Is the presence of microalbuminuria a relevant marker of kidney disease?

Increasing obstructive sleep apnea risk is associated with albuminuria in Korean adults: cross-sectional analysis

Several studies have shown an association between albuminuria and obstructive sleep apnea (OSA). However, studies on the relationship between the STOP-BANG questionnaire that can screen for OSA and microalbuminuria are still insufficient. Therefore, this study attempted to clarify the relationship between microalbuminuria and OSA risk using the STOP-BANG questionnaire in Korean adults. A total of 7478 participants (3289 men and 4189 women) aged over 40 were enrolled in the Korean National Health and Nutrition Examination Survey from 2019 to 2020. STOP-BANG questionnaire to screen OSA was obtained from subjects. The urinary albumin/creatinine ratio (ACR) and proteinuria were measured via a single dipstick to evaluate renal function. The high OSA risk group had a higher mean ACR value than the low OSA risk group (36.8 ± 172.2 vs 17.7 ± 82.5; P < 0.001). The proportion of subjects with values of 30 ≤ ACR < 300 mg/g (11.9% vs 6.1%; P < 0.001) and ACR > 300 mg/g (2.1% vs 0.7%; P < 0.001) was significantly higher in high OSA risk group. Multivariate logistic regression results confirmed that microalbuminuria (OR 1.279, 95% confidence interval (CI) 1.068-1.532, P = 0.008) was significantly correlated with high OSA risk. In addition, significant correlation with high OSA risk was also found in macroalbuminuria (OR 1.684, 95% CI 1.073-2.530, P = 0.022) and proteinuria (OR 1.355, 95% CI 1.030-1.783, P = 0.030). We confirmed a significant correlation between high OSA risk and albuminuria/proteinuria in Korean adults. Therefore, renal function evaluation is required in high OSA risk patients, and OSA diagnosis through PSG test and treatment is necessary.

Early kidney damage in diabetic adolescents with increased blood pressure and glomerular hyperfiltration

BACKGROUND

The early impact of type 1 diabetes mellitus (DM1), increased blood pressure and glomerular hyperfiltration (GHF) on kidney damage in adolescents using two urinary markers of kidney injury - neutrophil gelatinase-associated lipocalin (uNGAL) and transferrin (uTransf) - was assessed.

METHODS

The study group consisted of 80 adolescents with DM1, of whom 42 were patients with increased blood pressure (IBP), and 38 were patients with normal blood pressure (NBP). Blood pressure was assessed by 24-hour ambulatory blood-pressure monitoring. All patients showed estimated glomerular-filtration rates (eGFRs) above 90 mL/min/1.73 m2. The control group consisted of 19 healthy, age and gender-matched adolescents.

RESULTS

All diabetic children showed a significant increase in uNGAL (P<0.001). This increase was not related to blood pressure. The uNGAL was elevated in all patients with normal albuminuria, normal eGFR and NBP. The concentration of uTransf was not increased in the entire studied group and was not related to blood pressure. Children with GHF had significantly higher levels of both uTransf (P=0.010) and uNGAL (P<0.001). In patients with GHF, blood pressure was normal. Patients with IBP showed a significantly higher value for triglycerides (r=0.247; P=0.032) and a longer duration of diabetes (r=0.264; P=0.019).

CONCLUSIONS

Diabetes is the leading risk factor for early kidney injury. However, increased blood pressure does not lead to kidney damage, at least in the early stage of DM1. The uNGAL is the early indicator of kidney injury and increases in patients with normal albuminuria, normal glomerular filtration and normal blood pressure. Glomerular hyperfiltration seems to be a marker of diabetic-kidney involvement.

Sex-specific interactive effect of melamine and DEHP on a marker of early kidney damage in Taiwanese adults: A national population-based study from the Taiwan Biobank

Taiwan had the high incidence of chronic kidney disease (CKD) worldwide. Our objective was to examine associations between daily exposure of phthalates and melamine, two common nephrotoxins, and kidney damage risk in a well-established nationwide cohort. Study subjects were from Taiwan Biobank (TWB) with existing data of questionnaire and biochemical examinations. Average daily intake (ADI) levels of melamine and seven parental phthalates, including DEHP (di-2-ethylhexylphthalate), DiBP (Dibutyl phthalate), DnBP (Di-n-butyl phthalate), BBzP (Butyl benzyl phthalate), DEP (Diethyl phthalate), and DMP (Dimethyl phthalate) were estimated using a creatinine excretion-based model from urine melamine and 10 phthalate metabolites. Urine microalbumin to creatinine ratio (ACR) was used to represent for the outcome of kidney damage. Two statistical strategies were used: First, a weighted quantile sum (WQS) regression model to select the most important exposure variables of ADI levels of phthalates and melamine associated with ACR; Second, to examine effects of those most important exposure variables on ACR in multivariable linear regression models. In total, 1153 eligible adults were left for analyses. Of them, 591 (51.3%) and 562 (48.7%) were men and women, respectively, with a median age of 49 years old. By WQS, a significant and positive association was found between ADI of melamine and phthalates and ACR (β = 0.14, p = 0.002). ADI levels of melamine had the highest weight (0.57), followed by DEHP (0.13). Next, examining the two most important exposures in association with ACR, we found that the higher the melamine and DEHP intakes, the higher the ACR levels were found. An interaction effect was also found between melamine and DEHP intakes on urine ACR (p = 0.015). This result was more prominent in men (p = 0.008) than in women (p = 0.651). Environmental co-exposure of melamine and DEHP can potentially affect ACR in the community-dwelling Taiwanese adult population.

A novel 1,8-naphthalimide-based fluorescent chemosensor for the detection of HSA in living cells

Human serum albumin (HSA) is an essential protein for maintaining human health. Accurate detection and quantification of HSA are of great significance for disease diagnosis and biochemical research. Here, a new HSA fluorescent probe BNPE based on the 1,8-naphthalimide fluorophore was designed and synthesized. The probe could recognize HSA through a twisted intramolecular charge transfer mechanism, effectively avoid the interference of most substances, and realize HSA fluorescence imaging in living cells.

The impact of PM2.5 on kidney

PM2.5 poses a severe risk to kidneys, inducing kidney function decline, increasing the risk of suffering from chronic kidney diseases and promoting the occurrence and development of various renal tumors. The mechanism of PM2.5-induced renal injury may involve oxidative stress, inflammatory response, and cytotoxicity. This paper elaborated PM2.5-induced kidney damage and the corresponding possible mechanism so as to raise awareness of air pollution and reduce the damage to human body.

Sex-specific differences in early renal impairment associated with arsenic, lead, and cadmium exposure among young adults in Taiwan

Exposure to a single metal has been reported to damage renal function in humans. However, information regarding the association between multiple-metal exposure and markers for early renal impairment in different sexes among the young adult Taiwanese population is scarce. We assessed the association between exposure to arsenic (As), cadmium (Cd), and lead (Pb), and early renal impairment markers using urinary microalbumin (MA), β2-microglobulin (β2MG), and N-acetyl-beta-D-glucosaminidase (NAG) by analyzing 157 young adults aged 20‒29 years, in Taiwan. Inductively coupled plasma mass spectrometry was used to determine urinary As, Cd, and Pb levels. Regression models were applied to different sex groups. The results showed that after adjusting for potential confounding factors and each metal, urinary Cd levels were significantly positively associated with urinary MA (β = 0.523, 95% CI: 0.147-0.899) and β2MG (β = 1.502, 95% CI: 0.635-2.370) in males. However, the urinary Cd level was significantly positively associated with only urinary NAG (β = 0.161, 95% CI: 0.027-0.296) in females. This study thus indicates that the effect of exposure to metals (especially Cd) on early renal impairment among young adults in Taiwan is sex-specific. Our study results could contribute toward developing early intervention programs for decreasing the incidence of renal dysfunction. Further studies are warranted to confirm our findings and clarify the potential mechanisms involved.

Oxidative stress is associated with markers of renal dysfunction in children aged 6-9 years old in a South African population

INTRODUCTION

although studies have shown a relationship between albuminuria and oxidative stress in adults, limited information on the subject is available in children. The aim of this study was to assess the relationship between oxidative stress and albuminuria in South African children of African ancestry.

METHODS

a cross-sectional study involving 6-9 years old children in randomly selected rural and urban schools of the Eastern Cape Province of South Africa was conducted. Anthropometric measurements were done and urine samples were collected for the determination of titres of albumin, creatinine, 8-hydroxy-2-deoxy-guanosine (8-OHdG) and thiobarbituric acid reactive substances (TBARS). The urinary albumin to creatinine ratio (ACR) was calculated and used to determine albuminuria.

RESULTS

creatinine and 8-OHdG were significantly higher (p<0.05) in urban children than in rural children while albumin, ACR and TBARS were significantly higher (p<0.05) in rural compared to urban children. The prevalence of albuminuria was 14.05% of which microalbuminuria was 8.83% while macroalbuminuria was 5.22%. Albuminuria was higher in rural children than their urban counterparts and was more prevalent in females. TBARS was positively (p<0.05) associated with creatinine and albumin in the cohort as well as in females and urban children while 8-OHdG was positively associated with albumin in the cohort.

CONCLUSION

findings of this study showed that oxidative stress was associated with markers of renal dysfunction with a 14% prevalence of albuminuria observed in South African children of African ancestry.

The presence of simple renal cysts is associated with an increased risk of albuminuria in young adults

BACKGROUND/AIMS

The prevalence of simple renal cysts increases with age; however, they are occasionally found in adults aged < 40 years. This cross-sectional study evaluated the clinical significance of simple cysts in young adults, focusing on their associations with hematuria and albuminuria.

METHODS

Adults aged < 40 years who underwent comprehensive medical examination between January 2005 and December 2013 were included. Simple renal cysts were identified by ultrasonography.

RESULTS

Renal cysts were found in 276 of the 5,832 subjects (4.7%). Subjects with medullary sponge kidney (n = 1) or polycystic kidney disease (n = 5) were excluded. A single cyst and multiple cysts were found in 234 (4.0%) and 42 (0.7%) subjects, respectively. Age, high systolic blood pressure, and history of hypertension were independent risk factors for the presence of simple cysts. Simple cysts were not associated with an increased prevalence of hematuria. However, subjects with cysts showed a higher prevalence of albuminuria than those without (11.3% vs. 4.5%, p < 0.001). Multivariate analysis revealed that the existence of simple renal cysts was associated with a 2.30-fold increased prevalence of albuminuria (95% confidence interval, 1.512 to 3.519; p < 0.001) independent of other risk factors.

CONCLUSION

In young adults, the presence of simple renal cysts was independently associated with an increased prevalence of albuminuria. The causal relationship needs to be elucidated in further studies.

Blood DNA Methylation Predicts Diabetic Kidney Disease Progression in High Fat Diet-Fed Mice

Diabetic kidney disease (DKD) progresses at different rates among patients with type 2 diabetes mellitus (T2D). Early identification of patients with a higher risk of DKD progression is essential to improve prognosis. Epigenetic modifications, particularly DNA methylation, have been independently implicated in T2D and chronic kidney disease. The current study aimed to determine changes in blood DNA methylation that reflects and predicts DKD progression. C57BL/6 mice were fed a high-fat diet (HFD) from weaning and subclassified into two groups, HFD-1 and HFD-2, according to urinary kidney injury marker KIM-1/creatinine ratios (low vs. high) and histological abnormalities (mild–moderate vs. advanced). DNA methylation profiles were determined by reduced representative bisulfide sequencing (RRBS). Our results confirmed early and established DKD at week 9 and week 32, respectively. At week 32, advanced kidney injury was associated with dysregulation of methylation and demethylation enzymes in the kidney. Blood RRBS revealed 579 and 203 differentially methylated sites (DMS) between HFD-1 and HFD-2 animals at week 32 and week 9, respectively, among which 11 were common. The DMS in blood and kidney at week 32 were both related to organ development, neurogenesis, cell junction, and Wnt signalling, while the DMS in blood at week 9 suggested a specific enrichment of kidney development processes. In conclusion, our data strongly support the implication of early blood DNA methylation modifications and DKD progression in T2D that could be used to improve the disease’s prognostication.

Potential Role of N-Cadherin in Diagnosis and Prognosis of Diabetic Nephropathy

Diabetic nephropathy (DN) is a serious complication of diabetes affecting about half the people with diabetes and the leading cause of end stage renal disease (ESRD). Albuminuria and creatinine levels are currently the classic markers for the diagnosis of DN. However, many shortcomings are arising from the use of these markers mainly because they are not specific to DN and their levels are altered by multiple non-pathological factors. Therefore, the aim of this study is to identify better markers for the accurate and early diagnosis of DN. The study was performed on 159 subjects including 42 control subjects, 50 T2D without DN and 67 T2D subjects with DN. Our data show that circulating N-cadherin levels are significantly higher in the diabetic patients who are diagnosed with DN (842.6 ± 98.6 mg/l) compared to the diabetic patients who do not have DN (470.8 ± 111.5 mg/l) and the non-diabetic control group (412.6 ± 41.8 mg/l). We also report that this increase occurs early during the developmental stages of the disease since N-cadherin levels are significantly elevated in the microalbuminuric patients when compared to the healthy control group. In addition, we show a significant correlation between N-cadherin levels and renal markers including creatinine (in serum and urine), urea and eGFR in all the diabetic patients. In conclusion, our study presents N-cadherin as a novel marker for diabetic nephropathy that can be used as a valuable prognostic and diagnostic tool to slow down or even inhibit ESRD.

Cystatin C, renal resistance index, and kidney injury molecule-1 are potential early predictors of diabetic kidney disease in children with type 1 diabetes

BACKGROUND

Diabetic kidney disease (DKD) is the main cause of end-stage renal disease in patients with diabetes mellitus type I (DM-T1). Microalbuminuria and estimated glomerular filtration rate (eGFR) are standard predictors of DKD. However, these predictors have serious weaknesses. Our study aimed to analyze cystatin C, renal resistance index, and urinary kidney injury molecule-1 (KIM-1) as predictors of DKD.

METHODS

We conducted a cross-sectional study in 2019 on a consecutive sample of children and adolescents (10-18 years) diagnosed with DM-T1. The outcome was a risk for DKD estimated using standard predictors: age, urinary albumin, eGFR, serum creatinine, DM-T1 duration, HbA1c, blood pressure, and body mass index (BMI). We conducted the analysis using structural equation modeling.

RESULTS

We enrolled 75 children, 36 girls and 39 boys with the median interquartile range (IQR) age of 14 (11-16) years and a median (IQR) duration of DM-T1 of 6 (4-9) years. The three focal predictors (cystatin C, resistance index, and urinary KIM-1) were significantly associated with the estimated risk for DKD. Raw path coefficients for cystatin C were 3.16 [95% CI 0.78; 5.53; p = 0.009, false discovery rate (FDR) < 5%], for renal resistance index were -8.14 (95% CI -15.36; -0.92; p = 0.027; FDR < 5%), and for urinary KIM-1 were 0.47 (95% CI 0.02; 0.93; p = 0.040; FDR < 5%).

CONCLUSION

Cystatin C, renal resistance index, and KIM-1 may be associated with the risk for DKD in children and adolescents diagnosed with DM-T1. We encourage further prospective cohort studies to test our results.

Association between uric acid level and incidence of albuminuria in patients with type 2 diabetes mellitus: A 4.5-year cohort study

Using animal models and molecular biology researches, hyperuricemia has been shown to instruct renal arteriolopathy, arterial hypertension, and microvascular injury involving the renin-angiotensin system and resulting in renal function impairment. Nevertheless, the association between uric acid levels and the development of albuminuria has been under-investigated in patients with type 2 diabetes mellitus. Patients with type 2 diabetes and regular outpatient visits were recruited from the Puli Branch of the Taichung Veterans General Hospital in Taiwan since January 2014. Demographics, lifestyle features, and medical history were gathered by well-trained interviewers. All participants underwent comprehensive physical examinations, including a biochemical assay of venous blood specimens and urine samples after an 8-hour overnight fast. Participants were followed until June 2018. The primary outcome was the albuminuria incidence. Univariable and multivariable Cox regression analysis were employed to explore the relation between uric acid and incident albuminuria. Uric acid cutoffs for incident albuminuria were determined with the receiver operator characteristic curve. We included 247 qualified subjects (mean age: 64.78 years old [standard deviation = 11.29 years]; 138 [55.87%] men). During a 4.5-year follow-up duration, 20 subjects with incident albuminuria were recognized. Serum uric acid was significantly associated with an increased risk of incident albuminuria (adjusted hazard ratio = 2.39; 95% confidence interval: 1.53-3.75; P < .001) with potential confounders adjustment. The uric acid cutoff point was 6.9 mg/dL (area under the curve 0.708, sensitivity 60.0%, specificity 84.58%) for incident albuminuria. Serum uric acid was associated with incident albuminuria among patients with type 2 diabetes.

Risk of chronic kidney disease in women with a history of preterm delivery: Tehran Lipid and Glucose Study

BACKGROUND

Preterm delivery (PTD) may predict the risk of long-term maternal complications. Little is known about the association between preterm delivery and maternal risk of chronic kidney disease (CKD).This study aimed to explore whether a history of preterm delivery is associated with the risk of maternal CKD.

METHODS

In this population-based cohort study within the framework of the Tehran Lipid and Glucose Study (TLGS), a total of 3035 women with at least one delivery met our eligibility criteria. A time-dependent Cox proportional-hazards regression model was used to measure the hazard ratios (HRs) and 95% confidence intervals (CIs) for evaluating the association between history of preterm delivery and risk of CKD, adjusted for smoking, parity, age at first delivery, body mass index, educational level, preeclampsia, and gestational diabetes mellitus.

RESULTS

A total of 212 women with a history of at least one preterm delivery and 2823 women with term delivery were included. The median (interquartile range) follow-up in the preterm and term delivery groups was 16 (13.0-17.0) and 16 (14.0-17.0) years, respectively. The results of multivariate Cox regression model, adjusted for confounders, showed that the risk of CKD significantly increased by 46% in women with a history of preterm delivery. Moreover, according to the time-dependent Cox regression analysis, the risk of CKD in women with a history of preterm delivery was 2.68 (95% CI 1.02, 7.05, P = 0.04) fold higher than among those with no history of  preterm delivery.

CONCLUSION

Pregnancy if complicated by preterm delivery, may increase the risk of future maternal morbidities. Our findings suggest that a history of preterm delivery was associated with an increased maternal risk of CKD in the long term. Further longitudinal studies are needed to confirm our findings.

The gut microbiome in differential diagnosis of diabetic kidney disease and membranous nephropathy

Background

Diabetic kidney disease (DKD) and membranous nephropathy (MN) are the two major causes of end-stage renal disease (ESRD). Increasing evidence has shown that intestinal dysbiosis is associated with many diseases. The aim of this study was to explore the composition of the gut microbiome in DKD and MN patients.

Methods

16S rRNA gene sequencing was performed on 271 fecal samples (DKD = 129 and MN = 142), and taxonomic annotation of microbial composition and function was completed.

Results

We observed distinct microbial communities between the two groups, with MN samples exhibiting more severe dysbiosis than DKD samples. Relative increases in genera producing short-chain fatty acids (SCFAs) in DKD and a higher proportion of potential pathogens in MN were the main contributors to the microbiome alterations in the two groups. Five-fold cross-validation was performed on a random forest model, and four operational taxonomic unit (OTU)-based microbial markers were selected to distinguish DKD from MN. The results showed 92.42% accuracy in the training set and 94.52% accuracy in the testing set, indicating high potential for these microbiome-based markers in separating MN from DKD. Overexpression of several amino acid metabolic pathways, carbohydrate metabolism and lipid metabolism was found in DKD, while interconversion of pentose/glucoronate and membrane transport in relation to ABC transporters and the phosphotransferase system were increased in MN.

Conclusion

The composition of the gut microbiome appears to differ considerably between patients with DKD and those with MN. Thus, microbiome-based markers could be used as an alternative tool to distinguish DKD and MN.

Determination of certain urinary microRNAs as promising biomarkers in diabetic nephropathy patients using gold nanoparticles

Diabetic nephropathy (DN) is a major leading cause of kidney failure. So, early detection of DN by assessing urinary microRNAs (miRNAs) expression may be of clinical value. In this study, the diagnostic value of two urinary miRNAs (miR-210 & miR-34a) as biomarkers for diagnosis of DN was assessed using a simple colorimetric gold nanoparticle (AuNP) assay and real-time PCR. MiR-(210 & 34a) were markedly up-regulated in DN groups (micro-albuminuric and macro-albuminuric groups) compared to the non-albuminuric group and healthy controls. The sensitivity and specificity for the qualitative detection of urinary miR-(210 & 34a) using the AuNP assay were (78% and 72%) & (81% and 69%), respectively, which were consistent with the results of real-time PCR. There was a highly significant correlation between urinary miR-(210 & 34a) detected by either qRT-PCR or qualitative AuNP assay. Accordingly, this simple AuNP assay may be considered a valid test for the detection of these two urinary miRNAs as potential biomarkers that can aid in the noninvasive diagnosis of DN.

Urinary albumin-to-creatinine ratio is inversely related to nitric oxide synthesis in young black adults: the African-PREDICT study

Hypertension is common in black populations and is known to be associated with low nitric oxide (NO) bioavailability. We compared plasma and urinary NO-related markers and plasma creatine kinase (CK) levels between young healthy black and white adults along with the associations of these markers with the urinary albumin-to-creatinine ratio (uACR), which is a surrogate marker of endothelial and kidney function. We included 1105 participants (20-30 years). We measured the uACR, plasma CK, plasma and urinary arginine, homoarginine, asymmetric (ADMA) and symmetric dimethylarginine (SDMA), urinary ornithine/citrulline, nitrate and nitrite, and malondialdehyde (MDA). In addition, the urinary nitrate-to-nitrite ratio (U_NOxR) was calculated and used as a measure of circulating NO bioavailability. The uACR was comparable between the groups, yet the black group had lower urinary nitrate (by -15%) and U_NOxR values (by -18%) (both p ≤ 0.001), higher plasma (by +9.6%) and urinary (by +5.9%) arginine (both p ≤ 0.004), higher plasma (by +13%) and urinary (by +3.7%) ADMA (both p ≤ 0.033), and higher CK (by +9.5%) and MDA (by +19%) (both p < 0.001) compared with white adults. Plasma and urinary homoarginine were similar between the groups. In the multiple regression analysis, we confirmed the inverse associations of the uACR with both plasma (adj. R² = 0.066; β = -0.209; p = 0.005) and urinary (adj. R² = 0.066; β = -0.149; p = 0.010) homoarginine and with the U_NOxR (adj. R² = 0.060; β = -0.122; p = 0.031) in the black group only. The overall less favorable NO profile and higher CK and MDA levels in the black cohort along with the adverse associations with the uACR may reflect the vulnerability of this cohort to the early development of hypertension.

The prevalence of chronic kidney disease in Iceland according to KDIGO criteria and age-adapted estimated glomerular filtration rate thresholds

Most epidemiological studies on chronic kidney disease (CKD) are based solely on estimated glomerular filtration rate (eGFR). Few studies have included proteinuria, while the chronicity criterion is usually omitted. To explore this, we examined the prevalence of CKD stages 1-5 in Iceland based on multiple markers of kidney damage. All serum creatinine values, urine protein measurements and diagnostic codes for kidney diseases and comorbid conditions for people aged 18 years and older were obtained from electronic medical records of all healthcare institutions in Iceland in 2008-2016. CKD was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guideline using diagnoses indicative of a chronic kidney disease, proteinuria and/or an eGFR under 60 mL/min/1.73 m² for over three months. Mean annual age-standardized prevalence of CKD stages 1-5 was calculated based on the KDIGO criteria and age-adapted eGFR thresholds from 2,120,147 creatinine values for 218,437 individuals, 306,531 proteinuria measurements for 86,364 individuals and 6973 individuals carrying a kidney disease diagnosis. Median age was 63 years (range, 18-106) and 47% were male. The mean annual age standardized CKD prevalence was 5.13% for men and 6.75% for women using the KDIGO criteria but by age-adapted eGFR cut-offs, the prevalence was 3.27% for men and 4.01% for women. Thus, our nationwide study, defining CKD in Iceland with strict adherence to the KDIGO criteria, demonstrates a lower prevalence of CKD than anticipated from most previous studies.

Accelerated podocyte detachment early after kidney transplantation is related to long-term allograft loss of function

BACKGROUND

Kidney allograft half-life has not improved despite excellent short-term survival. Recent long-term surveillance biopsy studies identify accumulating glomerulosclerosis (GS) to be associated with late allograft loss. While podocyte depletion is well known to drive proteinuria and GS in animal models and human glomerular diseases, its role in renal allograft loss of function is generally not recognized.

METHODS

To address these questions, we collected urine from 125 kidney allograft recipients in the first posttransplant year for urine pellet messenger RNA (mRNA) and protein analysis, with a median follow up of 4.5 years.

RESULTS

Using multivariable linear models adjusted for proteinuria, transplant, recipient and donor factors, we observed that the average urine pellet podocin mRNA normalized to urine creatinine (UPodCR) in the first posttransplant year was significantly associated with an estimated glomerular filtration rate (eGFR) decline (P = 0.001). The relationship between UPodCR and eGFR decline persisted even among recipients who were nonproteinuric and who had no recurrent or de novo glomerular disease identified on 1-year protocol biopsy. Finally, we identified recipient, donor and recipient:donor body surface area mismatch ratio to be independently associated with UPodCR early after transplantation. A larger donor was protective, while a larger recipient and increased recipient:donor size mismatch ratio were associated with increased UPodCR.

CONCLUSIONS

These findings support the concept that in kidney allografts, accelerated podocyte loss precedes proteinuria and is associated with inferior long-term allograft outcomes as measured by eGFR decline and may be initiated by recipient:donor size mismatch. Modulating factors driving early podocyte detachment after kidney transplantation may help improve long-term outcomes.

Relationship between Microalbuminuria and Disease Activity in Patients with Ulcerative Colitis

BACKGROUND

Introducing a non-invasive method for determining disease activity is important in patients with ulcerative colitis (UC). So in this study, we aimed to assess the association between disease activity index and microalbuminuria in patients with UC.

METHODS

In the present cross-sectional study, 84 patients with UC were selected. The disease activity was calculated by the partial Mayo clinic score. Microalbuminuria was assessed using the immunoturbidimetric method in a first-voided sample in the morning in two consecutive days and the mean of these two measurements was reported as urinary microalbumin level. Serum C reactive protein (CRP), erythrocyte sedimentation rate (ESR), and fecal calprotectin were measured respectively using conventional turbidimetric immunoassay, Westergren method, and ELISA methods.

RESULTS

The mean age of the participants was 40.01 ± 12.85 years, 60.8% of them were female and 53.5% had microalbuminuria. The frequency of microalbuminuria was significantly higher in patients with active compared with inactive inflammatory bowel disease (IBD). There were significant differences between the patients with active and inactive disease regarding CRP, ESR, and calprotectin (p < 0.001). Moreover, there was a strong correlation between microalbuminuria and CRP (r = 0.89, p < 0.001), ESR (r = 0.92, p < 0.001), and calprotectin (r = 0.91, p < 0.001).

CONCLUSION

Microalbuminuria could be used as a non-invasive marker of disease activity in patients with UC.

Alpha1-Antitrypsin in Urinary Extracellular Vesicles: A Potential Biomarker of Diabetic Kidney Disease Prior to Microalbuminuria

PURPOSE

Diabetic kidney disease (DKD), which is related to inflammation and immune response, is the primary vascular complication of diabetes mellitus and also the leading etiology of end-stage renal disease. Urinary extracellular vesicles (UEVs) are an attractive source for biomarker detection as they involve molecular constituents derived from their parental sections of the nephron. In this study, we aimed to search for a potential biomarker in UEVs for the early diagnosis and prediction of DKD, especially before the emergence of microalbuminuria.

PATIENTS AND METHODS

UEVs were isolated from the urine of healthy subjects, pre-diabetic, and diabetic patients with varying degrees of kidney damage by ultracentrifugation, and the extracted UEVs were used to measure alpha1-antitrypsin (α1-AT) by Western blot. To explore the function of α1-AT in the inflammatory process leading to DKD, we silenced the expression of α1-AT in renal tubular epithelial cells using cell transfection techniques to assess the differential expression of the inflammatory factors such as MCP-1 and TNF-α using qRT-PCR.

RESULTS

There was no expression of α1-AT in the UEVs of either healthy or pre-diabetic subjects. Its expression was significantly increased in the UEVs of diabetic patients with normoalbuminuria (prior to microalbuminuria), which was more sensitive and more stable than other renal indexes to predict DKD. Additionally, the expression of α1-AT in UEVs was gradually upregulated with the aggravation of DKD and the decline of renal function. In vitro, the mRNA expression of MCP-1 and TNF-α was significantly decreased when the generation of α1-AT in tubular epithelial cells was inhibited under high glucose stimulation.

CONCLUSION

Our results suggest that α1-AT derived from UEVs, especially in diabetic patients with normoalbuminuria, might serve as a potential noninvasive biomarker for diagnosis of DKD early in the development of the disease and may predict the future decline of renal function.

Accuracy Evaluation of a Tetrabromophenolphthalein Ethyl Ester Colorimetric Assay for Urinary Albumin

BACKGROUND

The tetrabromophenolphthalein ethyl ester (TBPE) assay has been used to quantify urinary albumin in point-of-care devices. We assessed the accuracy of this TBPE assay for urinary albumin through comparison with an established immunoturbidimetric method (ADVIA 1800 Chemistry System, Siemens).

METHODS

We developed a TBPE assay protocol to quantify albumin in the range associated with microalbuminuria (0-200 mg/L). The Jaffe reaction and a 3-dimensional (3D) surface were used to compensate for creatinine interference. Spiked simulated urine samples and patient samples were used to compare the TBPE assay with the immunoturbidimetric method. Multiple linear regression was used to analyze factors that could account for discrepancies between the 2 methods.

RESULTS

We found that creatinine interfered with the TBPE assay. To compensate, a 3D surface was successfully used to quantify albumin in spiked deionized water and simulated urine samples. In spiked simulated urine samples, the immunoturbidimetric method underestimated the albumin concentration by 2 to 45 mg/L, and the TBPE assay overestimated it by 9 to 82 mg/L. In patient samples, the albumin concentrations measured with the TBPE assay and the immunoturbidimetric method differed by an average of 184 mg/L.

CONCLUSIONS

The TBPE assay is a function of the creatinine concentration, and a 3D surface can be used to provide accurate albumin concentrations for standard samples. The corrected TBPE method and the immunoturbidimetric method deviated from known concentrations of spiked samples. Further investigation and comparisons with a third albumin measurement method, such as LC-MS/MS, are necessary before conclusions on the accuracy of the TBPE assay can be made.

Utility of urinary liver-type fatty acid-binding protein as a predictor of renal dysfunction in Japanese patients with HIV receiving tenofovir disoproxil fumarate with low urinary β2 microglobulin levels: a retrospective observational study

Background

Tenofovir disoproxil fumarate (TDF) is known to reduce estimated glomerular filtration rate (eGFR). It is clinically important to identify patients at high risk for renal dysfunction as early as possible. Among the tubular markers, urinary β2 microglobulin (Uβ2MG) is a well-known biomarker of TDF-related tubulopathy. However, renal dysfunction has often been occurred in patients receiving TDF with low Uβ2MG levels. Recently, urinary liver-type fatty acid–binding protein (UL-FABP) was suggested to be predictor of the progression of renal dysfunction. Thus, we focused on UL-FABP in patients receiving TDF with low Uβ2MG levels.

Methods

A retrospective, observational, single-center study, between January 2013 and December 2016, was conducted. Two renal end points (> 25% decrement in eGFR and > 20 mL/min/1.73 m² decrement relative to the baseline) were assessed. To estimate the effect of UL-FABP on time to the first event, log-rank test was performed.

Results

A total of 24 Japanese outpatients with human immunodeficiency virus receiving TDF were enrolled. The outcome each occurred in two patients during the follow-up period. UL-FABP levels ≥4.0 μg/g creatinine was significantly associated with > 25% decrement and > 20 mL/min/1.73 m² decrement (p = 0.006 and 0.001, respectively).

Conclusion

Based on our preliminary analysis, UL-FABP levels ≥4.0 μg/g creatinine predict renal dysfunction in patients receiving TDF with low Uβ2MG levels.

Serum leptin in diabetic nephropathy male patients from Gaza Strip

OBJECTIVE

To assess serum leptin in diabetic nephropathy male patients from Gaza Strip.

MATERIALS AND METHODS

This case-control study comprised 132 type 2 diabetic patients and 44 non-diabetic controls. The diabetic patients were classified into three groups; 44 normoalbuminurics, 44 microalbuminurics and 44 macroalbuminurics. Data were obtained from questionnaire interview, and biochemical analysis of blood and urine samples. Patients and controls were matched for age and body mass index (BMI).

RESULTS

Serum leptin was significantly higher in micro- and macro-albuminuric patients (14.6 ± 11.7 and 15.6 ± 13.5 ng/ml) than controls and normoalbuminurics (5.9 ± 4.0 and 8.1 ± 7.6 ng/ml) with P < 0.05. In general, serum glucose, urea, createnine, cholesterol, triglycerides, low density lipoprotein cholesterol (LDL-C), urinary albumin and albumin creatinine ratio (ACR) were increased in diabetic groups compared to non-diabetics, and reaching their maximum increase in macroalbuminurics whereas high density lipoprotein cholesterol (HDL-C), urinary creatinine and glomerular filtration rate (GFR) were decreased reaching its maximum decrease in macroalbuminurics. Serum leptin showed significant positive correlations with diabetes duration (r = 0.188, P = 0.020), glucose (r = 0.298, P < 0.001), cholesterol (r = 0.323, P < 0.001), triglycerides (r = 0.361, P < 0.001), LDL-C (r = 0.248, P = 0.001) and urinary albumin (r = 0.256, P = 0.001) whereas negative significant correlations were found with HDL-C (r = -0.313, P < 0.001) and urinary creatinine (r = -0.202, P = 0.007).

CONCLUSION

The comitant raise of serum leptin with urinary albumin combined with decrease in GFR makes leptin eligible candidate as a biomarker for progression towards diabetic nephropathy in type 2 diabetes.

Multiparametric assessment of renal physiology in healthy volunteers using noninvasive magnetic resonance imaging

Noninvasive methods of magnetic resonance imaging (MRI) can quantify parameters of kidney function. The main purpose of this study was to determine baseline values of such parameters in healthy volunteers. In 28 healthy volunteers (15 women and 13 men), arterial spin labeling to estimate regional renal perfusion, blood oxygen level-dependent transverse relaxation rate (R₂*) to estimate oxygenation, and apparent diffusion coefficient (ADC), true diffusion (D), and longitudinal relaxation time (T₁) to estimate tissue properties were determined bilaterally in the cortex and outer and inner medulla. Additionally, phase-contrast MRI was applied in the renal arteries to quantify total renal blood flow. The results demonstrated profound gradients of perfusion, ADC, and D with highest values in the kidney cortex and a decrease towards the inner medulla. R₂* and T₁ were lowest in kidney cortex and increased towards the inner medulla. Total renal blood flow correlated with body surface area, body mass index, and renal volume. Similar patterns in all investigated parameters were observed in women and men. In conclusion, noninvasive MRI provides useful tools to evaluate intrarenal differences in blood flow, perfusion, diffusion, oxygenation, and structural properties of the kidney tissue. As such, this experimental approach has the potential to advance our present understanding regarding normal physiology and the pathological processes associated with acute and chronic kidney disease.

Electrochemical immunosensor utilizing electrodeposited Au nanocrystals and dielectrophoretically trapped PS/Ag/ab-HSA nanoprobes for detection of microalbuminuria at point of care

In this study, we have fabricated a simple disposable electrochemical immunosensor for the point of care testing of microalbuminuria, a well-known clinical biomarker for the onset of chronic kidney disease. The immunosensor is fabricated by screen-printing carbon interdigitated microelectrodes on a flexible plastic substrate and utilizes electrochemical impedance spectroscopy to enable direct and label free immunosensing by analyzing interfacial changes on the electrode surface. To improve conductivity and biocompatibility of the screen-printed electrodes, we have modified it with gold nanoparticles, which are electrodeposited using linear sweep voltammetry. To enable efficient immobilization of HSA antibodies, we have developed novel PS/Ag/ab-HSA nanoprobes (polystyrene nanoparticle core with silver nanoshells covalently conjugated to HSA antibodies), and these nanoprobes are trapped on the electrode surface using dielectrophoresis. Each immunosensor has two sensing sites corresponding to test and control to improve specificity by performing differential analysis. Immunosensing results show that the normalized impedance response is linearly dependent on albumin concentration in the clinically relevant range with good repeatability. We have also developed a portable impedance readout module that can analyze the data obtained from the immunosensor and transmit it wirelessly for cloud computing. Consequently, the developed immunosensing platform can be extended to the detection of a range of immunoreactions and shows promise for point of diagnosis and public healthcare monitoring.

Associations between Body Mass Index and Chronic Kidney Disease in Type 2 Diabetes Mellitus Patients: Findings from the Northeast of Thailand

BACKGROUND

Chronic kidney disease (CKD) has emerged as a public health burden globally. Obesity and long-term hyperglycaemia can initiate the renal vascular complications in patients with type 2 diabetes mellitus (T2DM). This study aimed to investigate the association of body mass index (BMI) with the CKD in patients with T2DM.

METHODS

This study has used retrospective medical records, biochemical reports, and anthropometric measurements of 3,580 T2DM patients which were collected between January to December 2015 from a district hospital in Thailand. CKD was defined according to the measurement of estimated glomerular filtration rate (<60 mL/min/1.73 m²). Multiple logistic regression analysis was used to explore the association between BMI and CKD in patients with T2DM.

RESULTS

The mean age of the participants was 60.86±9.67 years, 53.68% had poor glycaemic control, and 45.21% were overweight. About one-in-four (23.26%) T2DM patients had CKD. The mean BMI of non-CKD group was slightly higher (25.30 kg/m² vs. 24.30 kg/m²) when compared with CKD patients. Multivariable analysis showed that older age, female sex, hypertension, and microalbuminuria were associated with the presence of CKD. No association was observed between CKD and poorly controlled glycosylated hemoglobin or hypercholesterolemia. Adjusted analysis further showed overweight and obesity were negatively associated with CKD (adjusted odds ratio [AOR], 0.73; 95% confidence interval [CI], 0.58 to 0.93) and (AOR, 0.53; 95% CI, 0.35 to 0.81), respectively.

CONCLUSION

The negative association of BMI with CKD could reflect the reverse causality. Lower BMI might not lead a diabetic patient to develop CKD, but there are possibilities that CKD leads the patient to experience reduced BMI.

YKL-40: A biomarker for early nephropathy in type 2 diabetic patients and its association with inflammatory cytokines

Diabetic Nephropathy (DN) is an important cause of morbidity and death amongst diabetes. Persistent micro and macroalbuminuria are well known predictors of DN leading to progressive end-stage renal disease. However, albuminuria has several limitations. Increasing evidences show that YKL-40 is highly expressed in variety of inflammatory diseases and also recognized as a non-invasive prognostic biomarker for inflammation. In the present study, we measured plasma YKL-40 levels in different stages of albuminuria and assessed its diagnostic accuracy as a biomarker for DN and correlated with different families of circulatory cytokines. A total of 306 subjects were recruited and divided into three groups [Group-I, control (n = 83), Group-II, Normoalbuminuria (n = 81), Group-III, DN (n = 142)]. Group-III is further subdivided into: Group-IIIa, microalbuminuria (n = 73), Group-IIIb, macroalbuminuria (n = 69). The median levels of YKL-40 (p = 0.001) showed a marked stepwise increase from normo to macroalbuminuria and positively correlated with eGFR. The AUC_ROC for YKL-40 was found to be high [0.95; (95% CI: 0.88-1.0)], when compared to other acute phase markers. Plasma YKL-40 showed a positive correlation with LIGHT/TNFSF14, sIL-6Ra, gp130/sIL-6Rβ, IFN-β, IL-8, TNFSF14, sCD-30 and eGFR meanwhile a negative correlation with TWEAK/TNFSF12, IL-7 like cytokine and IFN-λ2. Plasma YKL-40 could be a potential biomarker for early diagnosis of incipient DN among South Indian population.

Identification of candidate microRNA biomarkers in diabetic nephropathy: a meta-analysis of profiling studies

AIMS

The aim was to perform a meta-analysis on the miRNA expression profiling studies in diabetic nephropathy (DN) to identify candidate diagnostic biomarkers.

METHODS

A comprehensive literature search was done in several databases and 53 DN miRNA expression studies were selected. To identify significant DN-miR meta-signatures, two meta-analysis methods were employed: vote-counting strategy and the robust rank aggregation method. The targets of DN-miRs were obtained and a gene set enrichment analysis was carried out to identify the pathways most strongly affected by dysregulation of these miRNAs.

RESULTS

We identified a significant miRNA meta-signature common to both meta-analysis approaches of three up-regulated (miR-21-5p, miR-146a-5p, miR-10a-5p) and two down-regulated (miR-25-3p and miR-26a-5p) miRNAs. Besides that, subgroup analyses divided and compared the differentially expressed miRNAs according to species (human and animal), types of diabetes (T1DN and T2DN) and tissue types (kidney, blood and urine). Enrichment analysis confirmed that DN-miRs supportively target functionally related genes in signaling and community pathways in DN.

CONCLUSION

Five highly significant and consistently dysregulated miRNAs were identified, and future studies should focus on discovering their potential effect on DN and their clinical value as DN biomarkers and therapeutic mediators.

Peripheral blood mitochondrial DNA copy number as a novel potential biomarker for diabetic nephropathy in type 2 diabetes patients

The mitochondrial DNA copy number (mtDNA-CN) is a surrogate measure of mitochondrial function and altered mtDNA-CN reflects the oxidant-induced cell damage. A previous study by our group demonstrated that a reduction in the renal mtDNA-CN is implicated in the pathogenesis of diabetic nephropathy (DN), a leading cause of end-stage renal disease in diabetic patients. In the present study, it was investigated whether the mtDNA-CN in the peripheral blood may be utilized as a biomarker for DN in type 2 diabetes (T2D) patients. The study included 50 non-diabetic and 100 diabetic subjects. The diabetic subjects were sub-divided based on their albumin-to-creatinine ratio (ACR) into T2D patients with normoalbuminuria (n=50), DN patients with microalbuminuria (n=29) and DN patients with macroalbuminuria (n=21). The mtDNA-CN was measured in the peripheral blood by real-time polymerase chain reaction analysis. Patients with DN had a lower mtDNA-CN than patients with T2D and healthy controls (P<0.05). A sub-group analysis with stratification by the ACR indicated that a decreased mtDNA-CN was associated with the severity and the presence of DN, as it was lower in DN patients with macroalbuminuria than in DN patients with microalbuminuria and T2D patients with normoalbuminuria (P<0.01). The area under the receiver operating characteristic curve (AUC) for mtDNA-CN was 0.916 (sensitivity, 86% and specificity, 74%) and 0.961 (sensitivity, 96% and specificity, 88%) for differentiating DN patients from T2D patients without DN and from healthy controls, respectively. Furthermore, the AUC of mtDNA-CN for differentiating DN patients with microalbuminuria from those with macroalbuminuria was 0.895 (sensitivity, 83% and specificity, 85%). Multivariate analysis revealed that the mtDNA-CN was significantly associated with the occurrence and progression of DN, even after adjustment for age, mean blood pressure, glycated haemoglobin A1c and total cholesterol (P<0.05). In patients with DN, a decreased mtDNA-CN was negatively correlated with albuminuria and conventional risk factors for DN, and was positively correlated with the estimated glomerular filtration rate. The present results therefore suggest the utilization of circulating mtDNA-CN as a novel biomarker for the early diagnosis of DN and indicate the significance of decreased mtDNA-CN as another independent risk factor for DN.

Association between Bone Mineral Density and Albuminuria: Cross-Sectional Analysis of Data from the 2011 Korea National Health and Nutrition Examination Survey V-2

BACKGROUND

Albuminuria is known to be independently associated with progression of renal and cardiovascular disease. However, little is known regarding the exact relationship between albuminuria and bone mineral density (BMD). The aim of this population-based study conducted in Korea was to identify the association between albuminuria and BMD.

METHODS

We performed a cross-sectional analysis of data from the Korea National Health and Nutrition Examination Survey (KNHANES V-2) 2011. BMD was measured for total hip (TH), femur neck (FN), and lumbar spine (LS). Analysis of covariance was used to compare BMD levels between the groups at the TH, FN, and LS sites, after adjusting for age. Separate analyses were performed according to sex; women were divided into two groups according to menopausal status and each group was subdivided into three according to urine albumin-to-creatinine ratio (level 1, <30 mg/g; level 2, 30 to 299 mg/g; level 3, ≥300 mg/g).

RESULTS

Data on a total of 1,831 adults (857 men and 974 women) were analyzed. In postmenopausal women, after adjusting for age, BMD of TH tended to decrease as levels of albuminuria increased (0.767±0.117, 0.757±0.129, 0.752±0.118, respectively; P=0.040). However, there was no significant difference in BMD according to albuminuria level in premenopausal women and men.

CONCLUSION

Level of albuminuria was closely related with BMD of TH in postmenopausal women, after adjusting for age, but there was no significant relationship between albuminuria and BMD in premenopausal women and men.

Expression of microRNA‑377 and microRNA‑192 and their potential as blood‑based biomarkers for early detection of type 2 diabetic nephropathy

The increased incidence of diabetic nephropathy (DN) in type 2 diabetes (T2D) requires novel markers for the early detection of DN. Previously, microRNAs (miRs) have been demonstrated to be promising disease biomarkers. The present study evaluated the biomarker potential of DN‑associated miR‑377 and miR‑192 in the early stages of DN. The study included 85 participants: 55 patients with T2D (30 without DN and 25 with DN) and 30 healthy controls. The patients with T2D were classified according to albumin‑to‑creatinine ratio and were split into three groups: Normoalbuminuric group (n=30), microalbuminuric group (n=15) and macroalbuminuric group (n=10). Reverse transcription‑quantitative polymerase chain reaction analysis was used to evaluate blood miR expression. It was observed that there was higher miR‑377 expression and lower miR‑192 expression in T2D patients with and without DN compared with healthy controls (P<0.05). miR‑377 was higher in the normoalbuminuric group and gradually increased in the microalbuminuric and macroalbuminuric groups (P<0.05), whereas miR‑192 was lower in the macroalbuminuric group compared with the normoalbuminuric group (P<0.05). Regression analysis revealed direct associations between the two miRs and albuminuria (P<0.05). miR‑377 was independently associated with DN risk, even following multivariable adjustment, and albuminuria was the only predictor of miR‑377 (P<0.001). In discriminating overall patients from healthy subjects, ROC analysis revealed areas under the curve (AUCs) of 0.851 for miR377 and 0.774 for miR‑192 (P<0.001). In discriminating the normoalbuminuric group from the microalbuminuric/macroalbuminuric groups, the AUCs were 0.711 (P=0.008) and 0.70 (P=0.049) for miR‑377 and miR‑192, respectively. In patients with microalbuminuria and macroalbuminuria, miR‑377 correlated positively with albuminuria and negatively with renal function, whereas miR‑192 correlated negatively with albuminuria and positively with renal function (P=0.001), and the two miRs were correlated with known risk factors of DN (P<0.05). The results suggested that blood‑based miR‑377 and miR‑192 may serve as potential biomarkers for early detection of DN. Further validation studies are required with larger sample sizes.

Early renal damage among children living in the region of highest burden of chronic kidney disease of unknown etiology (CKDu) in Sri Lanka

Background

Chronic kidney disease of unknown origin (CKDu) in Sri Lanka is grouped with several other epidemics of similar nature across the world as Chronic Interstitial Nephritis in Agricultural Communities (CINAC). In CKDu endemic countries, the focus has mainly been on adults. We hypothesized that studying distribution and factors associated with elevated urine albumin to creatinine ratio (UACR), an early marker of kidney injury, among children living in a CKDu endemic area may provide important clues about the onset and progression of the disease.

Methods

This cross sectional study was performed in rural primary schools in North Central Province of Sri Lnaka, a CKDu high endemic region. Total of 2880 students aging 5 to 11 years from 67 schools were enrolled for urinalysis in a random spot urine sample. Bedside Schwartz formula was used to measure estimated glomerular filtration rate (eGFR) on all children with UACR > 30 mg/g in Polonnaruwa district and a group of age matched controls. A standard multiple linear regression using log transformed UACR as the dependent variable was performed. Mean eGFR were compared between UACR elevated group and controls using independent sample t test.

Results

Median UACR was 10.3 mg/g. Sex, ethnicity, history of having a chronic disease and age uniquely contributed to the multiple regression model which only explained 2.8% of the variance in the log of the UACR (p < 0.001). Only 15 (0.5%) had UACR> 300 mg/g while 8.2% (n = 236) had UACR between 30 to 300 mg/g and 89.8% (n = 203) of them did not have a chronic disease (Chi square 2.21, p = 0.091). Mean eGFR was significantly lower in the group with elevated UACR (88.9 mg/dl/1.73 m2, 95% CI for mean 86.4- 91.3) compared to group with normal UACR (93.7 mg/dl/1.73 m2,95% CI 91.1- 96.3) (t 2.7, p 0.007). Three out of the four students with eGFR less than 60 mg/dl/1.73 m2 had moderately elevated UACR.

Conclusion

This study provides evidence to suggest that children in CKDu endemic regions are having an early renal damage. This observation needs to be investigated further in order to understand the worldwide epidemic of CKDu.

Urinary type IV collagen excretion is involved in the decline in estimated glomerular filtration rate in the Japanese general population without diabetes: A 5-year observational study

Urinary type IV collagen (U-Col4) and albumin excretion is evaluated to monitor the development of diabetic kidney disease. However, U-Col4 excretion in the general population without diabetes has not yet been fully elucidated. In this study, 1067 participants without diabetes and with urinary albumin-creatinine ratio <300 mg/gCr (normo- or microalbuminuria) who underwent an annual health examination in 2004 were enrolled and observed for 5 years. They were divided according to the amount of U-Col4 or urinary albumin excreted. The decline in estimated glomerular filtration rate (eGFR) was calculated. In participants with eGFR ≥80 mL/min, abnormal U-Col4 excretion was indicated as a significant independent risk factor for 10% eGFR change per year, which is one of the prognostic factors for the development of end-stage kidney disease. Moreover, in contrast to urinary albumin excretion, U-Col4 excretion was not related to age or kidney function, suggesting that some individuals with abnormal U-Col4 excretion can have an independent hidden risk for the development of kidney dysfunction. In conclusion, it is important to measure U-Col4 excretion in the general population without diabetes to determine changes in renal features in every individual and help detect future complications such as diabetic kidney disease. If U-Col4 excretion is abnormal, kidney manifestation should be carefully followed up, even if the kidney function and urinalysis findings are normal.

Associations between microalbuminuria and parameters of flow-mediated vasodilatation obtained by continuous measurement approaches

The associations between microalbuminuria and various parameters of flow-mediated vasodilatation (FMD) are not completely understood. We retrospectively analyzed 265 consecutive patients who underwent coronary angiography and in whom we could measure FMD and the urine albumin-creatinine ratio (UACR). Using 15 continuous measurement approaches, we measured FMD as the magnitude of the percentage change in the brachial artery diameter from baseline to peak (bFMD), the maximum FMD rate calculated as the maximal slope of dilation (FMD-MDR), and the integrated FMD response calculated as the area under the dilation curve during the 60- and 120-s dilation periods (FMD-AUC60 and FMD-AUC120). We divided the patients into two groups according to UACR: normoalbuminuria (NOR, n = 211) and microalbuminuria (MIC, n = 54). The MIC group showed a significantly higher percentage of coronary artery disease than the NOR group. FMD-AUC60 and FMD-AUC120, but not FMD-MDR, in the MIC group were significantly lower than those in the NOR group. On the other hand, bFMD in the MIC group tended to be lower than that in the NOR group, but this difference was not significant. A multiple regression analysis indicated that FMD-AUC120 and diabetes mellitus were predictors of MIC. Finally, we defined the cut-off value of FMD-AUC₁₂₀ for the presence of MIC in all patients as 8.4 mm x second (sensitivity 0.640, specificity 0.588) by a receiver-operating characteristic curve analysis. In conclusion, this study provides more definitive evidence for the association of microalbuminuria with endothelial dysfunction. FMD-AUC120 may be a superior marker for MIC.

Effects of chronic fructose overload on renal dopaminergic system: alteration of urinary L-dopa/dopamine index correlates to hypertension and precedes kidney structural damage

Insulin resistance induced by a high-fructose diet has been associated to hypertension and renal damage. The aim of this work was to assess alterations in the urinary L-dopa/dopamine ratio over three time periods in rats with insulin resistance induced by fructose overload and its correlation with blood pressure levels and the presence of microalbuminuria and reduced nephrin expression as markers of renal structural damage. Male Sprague-Dawley rats were randomly divided into six groups: control (C) (C4, C8 and C12) with tap water to drink and fructose-overloaded (FO) rats (FO4, FO8 and FO12) with a fructose solution (10% w/v) to drink for 4, 8 and 12 weeks. A significant increase of the urinary L-dopa/dopamine ratio was found in FO rats since week 4, which positively correlated to the development of hypertension and preceded in time the onset of microalbuminuria and reduced nephrin expression observed on week 12 of treatment. The alteration of this ratio was associated to an impairment of the renal dopaminergic system, evidenced by a reduction in renal dopamine transporters and dopamine D1 receptor expression, leading to an overexpression and overactivation of the enzyme Na⁺, K⁺-ATPase with sodium retention. In conclusion, urinary L-dopa/dopamine ratio alteration in rats with fructose overload positively correlated to the development of hypertension and preceded in time the onset of renal structural damage. This is the first study to propose the use of the urinary L-dopa/dopamine index as marker of renal dysfunction that temporarily precedes kidney structural damage induced by fructose overload.

Why overestimate or underestimate chronic kidney disease when correct estimation is possible?

There is no doubt that the introduction of the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines 14 years ago, and their subsequent updates, have substantially contributed to the early detection of different stages of chronic kidney disease (CKD). Several recent studies from different parts of the world mention a CKD prevalence of 8-13%. However, some editorials and reviews have begun to describe the weaknesses of a substantial number of studies. Maremar (maladies rénales chroniques au Maroc) is a recently published prevalence study of CKD, hypertension, diabetes and obesity in a randomized, representative and high response rate (85%) sample of the adult population of Morocco that strictly applied the KDIGO guidelines. When adjusted to the actual adult population of Morocco (2015), a rather low prevalence of CKD (2.9%) was found. Several reasons for this low prevalence were identified; the tagine-like population pyramid of the Maremar population was a factor, but even more important were the confirmation of proteinuria found at first screening and the proof of chronicity of decreased estimated glomerular filtration rate (eGFR), eliminating false positive results. In addition, it was found that when an arbitrary single threshold of eGFR (<60 mL/min/1.73 m2) was used to classify CKD stages 3, 4 and 5, it lead to substantial 'overdiagnosis' (false positives) in the elderly (>55 years of age), particularly in those without proteinuria, haematuria or hypertension. It also resulted in a significant 'underdiagnosis' (false negatives) in younger individuals with an eGFR >60 mL/min/1.73 m2 and below the third percentile of their age-/gender-category. The use of the third percentile eGFR level as a cut-off, based on age-gender-specific reference values of eGFR, allows the detection of these false positives and negatives. There is an urgent need for additional quality studies of the prevalence of CKD using the recent KDIGO guidelines in the correct way, to avoid overestimation of the true disease state of CKD by ≥50% with potentially dramatic consequences.

Risk assessment of environmental exposure to heavy metals in mothers and their respective infants

Exposure to heavy metals can cause renal injury, which has been well documented in occupational exposure. Studies of low exposure in the general population, however, are still scarce, particularly for vulnerable populations such as mothers and young children. This study evaluated exposure to heavy metals, and biomarkers of renal function and oxidative stress in 944 lactating mothers and their infants and investigated the role of the interaction between heavy metals and oxidative stress in altering renal function. Mother and infant urine samples were analyzed to measure mercury (Hg), cadmium (Cd), and lead (Pb) concentrations for determining body-burden exposure; N-acetyl-β-d-glucosaminidase (NAG), α₁-microglobulin (α₁-MG), albumin (ALB), and creatinine (Cr) concentrations for determining early renal injury; and 8-hydroxy-2-deoxyguanosine (8-OHdG) and malondialdehyde (MDA) concentrations for determining oxidative stress. The median concentrclearlyations in mothers presented as μg/g Cr (infants as μg/l) for Hg, Cd, and Pb were 0.695 (0.716), 0.322 (0.343), and 3.97 (5.306) respectively. The mothers and their infants had clearly been exposed to heavy metals and had levels higher than the reference values reported for the general populations of USA, Germany, and Canada. Multiple regression analyses clearly demonstrated associations between urinary heavy metals in quartiles and several renal and oxidative biomarkers in mothers and to a lesser extent their infants. ß coefficients for urinary excretions of MDA, 8-OHdG, ALB, α₁-MG, NAG, and Cr in mothers were high in the highest quartile of Hg (1.183-51.29μg/g Cr or 1.732-106.95μg/l), Cd (0.565-765.776μg/g Cr or 0.785-1347.0μg/l), and Pb (6.606-83.937μg/g Cr or 9.459-80.826μg/l), except Pb was not associated with ALB. Infants in the highest Pb quartile (9.293-263.098μg/l) had the highest ß coefficients of urinary excretion of MDA, 8-OHdG, ALB, NAG, and Cr. Significant increasing trend in biomarkers across the quartiles of the three metals was seen in both mothers and infants (p_trend <0.001). A receiver operating characteristic analysis supported the predictive abilities of the four renal biomarkers in discriminating between low versus high metal quartiles. The interaction between heavy metals and oxidative stress contributed to the high excretions of renal biomarkers, but the mechanism remains unclear. These findings add to the limited evidence that low exposure to heavy metals in the general population is associated with alterations in renal function that could eventually progress to renal damage if exposure continues and that children are more susceptible due to the immaturity of their body organs.

Effects of empagliflozin on the urinary albumin-to-creatinine ratio in patients with type 2 diabetes and established cardiovascular disease: an exploratory analysis from the EMPA-REG OUTCOME randomised, placebo-controlled trial

BACKGROUND

In a pooled analysis of short-term trials, short-term treatment with the sodium-glucose co-transporter-2 (SGLT2) inhibitor empagliflozin reduced albuminuria in patients with type 2 diabetes and prevalent albuminuria. In this exploratory analysis of the EMPA-REG OUTCOME trial, we report the short-term and long-term effects of empagliflozin on albuminuria in patients with type 2 diabetes and established cardiovascular disease, according to patients' baseline albuminuria status.

METHODS

In this randomised, double-blind, placebo-controlled trial at 590 sites in 42 countries, we randomly assigned patients aged 18 years and older with type 2 diabetes and established cardiovascular disease (1:1:1) to empagliflozin 10 mg, empagliflozin 25 mg, or placebo in addition to standard of care until at least 691 patients experienced an adjudicated event included in the primary outcome. We did the randomisation with a computer-generated random-sequence and interactive voice-response and web-response system, stratified by HbA_1c, BMI, region, and estimated glomerular filtration rate. Patients, investigators, and individuals involved in analysis of trial data were masked to treatment assignment. The primary and secondary efficacy and safety endpoints of this trial have been reported previously. Here, we report urinary albumin-to-creatinine ratio (UACR) data for the pooled empagliflozin group versus placebo according to albuminuria status at baseline (normoalbuminuria: UACR <30 mg/g; microalbuminuria: UACR ≥30 to ≤300 mg/g; and macroalbuminuria: UACR >300 mg/g). We did the analysis with mixed-model repeated measures including prespecified and post-hoc tests. This study is completed and registered with ClinicalTrials.gov, number NCT01131676.

FINDINGS

Between Sept 1, 2010, and April 22, 2013, we randomly assigned 7028 patients to treatment groups and 7020 patients received treatment. At baseline, we had UACR data for 6953 patients: 4171 (59% of treated patients; 1382 assigned to placebo and 2789 assigned to empagliflozin) had normoalbuminuria, 2013 (29%; 675 assigned to placebo and 1338 assigned to empagliflozin) had microalbuminuria, and 769 (11%; 260 assigned to placebo and 509 assigned to empagliflozin) had macroalbuminuria. Median treatment duration was 2·6 years (IQR 2·0-3·4; 136 weeks) and median observation time was 3·1 years (2·2-3·6; 164 weeks). After short-term treatment at week 12, the placebo-adjusted geometric mean ratio of UACR change from baseline with empagliflozin was -7% (95% CI -12 to -2; p=0·013) in patients with normoalbuminuria, -25% (-31 to -19; p<0·0001) in patients with microalbuminuria, and -32% (-41 to -23; p<0·0001) in patients with macroalbuminuria. The reductions in UACR were maintained with empagliflozin in all three groups compared with placebo during long-term treatment when measured at 164 weeks. At follow-up, after cessation of treatment for a median of 34 or 35 days, UACR was lower in the empagliflozin versus placebo group in those with baseline microalbuminuria (placebo-corrected adjusted geometric mean ratio of relative change from baseline with empagliflozin: -22%, 95% CI -32 to -11; p=0·0003) or macroalbuminuria (-29%, -44 to -10; p=0·0048), but not for patients with baseline normoalbuminuria (1%, -8 to 10; p=0·8911). Patients treated with empagliflozin were more likely to experience a sustained improvement from microalbuminuria to normoalbuminuria (hazard ratio [HR] 1·43, 95% CI 1·22 to 1·67; p<0·0001) or from macroalbuminuria to microalbuminuria or normoalbuminuria (HR 1·82, 1·40 to 2·37; p<0·0001), and less likely to experience a sustained deterioration from normoalbuminuria to microalbuminuria or macroalbuminuria (HR 0·84, 0·74 to 0·95; p=0·0077). The proportions of patients with any adverse events, serious adverse events, and adverse events leading to discontinuation increased with worsening UACR status at baseline, but were similar between treatment groups. The proportion of patients with genital infections was greater with empagliflozin than placebo in all subgroups by UACR status.

INTERPRETATION

These results support short-term and long-term benefits of empagliflozin on urinary albumin excretion, irrespective of patients' albuminuria status at baseline.

FUNDING

Boehringer Ingelheim & Eli Lilly and Company Diabetes Alliance.

Predictive factors and prevalence of microalbuminuria in HIV-infected patients: a cross-sectional analysis

Background

Renal dysfunction is a common problem in the HIV+ population, due to the effect of both the HIV virus and the several classes of ARV drugs such as tenofovir (TDF). It is also known that the presence of renal damage correlates with cardiovascular risk and therefore with the risk of mortality of the patients accordingly. The detection of early renal damage is very important. Albuminuria and microalbuminuria are markers of early kidney disease and cardiovascular risk. The aim of the study is to evaluate the prevalence of microalbuminuria in a large polycentric sample, of unselected and consecutive HIV-patients followed as outpatients, and to assess its association with different therapeutic regimens.

Methods

We studied 326 patients with a mean age of 48.4 ± 1.6 years, treated at the Infectious Diseases Clinics of Chieti and Perugia for 48 weeks. The main metabolic parameters and the microalbuminuria levels in a single sample of urine were evaluated.

Results

Microalbuminuria was detected in 61.0% of patients at T0 and in 49.7% after 48 weeks of observation with a median values of 1.1 mg/L (IQR: 0-2.7) vs. 0 mg/L (IQR: 0-2.0). 70% of the enrolled population did not show changes in microalbuminuria levels over time, 19% showed improvement, and 11% of the population had a worsening of microalbuminuria levels without any alteration of creatinine, uric acid and GFR-MDRD. We also found a statistically significant association between the development of microalbuminuria and gender (p < 0.035), Arterial Hypertension (AH) (p < 0.028) and therapy with TDF (p < 0.050).

Conclusion

We showed a very high prevalence of microalbuminuria, much higher than the literature data; the use of TDF affects the renal function in a statistically significant way and should therefore be considered a risk factor for kidney damage, which can be early assessed with the measurement of microalbuminuria.

Sex difference in the risk for exercise-induced albuminuria correlates with hemoglobin A1C and abnormal exercise ECG test findings

BACKGROUND

Albuminuria is an established marker for endothelial dysfunction and cardiovascular risk in diabetes and prediabetes. Exercise induced albuminuria (EiA) appears earlier and may be a more sensitive biomarker for renal endothelial damage. We sought to examine the association between EiA, parameters of the metabolic syndrome, A1C levels, exercise ECG test results and sex related differences in a large cohort of healthy, pre-diabetic and diabetic subjects.

METHODS

A total of 3029 participants from the Tel-Aviv Medical Center Inflammation Survey cohort (mean age 46 years, 73% men) were analyzed. Multiple physiologic and metabolic parameters including A1C were collected and albuminuria was measured in all subjects before and immediately after completing an exercise ECG test.

RESULTS

Exercise increased urinary albumin to creatinine ratio (ΔEiA) by 2.8 (0-13.6) mg/g for median (IQR) compared to rest albuminuria (p < 0.001). An increase in ΔEiA was observed with accumulating parameters of the metabolic syndrome. ΔEiA showed significant interaction with sex and A1C levels; i.e. women with A1C > 6.5% had an increased risk of higher ΔEiA (p < 0.001). Using a cutoff of ΔEiA > 13 mg/g (top quartile) we found that women with ΔEiA > 13 mg/g were at greater risk for abnormal exercise ECG findings, (OR = 2.7, p = 0.001).

CONCLUSION

Exercise promotes excessive urinary albumin excretion in dysmetabolic patients. In women, a significant correlation exists between ΔEiA and A1C levels. A cutoff of ΔEiA > 13 mg/g in women may be used to identify populations at risk for abnormal exercise ECG test findings and perhaps increased cardiovascular risk. Future studies will be needed to further validate the usefulness of ΔEiA as a biomarker for cardiovascular risk in women with and without diabetes.

Assessment of the diagnostic value of different biomarkers in relation to various stages of diabetic nephropathy in type 2 diabetic patients

Albuminuria is widely used to indicate early phases of diabetic nephropathy although it is limited by the fact that structural damage might precede albumin excretion. This necessitates identifying better biomarkers that diagnose or predict diabetic nephropathy. This is a cross-sectional hospital based study recruiting type 2 diabetic patients cohort aged 35–75 years with diabetes duration of ≥10 years. Out of total eligible 467 patients, 200 patients were with normal albumin excretion, 184 patients with microalbuminuria and 83 patients with macroalbuminuria. All the patients were tested for the 22 selected biomarkers including serum, plasma and urinary markers. Sensitivity, specificity, and area under the curve (AUC) were calculated as measures of diagnostic accuracy. Out of the tested biomarkers, urinary transferrin, urinary Retinol binding protein (RBP) and serum osteopontin had the best diagnostic value for diabetic nephropathy presence based on the AUC value. The rest of the biomarkers had comparatively less or even no discriminative power. The urinary transferrin and RBP and serum osteopontin, had the best diagnostic value in type 2 diabetic patients at different stages of diabetic nephropathy. Further longitudinal prospective studies are needed to evaluate the predictive power of those markers for detecting diabetic nephropathy before any structural damage occurs.

Epidemiology of chronic kidney disease: think (at least) twice!

The introduction of the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines has substantially contributed to the early detection of different stages of chronic kidney disease (CKD). Several recent studies from different parts of the world mention a CKD prevalence of between 8 and 13%. There are several reasons the CKD prevalence found in a study of a particular population is clearly overestimated. The structure of the population pyramid (young or older age) of the study sample may result in high or low CKD prevalence. The absence of using an isotope dilution mass spectrometry creatinine assay can be the source of high bias in CKD prevalence. In addition, using an arbitrary single threshold of estimated glomerular filtration rate (eGFR; <60 mL/min/1.73 m2) for classifying CKD leads to a substantial 'overdiagnosis' (false positives) in the elderly (>65 years of age), particularly in those without albuminuria (or proteinuria), haematuria or hypertension. It also results in a significant 'underdiagnosis' (false negatives) in younger individuals with an eGFR >60 mL/min/1.73 m2 and below the third percentile for their age/gender category. The use of third percentile eGFR rates as a cut-off based on age/gender-specific reference values of eGFR allows the detection of these false positives and negatives. In the present article, we focus on an important and frequently omitted criterion in epidemiological studies: chronicity. Indeed, the two most important factors introducing a high number (up to 50%) of false positives are lack of confirming proteinuria and the absence of proof of chronicity of the eGFR found at first screening. There is an urgent need for quality studies of the prevalence of CKD using representative randomized samples of the population, applying the KDIGO guidelines correctly.

Choroidal thickness alterations in diabetic nephropathy patients with early or no diabetic retinopathy

PURPOSE

To assess changes in choroidal thickness (CT) in diabetes patients with and without diabetic nephropathy using enhanced depth imaging spectral domain optical coherence tomography (EDI-OCT).

METHODS

Thirty-five type 2 diabetes patients with a diagnosis of diabetic nephropathy (DNP) in nephrology department and 35 type 2 diabetes patients without nephropathy (non-DNP) were included in our prospective study consecutively. The control group comprised 34 healthy individuals. CT measurements were recorded under the fovea and at 1500 µm from the foveal center in the nasal and temporal sides. The study parameters also included age, refractive error, axial length, intraocular pressure, HbA1c, glomerular filtration rate and proteinuria amount.

RESULTS

The subfoveal, temporal and nasal choroidal thickness was noted to be thinner in patients with DNP compared with non-DNP and normal subjects (p < 0.05). However, CT measurements did not show any difference between the healthy and non-DNP group.

CONCLUSION

CT decreases significantly in diabetic patients when diabetic nephropathy accompanies diabetes mellitus.

The Association Between the Metabolic Syndrome and Metabolic Syndrome Score and Urine Microalbumin/Urine Creatinine Ratio and Glomerular Filtration Rate in Korean Adults With Obesity

OBJECTIVE

This study assessed the association between metabolic syndrome (MetS) and metabolic syndrome score (MSS) and the levels of urine microalbumin-urine creatinine ratio (uACR) and glomerular filtration rate (GFR) in Korean adults with obesity.

METHODS

Analyses of data obtained during the 2012 Korean National Health and Nutrition Examination Survey were restricted to that obtained from 1,612 adults aged ≥20 years with obesity.

RESULTS

After adjusting for relevant variables (excluding age), uACR levels were positively associated with MetS (P < .001) and MSS (P < .001), and GFR levels were inversely associated with MetS (P < .001) and MSS (P < .001). However, when further adjusting for age, uACR levels were positively associated with MetS (P < .001) and MSS (P < .001) levels, but GFR levels were not associated with MetS (P = .632) and MSS (P = .275) levels.

CONCLUSION

MetS and MSS were positively associated with uACR levels in Korean adults with obesity, but were not associated with GFR levels.