Estimated Glomerular Filtration Rate in Chronic Kidney Disease: A Critical Review of Estimate-Based Predictions of Individual Outcomes in Kidney Disease.

Chronic kidney disease (CKD) is generally regarded as a final common pathway of several renal diseases, often leading to end-stage kidney disease (ESKD) and a need for renal replacement therapy. Estimated GFR (eGFR) has been used to predict this outcome recognizing its robust association with renal disease progression and the eventual need for dialysis in large, mainly cross-sectional epidemiological studies. However, GFR is implicitly limited as follows: (1) GFR reflects only one of the many physiological functions of the kidney; (2) it is dependent on several non-renal factors; (3) it has intrinsic variability that is a function of dietary intake, fluid and cardiovascular status, and blood pressure especially with impaired autoregulation or medication use; (4) it has been shown to change with age with a unique non-linear pattern; and (5) eGFR may not correlate with GFR in certain conditions and disease states. Yet, many clinicians, especially our non-nephrologist colleagues, tend to regard eGFR obtained from a simple laboratory test as both a valid reflection of renal function and a reliable diagnostic tool in establishing the diagnosis of CKD. What is the validity of these beliefs? This review will critically reassess the limitations of such single-focused attention, with a particular focus on inter-individual variability. What does science actually tell us about the usefulness of eGFR in diagnosing CKD?

Disruption of the glomerular basement membrane associated with nutcracker syndrome and double inferior vena cava in Noonan syndrome: a case report.

BACKGROUND: Nutcracker syndrome (NCS) is characterized by compression of the left renal vein (LRV) between the aorta and the superior mesenteric artery. While rare, NCS was reported to be accompanied by double inferior vena cava (IVC). We herein report a case of Noonan syndrome (NS) with double IVC who presented with macrohematuria and proteinuria. CASE PRESENTATION: The patient was a 23-year-old man, who had been diagnosed with NS due to RIT1 mutation, after showing foamy macrohematuria 3 weeks previously. A physical examination revealed low-set ears and a webbed neck. A urinalysis showed hematuria and proteinuria, and urinary sediments showed more than 100 isomorphic red blood cells per high-power field. His proteinuria and albuminuria concentrations were 7.1 and 4.5 g/g⋅Cr, respectively. Three-dimensional contrast-enhanced computed tomography (CT) showed double IVC and narrowing of the LRV after interflow of the left IVC. The aortomesenteric angle on a sagittal reconstruction of the CT image was 14.7°. Cystoscopy revealed a flow of macrohematuria from the left ureteral opening. On Doppler ultrasonography, there was scant evidence to raise the suspicion of the nutcracker phenomenon. Since severe albuminuria continued, a left kidney biopsy was performed. Light microscopy showed red blood cells in Bowman's space and the tubular lumen. Electron microscopy revealed disruption of the glomerular basement membrane (GBM). Vulnerability of the GBM was suspected and a genetic analysis revealed a heterozygous mutation at c.4793 T > G (p.L1598R) in the COL4A3 gene. Screening for coagulation disorders revealed the factor VIII and von Willebrand factor (vWF) values were low, at 47.6 and 23%, respectively. A multimer analysis of vWF showed a normal multimer pattern and he was diagnosed with von Willebrand disease type 1. As the bleeding tendency was mild, replacement of factor VIII was not performed. His macrohematuria and proteinuria improved gradually without treatment, and his urinalysis results have been normal for more than 6 months. CONCLUSIONS: The present case showed macrohematuria and proteinuria due to NCS in NS with double IVC and von Willebrand disease type 1. The macrohematuria and proteinuria originated from glomerular hemorrhage because of vulnerability of the GBM due to COL4A3 mutation.

Latin American registry of renal involvement in COVID-19 disease. The relevance of assessing proteinuria throughout the clinical course.

The Latin American Society of Nephrology and Hypertension conducted a prospective cohort, multinational registry of Latin American patients with kidney impairment associated to COVID-19 infection with the objective to describe the characteristics of acute kidney disease under these circumstances. The study was carried out through open invitation in order to describe the characteristics of the disease in the region. Eight-hundred and seventy patients from 12 countries were included. Median age was 63 years (54-74), most of patients were male (68.4%) and with diverse comorbidities (87.2%). Acute kidney injury (AKI) was hospital-acquired in 64.7% and non-oliguric in 59.9%. Multiorgan dysfunction syndrome (MODS) due to COVID-19 and volume depletion were the main factors contributing to AKI (59.2% and 35.7% respectively). Kidney replacement therapy was started in 46.2%. Non-recovery of renal function was observed in 65.3%. 71.5% of patients were admitted to ICU and 72.2% underwent mechanical ventilation. Proteinuria at admission was present in 62.4% of patients and proteinuria during hospital-stay occurred in 37.5%. Those patients with proteinuria at admission had higher burden of comorbidities, higher baseline sCr, and MODS was severe. On the other hand, patients with de novo proteinuria had lower incidence of comorbidities and near normal sCr at admission, but showed adverse course of disease. COVID-19 MODS was the main cause of AKI in both groups. All-cause mortality of the general population was 57.4%, and it was associated to age, sepsis as cause of AKI, severity of condition at admission, oliguria, mechanical ventilation, non-recovery of renal function, in-hospital complications and hospital stay. In conclusion, our study contributes to a better knowledge of this condition and highlights the relevance of the detection of proteinuria throughout the clinical course.

Proteinuria during pregnancy: definition, pathophysiology, methodology, and clinical significance.

Qualitative and quantitative measurement of urine protein excretion is one of the most common tests performed during pregnancy. For more than 100 years, proteinuria was necessary for the diagnosis of preeclampsia, but recent guidelines recommend that proteinuria is sufficient but not necessary for the diagnosis. Still, in clinical practice, most patients with gestational hypertension will be diagnosed as having preeclampsia based on the presence of proteinuria. Although the reference standard for measuring urinary protein excretion is a 24-hour urine collection, spot urine protein-to-creatinine ratio is a reasonable "rule-out" test for proteinuria. Urine dipstick screening for proteinuria does not provide any clinical benefit and should not be used to diagnose proteinuria. The classic cutoff cited to define proteinuria during pregnancy is a value of >300 mg/24 hours or a urine protein-to-creatinine ratio of at least 0.3. Using this cutoff, the rate of isolated proteinuria in pregnancy may reach 8%, whereas preeclampsia occurs among 3% to 8% of pregnancies. Although this threshold is widely accepted, its origin is not based on evidence on adverse pregnancy outcomes but rather on expert opinion and results of small studies. After reviewing the available data, the most important factor that influences maternal and neonatal outcome is the severity of blood pressures and presence of end organ damage, rather than the excess protein excretion. Because the management of gestational hypertension and preeclampsia without severe features is almost identical in frequency of surveillance and timing of delivery, the separation into 2 disorders is unnecessary. If the management of women with gestational hypertension with a positive assessment of proteinuria will not change, we believe that urine assessment for proteinuria is unnecessary in women who develop new-onset blood pressure at or after 20 weeks' gestation. Furthermore, we do not recommend repeated measurement of proteinuria for women with preeclampsia, the amount of proteinuria does not seem to be related to poor maternal and neonatal outcomes, and monitoring proteinuria may lead to unindicated preterm deliveries and related neonatal complications. Our current diagnosis of preeclampsia in women with chronic kidney disease may be based on a change in protein excretion, a baseline protein excretion evaluation is critical in certain conditions such as chronic hypertension, diabetes, and autoimmune or other renal disorders. The current definition of superimposed preeclampsia possesses a diagnostic dilemma, and it is unclear whether a change in the baseline proteinuria reflects another systemic disease such as preeclampsia or whether women with chronic disease such as chronic hypertension or diabetes will experience a different "normal" pattern of protein excretion during pregnancy. Finally, limited data are available regarding angiogenic and other biomarkers in women with chronic kidney disease as a potential aid in distinguishing the worsening of baseline chronic kidney disease and chronic hypertension from superimposed preeclampsia.

Decline in renal function associated with cardiovascular autonomic neuropathy positively coordinated with proteinuria in patients with type 2 diabetes.

AIMS/INTRODUCTION: To investigate the association between cardiovascular autonomic neuropathy (CAN) assessed by the coefficient of variation of the R-R interval and the reduction in the estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes. MATERIALS AND METHODS: This retrospective observational cohort study enrolled type 2 diabetes patients who had their coefficient of variation of the R-R interval measured on an electrocardiogram from January 2005 to December 2018. CAN was defined using the reference coefficient of variation of the R-R interval value based on age and sex. The primary outcome was set as a 40% eGFR decline from baseline. Regression analyses using the Cox proportional hazards model were carried out to evaluate the association. RESULTS: Of the 831 patients, 118 (14.2%) were diagnosed with CAN. In the analysis of the primary outcome, the median follow-up period was 5.3 years, and 25 (21.2%) patients with CAN and 78 (10.9%) patients without CAN developed a 40% eGFR decline. In the univariate regression analysis, CAN was significantly associated with a 40% eGFR decline (hazard ratio 2.42, 95% confidence interval 1.54-3.80). In the multivariate analysis, CAN remained almost significant after adjusting for the prognostic risk factors for CAN and the decline in the renal function, and an interaction with proteinuria was found. In analyses for the interaction effect between CAN and proteinuria, the presence of CAN synergistically increased the risk of an eGFR decline in patients with macroproteinuria. CONCLUSIONS: CAN strongly increased the risk of a 40% eGFR decline from baseline, especially in type 2 diabetes patients with macroproteinuria.

Oxidized LDL Is Associated with eGFR Decline in Proteinuric Diabetic Kidney Disease: A Cohort Study.

Diabetic kidney disease (DKD) is a highly heterogenous disease, including the proteinuric and the nonproteinuric pattern. Oxidized low-density lipoprotein (ox-LDL) is progressively increased in DKD and causes direct damage to kidney tubular epithelial cells through a mechanism similar to that underlying the deleterious effect of lipid peroxides in the vascular endothelium. We aimed to examine the association between plasma ox-LDL cholesterol and clinical endpoints in DKD patients. Ninety-one patients with established proteinuric DKD and diabetic retinopathy were enrolled and prospectively followed for 10 years or the occurrence of death, or at least 30% decline in eGFR, or progression to end-stage kidney disease (ESKD) requiring renal replacement therapy (primary outcome). At the end of the study, both eGFR and proteinuria were reassessed. Secondary outcomes of the study were the percentage change in eGFR and proteinuria over time for each patient. At baseline, patients were divided into 2 groups according to the median ox-LDL value (i.e., below or equal and above 66.22 U/L). Both Kaplan-Meier curves (p = 0.001, log-rank test) and univariate Cox regression analysis showed that high ox-LDL was associated with the primary outcome (HR = 3.42, 95%CI = 1.55 - 7.56, p = 0.002). After adjustment for various well-known cofounders, multivariate Cox analysis showed that the association between increased circulating ox-LDL levels and the composite kidney endpoint remained significant (HR = 2.87, 95%CI = 1.14-7.20, p = 0.025). Regarding the secondary outcome of eGFR decline, the assessment of areas under the curves (AUC) showed that ox-LDL outperformed several cofounding factors (AUC 71%, 95%CI = 0.59 - 0.83, p = 0.001) and had better accuracy to predict deterioration of eGFR over time than baseline proteinuria (AUC 67%, 95%CI = 0.54 - 0.79, p = 0.014). Increased ox-LDL might be associated with disease progression in proteinuric DKD.

Sodium-Glucose Cotransporter-2 Inhibitors in Patients with Hereditary Podocytopathies, Alport Syndrome, and FSGS: A Case Series to Better Plan a Large-Scale Study.

Hereditary diseases of the glomerular filtration barrier are characterized by a more vulnerable glomerular basement membrane and dysfunctional podocytes. Recent clinical trials have demonstrated the nephroprotective effect of sodium-glucose cotransporter-2 inhibitors (SGLT2i) in chronic kidney disease (CKD). SGLT2-mediated afferent arteriole vasoconstriction is hypothesized to correct the hemodynamic overload of the glomerular filtration barrier in hereditary podocytopathies. To test this hypothesis, we report data in a case series of patients with Alport syndrome and focal segmental glomerulosclerosis (FSGS) with respect of the early effect of SGLT2i on the kidney function. Mean duration of treatment was 4.5 (±2.9) months. Mean serum creatinine before and after SGLT-2i initiation was 1.46 (±0.42) and 1.58 (±0.55) mg/dL, respectively, with a median estimated glomerular filtration rate of 64 (±27) before and 64 (±32) mL/min/1.73 m2 after initiation of SGLT2i. Mean urinary albumin-creatinine ratio in mg/g creatinine before SGLT-2i initiation was 1827 (±1560) and decreased by almost 40% to 1127 (±854) after SGLT2i initiation. To our knowledge, this is the first case series on the effect and safety of SGLT2i in patients with hereditary podocytopathies. Specific large-scale trials in podocytopathies are needed to confirm our findings in this population with a tremendous unmet medical need for more effective, early on, and safe nephroprotective therapies.

Adipose-derived mesenchymal stem cells protects renal function in a rat model of emphysema.

BACKGROUND AND OBJECTIVE: The link between lung disease and kidney disorders has already been confirmed. Previous studies have documented that obstructive pulmonary disease is an independent predictor of decreased renal function, which reduces glomerular filtration rate. Recently, mesenchymal stem cells are the most important cell used in cell therapy. Accordingly, the present experiment was designed to evaluate the efficacy of adipose-derived mesenchymal stem cells (AMSCs) on improvement of renal function in elastase induced-pulmonary emphysema rats. MATERIALS AND METHODS: Thirty male Sprague-Dawley rats divided into the 3 groups. Following intra-tracheal administration of elastase, the in vivo emphysema model established and confirmed according to the specific markers. Subsequently, systemic AMSCs injection was developed. the kidney injuries markers such as Blood urea nitrogen (BUN), creatinine, sodium and potassium as well as the kidney histopathologic parameters were assessed in all groups. Moreover, the oxidative stress markers levels including Malondialdehyde (MDA), Total antioxidant capacity (TAC), Catalase (CAT) and Glutathione peroxidase (GPx) were measured in kidney tissue and also inflammatory cytokines including IL-10, IL-6, and IFN-Ƴ were assessed in serum samples. RESULTS: The marked rise in kidney injuries markers were observed which showed by enhancement of BUN and Creatinine levels in emphysema rats compared to the control. Furthermore, the results demonstrated increases in MDA levels and decreases in antioxidant activity which was in line with increases in inflammation cytokines in renal tissue. Conversely, AMSCs treatment improved renal function as shown by the decreases BUN, Creatinine and proteinuria. Furthermore, renal histological assay demonstrate improvement in glomerular and tubular damage and inflammatory cells accumulation. CONCLUSIONS: Our results documented the promising kidney-protective properties of Adipose-Derived Mesenchymal Stem Cells in the kidney injuries induced by emphysema.

Evaluation of Salivary Indoxyl Sulfate with Proteinuria for Predicting Graft Deterioration in Kidney Transplant Recipients.

Acute kidney injury (AKI) is a significant risk factor for developing chronic kidney disease and progression to end-stage renal disease in elderly patients. AKI is also a relatively common complication after kidney transplantation (KTx) associated with graft failure. Since the lifespan of a transplanted kidney is limited, the risk of the loss/deterioration of graft function (DoGF) should be estimated to apply the preventive treatment. The collection of saliva and urine is more convenient than collecting blood and can be performed at home. The study aimed to verify whether non-invasive biomarkers, determined in saliva and urine, may be useful in the prediction of DoGF in kidney transplant recipients (KTRs) (n = 92). Salivary and serum toxins (p-cresol sulfate, pCS; indoxyl sulfate, IS) concentrations were determined using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Urinary proteins, hemoglobin, and glucose were measured using a semi-quantitative strip test. Salivary IS (odds ratio (OR) = 1.19), and proteinuria (OR = 3.69) were demonstrated as independent factors for the prediction of DoGF. Satisfactory discriminatory power (area under the receiver operating characteristic curve (AUC) = 0.71 ± 0.07) and calibration of the model were obtained. The model showed that categories of the increasing probability of the risk of DoGF are associated with the decreased risk of graft survival. The non-invasive diagnostic biomarkers are a useful screening tool to identify high-risk patients for DoGF.

Uricase deficiency causes mild and multiple organ injuries in rats.

Uricase-deficient rats could be one of the optimal model animals to study hyperuricemia. The present study aimed to find the biological differences between uricase-deficient (Kunming-DY rats) and wild-type male rats. Uricase-deficient rats and wild-type rats were commonly bred. Their body weight, water and food consumption, 24-h urine and feces, uric acid in serum and organs, and serum indexes were recorded or assayed. Organs, including the heart, liver, spleen, lung, kidney, thymus, stomach, duodenum, and ileum, were examined using a routine hematoxylin-eosin staining assay. We found that the growth of male uricase-deficient rats was retarded. These rats excreted more urine than the wild-type rats. Their organ indexes (organ weight body weight ratio), of the heart, liver, kidney, and thymus significantly increased, while those of the stomach and small intestine significantly decreased. The uricase-deficient rats had a significantly higher level of serum uric acid and excreted more uric acid via urine at a higher concentration. Except for the liver, uric acid increased in organs and intestinal juice of uricase-deficient rats. Histological examination of the uricase-deficient rats showed mild injuries to the heart, liver, spleen, lung, kidney, thymus, stomach, duodenum, and ileum. Our results suggest that uricase-deficient rats have a different biological pattern from the wild-type rats. Uricase deficiency causes growth retardation of young male rats and the subsequent increase in serum uric acid results in mild organs injuries, especially in the kidney and liver.

Renal Histologic Analysis Provides Complementary Information to Kidney Function Measurement for Patients with Early Diabetic or Hypertensive Disease.

BACKGROUND: Patients with diabetic or hypertensive kidney disease rarely undergo kidney biopsy because nephrologists commonly believe that biopsy-related risk outweighs the potential benefits of obtaining histologic information to guide clinical decisions. Although kidney function is acutely regulated, histologic changes such as interstitial fibrosis, tubular atrophy, and glomerulosclerosis may represent chronic kidney damage, and thus might provide additional information about disease severity. However, whether histologic analysis provides information complementary to clinically used kidney function measurements, such as eGFR and proteinuria, is unclear. METHODS: We performed a standardized semiquantitative histologic analysis of 859 nephrectomies obtained from individuals with or without diabetes mellitus or hypertension and varying degrees of kidney dysfunction. Changes in glomeruli, tubules, interstitium, and the vasculature were scored using 17 descriptive parameters in a standardized manner. We used multivariable linear and logistic regression analyses and unbiased, hierarchical clustering to assess associations between histologic alterations and clinical variables. RESULTS: At CKD stages 3-5, eGFR correlates reasonably well with the degree of glomerulosclerosis and interstitial fibrosis and tubular atrophy (IFTA). In patients with CKD stages 1-2, the degree of histologic damage was highly variable and eGFR poorly estimated the degree of damage. Individuals with diabetes mellitus, hypertension, or Black race had significantly more glomerulosclerosis and IFTA, at the same eGFR level. Inclusion of glomerulosclerosis improved the kidney function decline estimation, even at early disease stages. CONCLUSIONS: Histologic analysis is an important complementary method for kidney disease evaluation, especially at early disease stages. Some individuals present with relatively severe structural damage despite preserved eGFR.

The association between frailty and chronic kidney disease; cross-sectional analysis of the Nambu Cohort Study.

BACKGROUND: Both frailty and chronic kidney disease (CKD) increase with age and share many similarities. Many studies have demonstrated an association between frailty and chronic kidney disease (CKD), but an association with dipstick proteinuria is limited. METHODS: This is the cross-sectional analysis of the Nambu Cohort Study at the beginning of observation. Frailty was diagnosed using Kihon Checklist. Logistic analysis was used to evaluate the association between frailty and CKD or dipstick proteinuria. RESULTS: Among a total of 630 outpatients [age, 78 (70-84) years, men, 50%], the prevalence of patients with pre-frailty and frailty was 32% and 40%, respectively. The proportion of patients with pre-frailty and frailty increased with decreasing estimated glomerular filtration rate (eGFR) and increasing dipstick proteinuria levels. The odds ratios (95% confidence intervals) for CKD stage of 60 < eGFR ≤ 45 ml/min/1.73 m2, and 45 ml/min/1.73 m2 < eGFR for frailty was 0.87 (0.56-1.35) and 2.54 (1.46-4.53), respectively, compared with non-CKD as a reference. Furthermore, the odds ratios for the frailty of dipstick proteinuria with ± and + or over were 1.36 (0.88-2.09) and 1.78 (1.00-3.17), respectively, when dipstick proteinuria-was used as a reference. Moreover, the combination of eGFR and dipstick proteinuria levels increased the odds ratio for pre-frailty and frailty. CONCLUSION: Elderly patients with CKD had a higher prevalence of pre-frailty and frailty. By adding urinary protein information to eGFR, the link between CKD and frailty becomes even more robust.

Iron deficiency in proteinuric children with nephrotic syndrome: A cross-sectional pilot study.

Massive proteinuria in nephrotic syndrome causes depletion of various proteins. Iron deficiency can occur due to urinary loss of iron, transferrin, and soluble transferrin receptors. We conducted this cross-sectional study of 52 children with proteinuric nephrotic syndrome, aged 1-12 years (mean 7.1±2.7 years). Hemoglobin (Hb), RBC indices (MCV, MCH, MCHC), percentage of hypochromic RBCs (Hypo-He), reticulocyte hemoglobin content (Ret-He), and serum ferritin were examined. Seven (13%) patients had iron deficiency anemia and another 10 (19%) exhibited iron deficiency. A higher proportion of children with steroid-resistant disease had anemia than did steroid-sensitive children (P=0.076). Thus, children with nephrotic syndrome may have iron deficiency (32.7%), which needs to be screened.

Pathophysiology of COVID-19-associated acute kidney injury.

Although respiratory failure and hypoxaemia are the main manifestations of COVID-19, kidney involvement is also common. Available evidence supports a number of potential pathophysiological pathways through which acute kidney injury (AKI) can develop in the context of SARS-CoV-2 infection. Histopathological findings have highlighted both similarities and differences between AKI in patients with COVID-19 and in those with AKI in non-COVID-related sepsis. Acute tubular injury is common, although it is often mild, despite markedly reduced kidney function. Systemic haemodynamic instability very likely contributes to tubular injury. Despite descriptions of COVID-19 as a cytokine storm syndrome, levels of circulating cytokines are often lower in patients with COVID-19 than in patients with acute respiratory distress syndrome with causes other than COVID-19. Tissue inflammation and local immune cell infiltration have been repeatedly observed and might have a critical role in kidney injury, as might endothelial injury and microvascular thrombi. Findings of high viral load in patients who have died with AKI suggest a contribution of viral invasion in the kidneys, although the issue of renal tropism remains controversial. An impaired type I interferon response has also been reported in patients with severe COVID-19. In light of these observations, the potential pathophysiological mechanisms of COVID-19-associated AKI may provide insights into therapeutic strategies.

Earlier onset of proteinuria or hypertension is a predictor of progression from gestational hypertension or gestational proteinuria to preeclampsia.

Although gestational hypertension (GH) is a well-known disorder, gestational proteinuria (GP) has been far less emphasized. According to international criteria, hypertensive disorders of pregnancy include GH but not GP. Previous studies have not revealed the predictors of progression from GP to preeclampsia or those of progression from GH to preeclampsia. We aimed to determine both sets of predictors. A retrospective cohort study was conducted with singleton pregnant women who delivered at 22 gestational weeks or later. Preeclampsia was divided into three types: new onset of hypertension/proteinuria at 20 gestational weeks or later and additional new onset of other symptoms at < 7 days or at ≥ 7 days later. Of 94 women with preeclampsia, 20 exhibited proteinuria before preeclampsia, 14 experienced hypertension before preeclampsia, and 60 exhibited simultaneous new onset of both hypertension and proteinuria before preeclampsia; the outcomes of all types were similar. Of 34 women with presumptive GP, 58.8% developed preeclampsia; this proportion was significantly higher than that of 89 women with presumptive GH who developed preeclampsia (15.7%). According to multivariate logistic regression models, earlier onset of hypertension/proteinuria (before or at 34.7/33.9 gestational weeks) was a predicator for progression from presumptive GH/GP to preeclampsia (odds ratios: 1.21/1.21, P value: 0.0044/0.0477, respectively).

Preoperative proteinuria may be a risk factor for postoperative acute kidney injury：a meta-analysis.

OBJECTIVE: To investigate the relationship between preoperative proteinuria and postoperative acute kidney injury (AKI). METHODS: We performed a search on databases included PubMed, Embase, the Cochrane Library, and Web of Science, from December 2009 to September 2020. Data extracted from eligible studies were synthesized to calculate the odds ratio (OR) and 95% confidence interval (CI). A fixed or random effects model was applied to calculate the pooled OR based on heterogeneity through the included studies. RESULTS: This meta-analysis of 11 observational studies included 203,987 participants, of whom 21,621 patients suffered from postoperative AKI and 182,366 patients did not suffer from postoperative AKI. The combined results demonstrated that preoperative proteinuria is an independent risk factor for postoperative AKI (adjusted OR = 1.65, 95%CI:1.44-1.89, p < 0.001). Subgroup analysis showed that both preoperative mild proteinuria (adjusted OR = 1.30, 95%CI:1.24-1.36, p < 0.001) and preoperative heavy proteinuria (adjusted OR = 1.93, 95%CI:1.65-2.27, p < 0.001) were independent risk factors for postoperative AKI. The heterogeneity was combined because its values were lower. Further subgroup analysis found that preoperative proteinuria measured using dipstick was an independent risk factor for postoperative AKI (adjusted OR = 1.48, 95%CI:1.37-1.60, p < 0.001). Finally, preoperative proteinuria was an independent risk factor for postoperative AKI in the non-cardiac surgery group (adjusted OR = 2.06, 95%CI:1.31-3.24, p = 0.002) and cardiac surgery group (adjusted OR = 1.69, 95%CI:1.39-2.06, p < 0.001). CONCLUSION: Preoperative proteinuria is an independent risk factor for postoperative AKI and in instances when proteinuria is detected using dipsticks.

From Proteinuria to Fibrosis: An Update on Pathophysiology and Treatment Options.

BACKGROUND: Proteinuria is a key biomarker in nephrology. It is central to diagnosis and risk assessment and the primary target of many important therapies. Etiologies resulting in pathological proteinuria include congenital and acquired disorders, as well as both glomerular (immune/non-immune mediated) and tubular defects. SUMMARY: Untreated proteinuria is strongly linked to progressive loss of kidney function and kidney failure. Excess protein reaching the renal tubules is ordinarily resorbed by the tubular epithelium. However, when these mechanisms are overwhelmed, a variety of inflammatory and fibrotic pathways are activated, causing both interstitial fibrosis and glomerulosclerosis. Nevertheless, the specific mechanisms underlying this are complex and remain incompletely understood. Recently, a number of treatments, in addition to angiotensin system blockade, have been shown to effectively slow the progression of proteinuric chronic kidney disease. However, additional therapies are clearly needed. Key message: This review provides an update on the pathophysiology of proteinuria, the pathways leading to fibrosis, and an overview of current and emerging therapies.

Organ-Specific Monitoring of Solitary Kidney after Living Donation by Using Markers of Glomerular Filtration Rate and Urinary Proteins.

BACKGROUND: Effective follow-up after living kidney donation is important for maintaining the renal function of the donor. We investigated whether the estimated glomerular filtration rate (eGFR) and urinary protein and enzyme levels can provide important information regarding the state of the remaining kidney after donor nephrectomy. METHODS: Seventy-five living donations were included (prospective/retrospective) in the study. The following parameters were measured up to 1 year after donor nephrectomy: serum creatinine and cystatin C as markers of the GFR; the high-molecular-weight urinary proteins as markers of glomerular injury; and the low-molecular-weight urinary proteins and urinary enzymes as markers of tubular function. RESULTS: One year after kidney donation, the creatinine and cystatin C values were 1.38-fold increased than their initial values, while the eGFR was 32% lower. At that time, 38% of donors had a moderate or high risk of CKD progression. The biochemical urinary glomerular and tubular kidney markers examined showed different behaviors. After a transient increase, the glomerular proteins normalized. Conversely, the detection of low-molecular-weight urinary proteins and enzymes reflected mild tubular damage at the end of the study period. CONCLUSIONS: Our findings suggest that for the evaluation of mild tubular damage, low-molecular-weight marker proteins should be included in the urine diagnostic of a personalized living kidney donor follow-up.

Associations Between Kidney Function, Proteinuria, and the Risk of Kidney Cancer: A Nationwide Cohort Study Involving 10 Million Participants.

Chronic kidney disease in its later stages is associated with increased risk of kidney cancer. We investigated whether chronic kidney disease at milder stages is associated with increased kidney cancer risk, using a retrospectively selected cohort of 9,809,317 adults in the Republic of Korea who participated in a nationwide health screening (2009-2016). We examined the impact of estimated glomerular filtration rate (eGFR), dipstick proteinuria, and interactive associations between the 2 factors on the risk of incident kidney cancer. During a median follow-up period of 7.3 years, 10,634 kidney cancers were identified. After adjustment for multiple confounders, participants with a reduced eGFR had an increased risk of kidney cancer (for eGFR <30 mL/minute/1.73 m2, adjusted hazard ratio = 1.18 (95% confidence interval: 1.01, 1.39); for eGFR 30-59 mL/minute/1.73 m2, adjusted hazard ratio = 1.22 (95% confidence interval: 1.14, 1.31)) compared with those with an eGFR of 60-89 mL/minute/1.73 m2. A dose-response relationship between the severity of proteinuria and incident kidney cancer was observed. Analyses of joint effects of eGFR and dipstick proteinuria showed that with the presence of proteinuria, kidney cancer incidence was markedly increased along with decreasing eGFR. Reduced eGFR and proteinuria are significantly associated with subsequent risk of kidney cancer, possibly in a synergistic manner.

Progression from isolated gestational proteinuria to preeclampsia with severe features.

INTRODUCTION: The association between the degree of isolated gestational proteinuria and preeclampsia with severe features and other placental-mediated complications is controversial. The aim of this study was to evaluate whether a higher isolated proteinuria level is associated with an increased frequency of preeclampsia with severe features. MATERIAL AND METHODS: This retrospective cohort study included pregnant women who were past 24 weeks of gestation and were diagnosed as having new-onset proteinuria ≥300 mg in a 24-h urine collection. Exclusion criteria included diagnosis of preeclampsia within 72 h from admission, chronic renal disease or chronic hypertension. The study population was divided into tertiles by proteinuria level and the association with preeclampsia with severe features was assessed in both bivariable and multivariable analysis. The main outcome measures was the development of preeclampsia with severe features. RESULTS: Overall, 165 women were diagnosed with isolated gestational proteinuria, and 38 (23.0%) of them developed preeclampsia with severe features. Women in the increasing proteinuria tertile were more likely to develop preeclampsia with severe features (5.5%, 21.8%, 41.8%, respectively; p = 0.004). A multivariable logistic regression model controlling for background characteristics as well as gestational age at diagnosis, blood pressure, and kidney and liver function tests showed an increased risk of 14% to develop preeclampsia with severe features for every 500-mg rise in proteinuria level (adjusted odds ratio = 1.14, 95% confidence interval 1.03-1.27). CONCLUSIONS: A higher isolated gestational proteinuria level was associated with an increased risk to develop preeclampsia with severe features among pregnant women past 24 weeks of gestation.