Background. The utility of renal biopsy in patients with diabetes is highly debated. Diabetics with rapidly worsening renal disease are often ‘clinically’ labelled as having diabetic nephropathy (DN), whereas, in many cases, they are rather developing a non-diabetic renal disease (NDRD) or mixed forms (DN + NDRD). Methods. We performed a systematic search for studies on patients with diabetes with data on the frequency of DN, NDRD and mixed forms, and assessed the positive predictive values (PPVs) and odds ratios (ORs) for such diagnoses by meta-analysing single-study prevalence. Possible factors explaining heterogeneity among the different diagnoses were explored by meta-regression. Results. In the 48 included studies (n = 4876), the prevalence of DN, NDRD and mixed forms ranged from 6.5 to 94%, 3 to 82.9% and 4 to 45.5% of the overall diagnoses, respectively. IgA nephropathy was the most common NDRD (3–59%). PPVs for DN, NDRD and mixed forms were 50.1% [95% confidence interval (CI): 44.7–55.2], 36.9% (95% CI: 32.3–41.8) and 19.7% (95% CI: 16.3–23.6), respectively. The PPV when combining NDRD and mixed forms was 49.2% (95% CI: 43.8–54.5). Meta-regression identified systolic pressure, HbA1c, diabetes duration and retinopathy as factors explaining heterogeneity for NDRD, creatinine and glomerular filtration rate for mixed forms and only serum creatinine for DN. ORs of DN versus NDRD and mixed forms were 1.71 (95% CI: 1.54–1.91) and 4.1 (95% CI: 3.43–4.80), respectively. Conclusions. NDRD are highly prevalent in patients with diabetes. Clinical judgment alone can lead to wrong diagnoses and delay the establishment of adequate therapies. Risk stratification according to individual factors is needed for selecting patients who might benefit from biopsy.

Background: Although the number of patients reaching end-stage kidney disease without a biopsy-proven diagnosis is increasing, the utility of renal biopsy is still an object of debate. We analyzed epidemiological data and the main indications for renal biopsy with a systematic, evidence-based review at current literature. Summary: There is a high discrepancy observed in biopsy rates and in the epidemiology of glomerular diseases worldwide, related to the different time frame of the analyzed reports, lack of data collection, the different reference source population and the heterogeneity of indications. The evidence-based analysis of indications showed that renal biopsy should be crucial in adults with nephrotic syndrome or urinary abnormalities as coexistent hematuria and proteinuria and in corticosteroid resistant-children with severe proteinuria. The knowledge of renal histology can change the clinical management in patients with acute kidney injury significantly, after the exclusion of pre-renal or obstructive causes of kidney damage. Scarce evidence indicates that renal biopsy can be useful in patients with advanced chronic kidney disease and its use should always be considered after weighing the benefits and potential risks. Renal biopsy should be crucial in patients with renal involvement due to systemic disease. In patients with diabetes with atypical features, renal biopsy may be fundamental to diagnose an unexpected parenchymal disease mislabeled as diabetic nephropathy. Finally, in elderly patients, the indications and the risks are not different from those in the general population. Key Message: Renal biopsy still remains a concrete approach for managing a substantial percentage of renal diseases.

Background: Acute kidney injury (AKI), even if followed by renal recovery, is a risk factor for the future development of chronic kidney disease (CKD) and end-sta

Urinary tract infection (UTI) represents the most common infection after kidney transplantation; it is associated with an increased risk for acute kidney rejection and impaired graft function in the early post-transplant period. Kidney transplant recipients with UTIs are often clinically asymptomatic due to the immunosuppressive therapy; however, asymptomatic bacteriuria may progress to acute pyelonephritis, bacteremia and urosepsis, particularly in the early post-transplant period, that are independent risk factors for short and long-term graft and patient survival. This article reviews the definitions, incidence, risk factors and the management of UTI in kidney transplant recipients; furthermore, the main controversial and still unanswered questions, regarding the causes of recurrent UTIs, adequate use of antibiotics to avoid antibiotic resistance, dosing and timing for prophylaxis and treatment of symptomatic infections, are also discussed. The emerging definition of urinary microbiota introduces new concepts in understanding the complexity of the disease and might represent the future target for therapeutic interventions.

Klotho is an anti‐aging factor mainly produced by renal tubular epithelial cells (TEC) with pleiotropic functions. Klotho is down‐regulated in acute kidney injury in native kidney; however, the modulation of Klotho in kidney transplantation has not been investigated. In a swine model of ischemia/reperfusion injury (IRI), we observed a remarkable reduction of renal Klotho by 24 h from IRI. Complement inhibition by C1‐inhibitor preserved Klotho expression in vivo by abrogating nuclear factor kappa B (NF‐kB) signaling. In accordance, complement anaphylotoxin C5a led to a significant down‐regulation of Klotho in TEC in vitro that was NF‐kB mediated. Analysis of Klotho in kidneys from cadaveric donors demonstrated a significant expression of Klotho in pre‐implantation biopsies; however, patients affected by delayed graft function (DGF) showed a profound down‐regulation of Klotho compared with patients with early graft function. Quantification of serum Klotho after 2 years from transplantation demonstrated significant lower levels in DGF patients. Our data demonstrated that complement might be pivotal in the down‐regulation of Klotho in IRI leading to a permanent deficiency after years from transplantation. Considering the anti‐senescence and anti‐fibrotic effects of Klotho at renal levels, we hypothesize that this acquired deficiency of Klotho might contribute to DGF‐associated chronic allograft dysfunction.

Several studies have shown that long-term survival after acute kidney injury (AKI) is reduced even if there is clinical recovery. However, we recently reported that in septic shock patients those that recover from AKI have survival similar to patients without AKI. Here, we studied a cohort with less severe sepsis to examine the effects of AKI on longer-term survival as a function of recovery by discharge. We analyzed patients with community-acquired pneumonia from the Genetic and Inflammatory Markers of Sepsis (GenIMS) cohort. We included patients who developed AKI (KDIGO stages 2–3) and defined renal recovery as alive at hospital discharge with return of SCr to within 150% of baseline without dialysis. Our primary outcome was survival up to 3 years analyzed using Gray’s model. Of the 1742 patients who survived to hospital discharge, stage 2–3 AKI occurred in 262 (15%), of which 111 (42.4%) recovered. Compared to recovered patients, patients without recovery were older (75 ±14 vs 69 ±15 years, p<0.001) and were more likely to have at least stage 1 AKI on day 1 (83% vs 52%, p<0.001). Overall, 445 patients (25.5%) died during follow-up, 23.4% (347/1480) for no AKI, 28% (31/111) for AKI with recovery and 44.3% (67/151) for AKI without recovery. Patients who did not recover had worse survival compared to no AKI (HR range 1.05–2.46, p = 0.01), while recovering patients had similar survival compared to no AKI (HR 1.01, 95%CI 0.69–1.47, p = 0.96). Absence of AKI on day 1, no in-hospital renal replacement therapy (RRT), higher Apache III score and higher baseline SCr were associated with recovery after AKI. In patients with sepsis, recovery by hospital discharge is associated with long-term survival similar to patients without AKI.