adaptations in female rats born small on a high-fat diet

Intrauterine growth restriction programs adult cardiorenal disease, which may be exacerbated by pregnancy and obesity. Importantly, exercise has positive cardiovascular effects. This study determined if high-fat feeding exacerbates the known adverse cardiorenal adaptations to pregnancy in rats born small and whether endurance exercise can prevent these complications. Uteroplacental insufficiency was induced by bilateral uterine vessel ligation (Restricted) or sham (Control) surgery on embryonic day 18 (E18) in Wistar-Kyoto rats. Female offspring consumed a Chow or high-fat diet (HFD) from weaning and were randomly allocated to either a sedentary (Sedentary) or an exercise protocol at 16 wk; exercised before and during pregnancy (Exercise), or exercised during pregnancy only (PregEx). Systolic blood pressure was measured prepregnancy and rats were mated at 20 wk. During pregnancy, systolic blood pressure (E18) and renal function (E19) were assessed. Sedentary HFD Control females had increased estimated glomerular filtration rate (eGFR) compared with Chow. Compared with Control, Sedentary-Restricted females had increased eGFR, which was not influenced by HFD. Renal function was not affected by exercise and prepregnancy blood pressure was not altered. Restricted Chow-fed dams and dams fed a high-fat diet had a greater reduction in systolic blood pressure during late gestation, which was only prevented by Exercise. In summary, high-fat fed females born small are at a greater risk of altered cardiorenal adaptations to pregnancy. Although cardiovascular dysfunction was prevented by Exercise, renal dysfunction was not affected by exercise interventions. This study highlights that modifiable risk factors can have beneficial effects in the mother during pregnancy, which may impact fetal growth and development.

Osteopontin's relationship with malnutrition and oxidative stress in adolescents. A pilot study

Osteopontin (OPN) is a protein involved in inflammatory illnesses such as fibrosis and cancer; its overexpression in cardiovascular diseases promotes the biomineralization of blood vessels and other soft tissues. Moreover, there is an active component of oxidative stress related with those diseases. The present study relates serum OPN levels with nutritional condition and oxidative stress in a group of adolescents. Anthropometric measurements were performed, and fasting blood samples were analyzed to determine OPN concentrations, blood chemistry parameters (glucose, triglycerides, total cholesterol, urea, uric acid, and creatinine) and oxidative stress biomarkers (Paraoxonase-1, Glutathione S-Transferase, Catalase, NAD(P)H Quinone Oxidoreductase, free carbonyl groups and malondialdehyde). Adolescents were categorized according to body mass index (BMI) and metabolic syndrome (MetS) criteria. We found increased OPN serum concentrations in overweight and obese adolescents, as well as in adolescents with MetS. Rises in OPN correlated with arm circumference and biomarkers of lipid peroxidation; with regard to serum glucose there was a trend to positive correlation. Our results suggest that serum OPN is associated to nutritional status and could be considered as an early biomarker of low-grade inflammation and probably the early biomineralization of soft tissues in adolescence.

Comparison of eGFR formulas in determining chronic kidney disease stage in bariatric patients and the impact on perioperative outcomes

BACKGROUND

Chronic kidney disease (CKD) independently increases the risk of 30-day adverse outcomes following metabolic and bariatric surgery (MBS). However, no studies have evaluated the stage of CKD at which increased perioperative risk is manifested. Here, we correlate 30-day major morbidities after MBS with extent of renal disease based on CKD Stage.

OBJECTIVES

To determine the impact of CKD stage on perioperative outcomes after bariatric surgery.

SETTING

Academic Hospital.

METHODS

From the 2017 Metabolic and Bariatric Surgery Quality Improvement Program (MBSAQIP) database, we identified patients with CKD who underwent sleeve gastrectomy or laparoscopic gastric bypass surgery. Glomerular filtration rates (GFRs) were calculated and cohorts were generated based on CKD Stage. Complication rates and rates of morbidity and mortality were compared between stages, and strengths of correlation were calculated.

RESULTS

GFR and CKD Stage were calculated for 150,283 patients. There was a significant increase in the risk of major morbidity at each progressive stage of CKD (P < .001 for all compared stages). There was a strong positive linear correlation between increasing CKD Stage and total morbidity (r² = .983), including reoperation ( r² = .784), readmission (r² = .936), unplanned ICU transfer (r² = .853), and aggregate complications such as pulmonary (r² = .900), bleeding (r² = .878), or progressive worsening of renal function (r² = .845). In logistic regression, for every 10-point decrease in GFR, odds of total morbidity increased by 6%.

CONCLUSION

An increased risk of perioperative complications may be seen in early stages of CKD, and risk is compounded in more advanced stages. Bariatric surgical candidates should be counseled on their increased risk of surgical complications even with mild CKD, and the benefits of bariatric surgery should be carefully weighed against significantly increased risks of complications in severe CKD.

Metabolic Phenotypes and Chronic Kidney Disease: A Cross-Sectional Assessment of Patients from a Large Federally Qualified Health Center

The purpose of this study is to determine if renal function varies by metabolic phenotype. A total of 9599 patients from a large Federally Qualified Health Center (FQHC) were included in the analysis. Metabolic health was classified as the absence of metabolic abnormalities defined by the National Cholesterol Education Program Adult Treatment Panel III criteria, excluding waist circumference. Obesity was defined as body mass index >30 kg/m2 and renal health as an estimated glomerular filtration rate (eGFR) >60 mL/min/1.73 m2. Linear and logistic regressions were used to analyze the data. The metabolically healthy overweight (MHO) phenotype had the highest eGFR (104.86 ± 28.76 mL/min/1.72 m2) and lowest unadjusted odds of chronic kidney disease (CKD) (OR = 0.46, 95%CI = 0.168, 1.267, p = 0.133), while the metabolically unhealthy normal weight (MUN) phenotype demonstrated the lowest eGFR (91.34 ± 33.28 mL/min/1.72 m2) and the highest unadjusted odds of CKD (OR = 3.63, p < 0.0001). After controlling for age, sex, and smoking status, the metabolically unhealthy obese (MUO) (OR = 1.80, 95%CI = 1.08, 3.00, p = 0.024) was the only phenotype with significantly higher odds of CKD as compared to the reference. We demonstrate that the metabolically unhealthy phenotypes have the highest odds of CKD compared to metabolically healthy individuals.

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.

Prognostic Utility of KDIGO Urine Output Criteria After Cardiac Surgery

OBJECTIVES

Kidney Disease: Improving Global Outcomes (KDIGO) guidelines include assessment of creatinine and urine output to identify acute kidney injury (AKI). Whether urine output is an accurate indicator of AKI after cardiac surgery, however, is unclear. The authors' goal was to examine whether cardiac surgery patients who fulfilled criteria for AKI by KDIGO urine output criteria also demonstrated kidney injury by elevated creatinine, other kidney biomarkers, or had worse clinical outcomes.

DESIGN

Secondary analysis of prospectively collected data from a clinical trial, "6% Hydroxyethyl starch 130/0.4 in Cardiac Surgery (NCT02192502)."

SETTING

Academic, quaternary care hospital.

PARTICIPANTS

Patients undergoing elective aortic valve replacement INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: One hundred forty-one patients were classified into AKI stage by KDIGO urine output criteria within 24 hours after surgery. Kidney biomarkers (serum creatinine, urinary neutrophil gelatinase-associated lipocalin [NGAL], urinary interleukin-18 [IL-18]) and hospital and intensive care unit length of stay were analyzed across AKI stages. Urine output criteria classified four times as many patients with AKI than creatinine criteria (95 [67%] v 21 [15%]). Most patients meeting KDIGO urine output criteria for AKI postoperatively did not satisfy KDIGO creatinine criteria for AKI within one week (77 of 95 [81%]) or six-to-12 months (27 of 29 [93%]). Higher AKI stage assessed by urine output was not associated with higher NGAL, IL-18, or longer hospital or intensive care unit stays.

CONCLUSIONS

Acute kidney injury classified by KDIGO urine output criteria was not associated with other biomarkers of kidney injury or worse patient outcomes. These data suggested that KDIGO urine output criteria after cardiac surgery may overclassify AKI stage; further research is needed.

Indicator of early kidney injury in adolescents with polycystic ovary syndrome: Can urine NGAL level be?

INTRODUCTION AND PURPOSE

The Urinary Neutrophil-gelatinase associated lipocalin (NGAL) levels which are a biomarker for early diagnosis of kidney damage that may develop in patients with Polycystic Ovary Syndrome (PCOS) were investigated in the study.

MATERIAL AND METHODS

The 30 patients diagnosed with Polycystic Ovarian Syndrome between the ages of 13 and 18 who applied to the Yuzuncu Yil University General Children's Outpatient Clinic were included in the PCOS group and 30 healthy adolescents without any known acute or chronic illness and drug use were included in the control group.

FINDINGS

Urine NGAL value was 842.204 ± 21.561 in PCOS group and 775.379 ± 23.98 in control group. NGAL level in PCOS group was statistically significantly higher than control group (p: .045). When we examine the relationship between dyslipidemia and PCOS; While dyslipidemia was positive in 10 (33.7%) patients in the PCOS group, it was negative in 20 (66.7%) patients. While 1 patient had dyslipidemia, 29 patients did not have dyslipidemia in the control group. A significant relationship was found between dyslipidemia and PCOS (p: .005).

CONCLUSION

We found that subclinical kidney dysfunction started in early stage patients in PCOS in our study. The urine NGAL level was thought to increase in response to increased oxidative stress in PCOS. We found no relationship between, insulin resistance and urea, BUN, creatinine and NGAL levels. However, we found a negative correlation between NGAL level and LDL. In addition, dyslipidemia, insulin resistance and ALT elevation were detected in the PCOS group.

Obesity is a predictor of increased morbidity after tracheostomy

OBJECTIVE

The purpose of this study was to analyze the relationship between body mass index (BMI) and 30-day morbidity and mortality risk in patients undergoing tracheostomy using the American College of Surgeons National Quality Improvement Program (ACS-NSQIP).

STUDY DESIGN

This is a retrospective, cross-sectional, cohort study.

SETTING

Patients were identified with Current Procedural Terminology codes in the ACS-NSQIP database.

SUBJECTS AND METHODS

Patients who underwent tracheostomy from 2005 to 2018 were queried. They were stratified into four BMI classes and matched to normal BMI cohorts. Multivariate logistic regression was used to identify independent predictors for complications, readmissions, and unplanned reoperations within 30 days.

RESULTS

Among 3784 patients meeting inclusion and exclusion criteria, obesity was shown to be a significant independent risk factor for overall complications (OR 1.439, 95% CI 1.226-1.689, p < 0.001), postoperative acute renal failure (OR 10.715, 95% CI 1.213-94.646, p = 0.033), and unplanned readmissions (OR 1.702, 95% CI 1.095-2.647, p = 0.018). A significantly lower rate of postoperative transfusions was observed for obese patients (OR 0.581, 95% CI 0.432-0.781, p < 0.001).

CONCLUSIONS

Obesity was found to be independently associated with an increased risk of overall complication, developing acute renal failure, and having an unplanned 30-day readmission following tracheostomy. The risk of postoperative transfusion appears to be lower in obese patients.

LEVEL OF EVIDENCE

4.

Gender-biased kidney damage in mice following exposure to tobacco cigarette smoke: More protection in premenopausal females

Multiple clinical studies documented renal damage in chronic cigarette smokers (CS) irrespective of their age and gender. Premenopausal female smokers are known to exert a certain cardiovascular and renal protection with undefined mechanisms. Given the multiple demographic variables within clinical studies, this experimental study was designed to be the first to assess whether gender‐biased CS‐induced kidney damage truly exists between premenopausal female and age‐matched C57Bl6J male mice when compared to their relative control groups. Following 6 weeks of CS exposure, cardiac function, inflammatory marker production, fibrosis formation, total and glomerular ROS levels, and glomerulotubular homeostasis were assessed in both genders. Although both CS‐exposed male and female mice exhibited comparable ROS fold change relative to their respective control groups, CS‐exposed male mice showed a more pronounced fibrotic deposition, inflammation, and glomerulotubular damage profile. However, the protection observed in CS‐exposed female group was not absolute. CS‐exposed female mice exhibited a significant increase in fibrosis, ROS production, and glomerulotubular alteration but with a pronounced anti‐inflammatory profile when compared to their relative control groups. Although both CS‐exposed genders presented with altered glomerulotubular homeostasis, the alteration phenotype between genders was different. CS‐exposed males showed a significant decrease in Bowman's space along with reduced tubular diameter consistent with an endocrinization pattern of chronic tubular atrophy, suggestive of an advanced stage of glomerulotubular damage. CS‐exposed female group, on the other hand, displayed glomerular hypertrophy with a mild tubular dilatation profile suggestive of an early stage of glomerulotubular damage that generally precedes collapse. In conclusion, both genders are prone to CS‐induced kidney damage with pronounced female protection due to a milder damage slope.

Caloric Intake in Renal Patients: Repercussions on Mineral Metabolism

The aim of this paper is to review current knowledge about how calorie intake influences mineral metabolism focussing on four aspects of major interest for the renal patient: (a) phosphate (P) handling, (b) fibroblast growth factor 23 (FGF23) and calcitriol synthesis and secretion, (c) metabolic bone disease, and (d) vascular calcification (VC). Caloric intake has been shown to modulate P balance in experimental models: high caloric intake promotes P retention, while caloric restriction decreases plasma P concentrations. Synthesis and secretion of the phosphaturic hormone FGF23 is directly influenced by energy intake; a direct correlation between caloric intake and FGF23 plasma concentrations has been shown in animals and humans. Moreover, in vitro, energy availability has been demonstrated to regulate FGF23 synthesis through mechanisms in which the molecular target of rapamycin (mTOR) signalling pathway is involved. Plasma calcitriol concentrations are inversely proportional to caloric intake due to modulation by FGF23 of the enzymes implicated in vitamin D metabolism. The effect of caloric intake on bone is controversial. High caloric intake has been reported to increase bone mass, but the associated changes in adipokines and cytokines may as well be deleterious for bone. Low caloric intake tends to reduce bone mass but also may provide indirect (through modulation of inflammation and insulin regulation) beneficial effects on bone. Finally, while VC has been shown to be exacerbated by diets with high caloric content, the opposite has not been demonstrated with low calorie intake. In conclusion, although prospective studies in humans are needed, when planning caloric intake for a renal patient, it is important to take into consideration the associated changes in mineral metabolism.

Physical exercise associated with vitamin D chronic supplementation reduces kidney injury induced by monosodium glutamate

The aim was to evaluate the effects of chronic vitamin D (VD) supplementation associated with regular swimming over renal histomorphometric aspects in obese rats. Thirty Wistar male rats (5 days old) were used. Twenty four rats were given subcutaneous injections of monosodium glutamate (MSG; 4 g/kg), and six control rats were given an equimolar saline solution. At 21-days-old, the MSG-treated rats were randomly distributed among sedentary animals (S) and exercised (E, swimming; 3x/week). These groups were subdivided into groups orally supplemented with VD (12 μg/kg; 3x/week) or not supplemented (NS), totaling Five experimental groups (n = 6 rats/group): MSG, MSG-SVD, MSG-ENS, MSG-EVD and control groups. In MSG-obese rats, there was such as a decrease in the diameter of the, glomerular tuft, Bowman's capsule, Bowman's space areas, and renal cortical thickness, compared to the control group. In MSG-SVD, MSG-ENS, and MSG-EVD animals, there was an increase in the cortical thickness in relation to the MSG group. In MSG-ENS and MSG-EVD animals, there was a reduction of tubular degeneration in relation to the MSG group. We conclude that physical exercise associated with Vitamin D supplementation can prevent of renal injury, increasing the thickness of the renal cortex and decrease the tubular degeneration.

Incremental Effect of Aging on Obesity-Related Incident Chronic Kidney Disease in the Korean General Population

OBJECTIVES

Obesity may increase the risk of kidney function decline. However, few studies have addressed how age modifies obesity-associated risk of chronic kidney disease (CKD) in the Asian general population.

DESIGN

A community-based prospective cohort study.

SETTING AND PARTICIPANTS

6538 Korean general population with normal kidney function from the Korean Genome and Epidemiology Study Database.

METHODS

Participants were stratified according to age (40-49, 50-59, and 60-69 years old) and body mass index [≥18.5-<23 (normal-weight), ≥23-<27.5 (overweight), and ≥27.5 (obese)]. We conducted Kaplan-Meier and multivariable-adjusted Cox regression analyses to investigate the association of aging and obesity with incident CKD.

RESULTS

During the 12-year follow-up, an overall incidence rate of CKD was 6.1 cases per 1000 person-years. Obese, but not overweight, people had an increased risk of incident CKD compared with normal-weight people in multivariable models adjusted for metabolic factors. When analyzed by 10-year increments, this association was significant only in 60-69-year-old individuals. Kaplan-Meier analysis showed that the incidence of CKD associated with overweight or obesity showed an accentuated increase with age. With reference to normal-weight individuals aged 40-49 years, the adjusted hazard ratio of CKD increased with age regardless of body mass index, and the positive association between obesity and incident CKD was more prominent with increasing age.

CONCLUSIONS AND IMPLICATIONS

Obesity-associated risk of incident CKD was accentuated in older people, and this association was independent of metabolic abnormalities.

Collapsing focal segmental sclerosis in an HIV-negative patient

Collapsing focal segmental glomerulosclerosis (FSGS) is classically seen in HIV-infected patients and carries a dismal prognosis. It can also occur in HIV-negative patients in which case, early aggressive treatment with glucocorticoids may be helpful with improvement in both proteinuria and renal function.

Clinical Performance of Nonvitamin K Antagonist Oral Anticoagulants in Real-World Obese Patients with Atrial Fibrillation

The prevalence of both atrial fibrillation (AF) and obesity has steadily increased. Nonvitamin K antagonist oral anticoagulants (NOACs) have been shown to be more effective and safer than vitamin K antagonists (VKAs) for long-term stroke prevention in patients with nonvalvular AF. There are still limited data in the literature regarding performance of NOACs in obese patients with AF in the “real world.” The aim of our study was to compare the safety and effectiveness of NOACs versus well-controlled VKA therapy in obese AF patients in a “real-world” setting. Here, we have considered patients with AF and obesity (body mass index [BMI] > 30 kg/m2) on NOAC or VKA therapy included in the multicenter Atrial Fibrillation Research Database (NCT03760874). The occurrence of major bleedings (MBs) and thromboembolic events (composite of ischemic stroke, transient ischemic attack, and systemic embolism) was respectively considered primary safety and effectiveness outcomes. We identified 1,047 AF patients with obesity who received NOAC (n = 272) or VKA (n = 775) treatment. After propensity score matching analysis, 248 NOAC and 496 VKA recipients with similar clinical characteristics, including BMI (34.8 ± 3.4 in NOAC vs. 35.1 ± 3.8 in the VKA group; p = 0.50), were evaluated. The mean follow-up was 39 ± 7 months. The incidence rate of thromboembolic events was 1.10 per 100 person-years (0.67 in NOAC vs. 1.28 in the VKA group; hazard ratio [HR]: 0.52; 95% confidence interval [CI]: 0.22–1.22; p = 0.19). The incidence rate of MB was 1.9 per 100 person-years (1.1 in NOAC vs. 2.28 in the VKA group; HR: 0.46; 95% CI: 0.24–0.88; p = 0.04). The incidence rate of intracranial hemorrhage was 0.4 per 100 person-years (0.27 in NOAC vs. 0.47 in the VKA group; HR: 0.57; 95% CI: 0.12–2.73; p = 0.48). A positive net clinical benefit (NCB) of NOACs over VKAs was found (+0.91). Presence of anemia (HR: 1.75; p = 0.003) and concomitant use of antiplatelet drugs (HR: 2.41; p = 0.001) were found to be independent predictors of MB; moreover, age (HR: 1.65; p = 0.003) was an independent predictor of thromboembolic events. Our data support the hypothesis of safe and effective use of NOACs in patients with AF and obesity, justified by a statistically significant lower incidence of MB and a favorable NCB over VKAs.

Association of obesity and muscle mass with risk of albuminuria in renal transplant recipients

BACKGROUND

Increased albuminuria is a predictor of graft loss in kidney graft recipients. It is unknown whether obesity is an independent risk factor for the development of increased albuminuria in this population. The aim of this study was to elucidate the association between obesity and albuminuria in renal transplant recipients.

METHODS

We enrolled 330 renal transplant recipients and prospectively collected demographic, anthropomorphic, clinical and laboratory variables susceptible to influence albumin excretion. The outcome was albuminuria, measured using accurately timed urine collections. Data from 201 patients were analyzed after exclusion of participants with missing data and patients enrolled less than 6 months since renal transplantation. Analysis was carried out for an early and a late period, defined according to the 2.4-year median follow-up time.

RESULTS

Body mass index (BMI), waist circumference and urinary creatinine excretion rate were independent predictors of albuminuria in the late post-transplant period, indicating that the predictive value of body mass index for albuminuria is related to both increased abdominal fat mass and increased muscle mass. BMI was an independent predictor of microalbuminuria. Waist circumference and urinary creatinine were independent predictors of microalbuminuria for values above certain cutoffs: 110% of the accepted thresholds defining abdominal obesity and 1500 mg/day, respectively.

CONCLUSIONS

These associations, which have not previously been reported, suggest, but do not prove, that an imbalance between metabolic demand and nephron mass may be responsible for increased albuminuria in the renal transplant population.

Treatment With Gemfibrozil Prevents the Progression of Chronic Kidney Disease in Obese Dahl Salt-Sensitive Rats

Recently, we reported that Dahl salt-sensitive leptin receptor mutant (SS^LepRmutant) rats exhibit dyslipidemia and renal lipid accumulation independent of hyperglycemia that progresses to chronic kidney disease (CKD). Therefore, in the current study, we examined the effects of gemfibrozil, a lipid-lowering drug (200 mg/kg/day, orally), on the progression of renal injury in SS and SS^LepRmutant rats for 4 weeks starting at 12 weeks of age. Plasma triglyceride levels were markedly elevated in the SS^LepRmutant strain compared to SS rats (1193 ± 243 and 98 ± 16 mg/day, respectively). Gemfibrozil treatment only reduced plasma triglycerides in the SS^LepRmutant strain (410 ± 79 mg/dL). MAP was significantly higher in the SS^LepRmutant strain vs. SS rats at the end of the study (198 ± 7 vs. 165 ± 7 mmHg, respectively). Administration of gemfibrozil only lowered MAP in SS^LepRmutant rats (163 ± 8 mmHg). During the course of the study, proteinuria increased to 125 ± 22 mg/day in SS rats. However, proteinuria did not change in the SS^LepRmutant strain and remained near baseline (693 ± 58 mg/day). Interestingly, treatment with gemfibrozil increased the progression of proteinuria by 77% in the SS^LepRmutant strain without affecting proteinuria in SS rats. The renal injury in the SS^LepRmutant strain progressed to CKD. Moreover, the kidneys from SS^LepRmutant rats displayed significant glomerular injury with mesangial expansion and increased renal lipid accumulation and fibrosis compared to SS rats. Treatment with gemfibrozil significantly reduced glomerular injury and lipid accumulation and improved renal function. These data indicate that reducing plasma triglyceride levels with gemfibrozil inhibits hypertension and CKD associated with obesity in SS^LepRmutant rats.

Application of vancomycin in patients with augmented renal clearance

OBJECTIVE

To analyse the influence of factors on the steady-state trough concentration (C_trough) of vancomycin, especially in patients with augmented renal clearance, and to provide a reference for clinical application.

METHODS

Data on patient demographics, routine blood examination, hepatic function and kidney function were collected from May 2013 to October 2016. A total of 292 patients were enrolled and correlations between C_troughof vancomycin and other test indices were analysed by SPSS software.

RESULTS

The patients with augmented renal clearance were significantly younger with relatively lower C_trough values and higher weight, ALB and PLT compared to others. And age was the most important factor of C_troughamong subgroups of ARC.

CONCLUSIONS

Inpatients with augmented renal clearance,vancomycin C_trough was mainly affected by age. Clinicians and pharmacists should adjust the dosage regimen in a timely manner based on therapeutic drug monitoring and these influencing factors.

Peri-renal fat thickness is positively associated with the urine albumin excretion rate in patients with type 2 diabetes

BACKGROUNDS

Albuminuria, the earliest clinical manifestation of diabetic kidney disease (DKD), is a major prognostic indicator of renal progression. Obesity itself is associated with the development of DKD and accelerates its progression. Accumulation of peri-renal fat on the kidneys can damage kidney function. Measuring the perirenal fat thickness (PFT) by ultrasound is a non-invasive method to measure ectopic fat deposition on the kidney. In this study, we aim to obtain the association between albuminuria and PFT.

METHODS

Eighty-nine subjects with type 2 diabetes mellitus (T2DM) were enrolled. Albuminuria was defined as a urine albumin-to-creatinine ratio (UACR) ≧30 mg/g. Measurement of the PFT was performed by B-mode ultrasound (Toshiba SSA-680A) and determined from the surface of the abdominal musculature to the surface of kidney. Pearson correlation coefficients were determined to test the significant independent relationship between the PFT and demographic, anthropometric and laboratory parameters.

RESULTS

Patients were divided into those with (n = 66) and without (n = 23) albuminuria. PFT (odds ratio [OR], 19.3; 95% CI, 2.25-165.00; p = 0.01) was significantly correlated with albuminuria based on multiple logistic regression analysis. Additionally, linear regression confirmed that degree of albuminuria has a positive association with the PFT (r = 0.233; p = 0.03).

CONCLUSIONS

Our study showed that an increased PFT is positively associated with the albuminuria among patients with T2DM. Our findings suggest that measurement of the PFT may represent a helpful tool to assess the risk of developing albuminuria in patients with T2DM.

Assessment of Kidney Function in Patients With Extreme Obesity: A Narrative Review

Objectives:

To discuss the evidence and caveats associated with estimated and measured creatinine clearance (eClCr and mClCr) and glomerular filtration rate (eGFR and mGFR) assessments of kidney function in patients with more extreme forms of obesity.

Data Sources:

PubMed (1976 to mid-May 2020) was used, with bibliographies of retrieved articles searched for additional articles.

Study Selection and Data Extraction:

Articles using gold standard mGFR to evaluate eClCr, mClCr, and eGFR assessments of kidney function in patients with more extreme forms of obesity were included.

Data Synthesis:

The overestimation of GFR by mClCr is well established, but mClCr is an alternative to mGFR assessments for determining medication dosing in patients with extremes of body size or muscle mass, or in patients receiving narrow therapeutic index medications when eGFR is likely to be inaccurate. The vast majority of studies comparing eGFR assessments with gold standard indicators of kidney function were attempts to validate eGFR equations for diagnosing and staging chronic kidney disease (CKD).

Relevance to Patient Care and Clinical Practice:

For dosing medications in patients with stable kidney function and extreme obesity, a deindexed 4-variable Modification of Diet in Renal Disease or CKD Epidemiology Collaboration equation is an alternative to Cockcroft-Gault. Consistent use of the same equation by provider and between providers within any given setting is of paramount importance.

Conclusions:

In patients with extreme obesity and stable kidney function, eClCr or eGFR using deindexed values provides estimates of function for dosing adjustments of medications with elimination by the kidneys, but more research is needed with respect to the best size descriptor to use with estimating equations.

Obesity-Related Glomerulopathy: A Latent Change in Obesity Requiring More Attention

BACKGROUND

Obesity has become a major public health problem, and the prevalence of kidney diseases has increased in parallel. Among kidney diseases caused by metabolic disorders, obesity-related glomerulopathy (ORG) is secondary to obesity.

SUMMARY

ORG is mainly caused by glomerular hyperfiltration, dysregulation of hormone and cytokine secretion in adipose tissues, and ectopic lipid accumulation in renal cells. ORG is pathologically characterized by glomerular hypertrophy, with or without focal and segmental glomerulosclerosis. Patients with ORG usually present with proteinuria concomitant with metabolic disorders such as dyslipidemia and hypertension. Weight loss, RAAS inhibitors, and improved insulin resistance can reduce the progression of ORG.

CONCLUSION

ORG is a growing renal pathological change in obese individuals, and a comprehensive understanding of the disease is pivotal to avoid its occurrence and improve quality of life for those with obesity. Key Messages:This review comprehensively describes the characteristics of ORG in pathological changes, clinical manifestations, pathogeneses and treatments.

Increased body mass index above the upper normal limit is significantly associated with renal dysfunction among community-dwelling persons

PURPOSE

Body mass index (BMI) is a simple index of weight-to-height that is commonly used to classify people as underweight, overweight or obesity, and high BMI has been clearly linked to increased risk of illness in adults. However, few studies have examined the significance of upper normal weight as a risk factor for the development of chronic kidney disease (CKD) in the general Japanese population.

METHODS

We conducted a prospective cohort study designed as part of the Nomura study. We recruited a random sample of 421 men aged 67 ± 10 (mean ± standard deviation; range 24-95) years and 565 women aged 68 ± 9 (22-84) years during their annual health examination in a single community. We examined the relationship between quartiles of baseline BMI and renal dysfunction after a 3-year evaluation based on estimated glomerular filtration rate (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations modified by the Japanese coefficient. CKD was defined as having dipstick-positive proteinuria (≥ 1 +) or a low eGFR (< 60 mL/min/1.73 m²).

RESULTS

Of the 986 participants, a total of 134 (13.6%) participants, including 72 (17.1%) men and 62 (11.0%) women, received a new diagnosis of CKD during the study period, and 25 (9.7%), 19 (8.0%), 47 (19.0%), and 43 (17.8%) diagnoses were received in the BMI-1 (BMI, < 20.7 kg/m²), BMI-2 (BMI, 20.7 to 22.5 kg/m²), BMI-3 (BMI, 22.6 to 24.4 kg/m²), and BMI-4 (BMI ≥ 24.5 kg/m²) groups, respectively. Using BMI-2 as the reference group, the non-adjusted odds ratio (OR) (95% confidence interval) for CKD was 2.70 (1.53-4.75) for BMI-3 and 2.49 (1.40-4.42) for BMI-4, and the multivariable-adjusted OR was 2.52 (1.40-4.56) for BMI-3 and 2.30 (1.26-4.22) for BMI-4.

CONCLUSIONS

Increased BMI from upper normal weight is strongly associated with the development of CKD in community-dwelling persons.

Single-Nephron GFR in Patients With Obesity-Related Glomerulopathy

Introduction

Obesity-related glomerulopathy (ORG) is a slowly progressive kidney disease occurring in association with obesity. It is characterized histopathologically by glomerulomegaly, likely caused by single-nephron hyperfiltration that has not been demonstrated in humans because of technical difficulty in measuring single-nephron glomerular filtration rate (SNGFR) in the clinical setting.

Methods

Total glomerular number per kidney, with or without global glomerulosclerosis, was estimated by the combination of cortical volume assessment via unenhanced computed tomography and biopsy-based stereology. Mean glomerular volume was calculated from the measured area of glomerular tufts. Both SNGFR and single-nephron urinary protein excretion (SNUPE) were estimated by dividing values for estimated glomerular filtration rate and urinary protein excretion by the number of nonsclerotic glomeruli. Living kidney donors were used as healthy controls.

Results

A total of 48 ORG patients with average nonsclerotic glomerular numbers of 456,000 ± 235,000 per kidney were included. The values for SNGFR in ORG patients with chronic kidney disease (CKD) stages 1 and 2 were higher than for nonobese and obese controls (97 ± 43 vs. 59 ± 21 vs. 64 ± 21 nl/min, respectively, P = 0.001). Nonsclerotic glomerular number decreased with advancing stages of renal functional impairment. The presence of ORG with more advanced CKD stages was associated with lower SNGFR and marked elevation in SNUPE levels, with no difference in the mean glomerular volume between the stages.

Conclusions

These results provide functional evidence for single-nephron hyperfiltration in patients with ORG, and identify compensatory failure to maintain effective SNGFR as a feature of advanced-stage ORG.

Effect of laparoscopic sleeve gastrectomy on renal function in obese patients

BACKGROUND

To investigate the clinical efficacy and mechanism of laparoscopic sleeve gastrectomy (LSG) in improving renal function in obese patients.

METHODS

We retrospectively reviewed the anthropometric indices (waist circumference, hip circumference and body mass index (BMI)), renal function indices (serum creatinine, urea and urinary albumin:creatinine ratio (UACR)), serum inflammatory indices (C-reactive protein, interleukin-6 and tumour necrosis factor-α) and an adipose factor (leptin) in 50 patients with obesity (BMI ≥32.5 kg/m² ) who underwent LSG in our hospital from January 2018 to January 2019.

RESULTS

Patients constituted 23 men and 27 women, with an average age of 32.5 ± 8.7 years and BMI of 43.99 ± 8.29 kg/m² . Body weight and BMI 1 month post-operatively were significantly lower than preoperatively (P < 0.05), and the renal function indices serum creatinine, urea and UACR, improved significantly 3 months post-operatively (P < 0.05). C-reactive protein, interleukin-6 and tumour necrosis factor-α levels improved significantly 3 months post-operatively (P < 0.05), while leptin levels decreased significantly 1 month post-operatively (P < 0.05). Six months post-operatively, the remission rates for type 2 diabetes mellitus, sleep apnoea syndrome and hypertension were 83.8%, 92.9% and 88.6%, respectively.

CONCLUSIONS

LSG led to body weight loss and significantly improved serum creatinine, urea and UACR values in patients with obesity, which may be related to changes in adipocytokines and inflammatory factors, post-operatively. LSG is expected to become a new treatment to prevent or treat renal insufficiency caused by obesity.