Background . IgG4‐related disease is a new disease entity, but little attention was drawn to urinary system involvement besides nephritis or nephropathy. Here, we described clinical, radiological, and pathological manifestations of IgG4‐related urinary disease (IgG4‐RUD) and assess its treatment responses. Methods . We conducted a retrospective study enrolling 65 IgG4‐RUD patients from an IgG4‐related disease (IgG4‐RD) cohort of the Peking Union Medical College Hospital. Clinical, laboratory, radiological, pathological data were collected, and treatment response to immunosuppressants were analysed. Results . IgG4‐related interstitial nephritis (TIN, 32.3%), glomerular nephritis (GN, 7.7%), renal pelvis and ureter involvement (21.5%), abnormal radiology with quiescent clinical presentation (13.8%), and renal parenchymal lesion plus retroperitoneal fibrosis (RPF, 18.5%) were major lesion types of IgG4‐RUD. All patients had elevated serum IgG4, 76.9% had hyperglobulinemia, and 92.3% had elevated serum IgE at diagnosis. IgG4‐TIN patients presented with renal dysfunction, and 94.3% had low serum complement C3 and IgG4‐GN presented with nephrotic syndrome, while renal pelvis and ureter involvement had normal renal function and urinalysis. IgG4‐RPF with renal parenchymal involvement presented with acute renal dysfunction and required emergency medical intervention. Renal cortex low‐density areas, parenchyma or pelvis nodular mass, bilateral enlargement of the kidney, and renal pelvis and ureter mass/wall thickening were specific image patterns of IgG4‐RUD. Infiltration of plasma lymphocytes and storiform fibrosis were histopathological features of IgG4‐RUD. Patients showed satisfactory responses to immunosuppressive treatment, but complete recovery of renal function was difficult to achieve in IgG4‐TIN. Four patients (6.2%) experienced clinical relapses during the maintenance period. Conclusion . IgG4‐RUD had diverse lesion types and distinctive manifestations. Radiological examinations were helpful for diagnosis and treatment evaluation. Patients showed good initial response to immunosuppressive treatment but relapses could occur at the maintenance period.

Renal involvement has been implicated in coronavirus disease 2019 (COVID-19), but the related prevalence and prognosis were largely unknown. In this meta-analysis, we searched the literature from PubMed, Embase, through bioRxiv, and medRxiv until April 26, 2020. Studies reporting chronic kidney diseases (CKDs) and/or acute kidney injury (AKI) were included. Demographics, relevant data of disease severity, and patient's prognosis were extracted and aggregated. Twenty-one thousand one hundred sixty-four patients from 52 peer-reviewed studies were included. Thirty-seven studies (n = 16,922) reported CKD in COVID-19 patients at diagnosis, and the pooled prevalence was 3.52% (95% CI, 1.98–5.48%; I² = 93%). Subgroup analysis showed that CKD prevalence was higher in severe cases [odds ratio (OR), 3.42; 95% CI 2.05–5.61; I² = 0%] compared to those with non-severe disease and deceased cases (6.46, 3.40–12.29; I² = 1%) compared with survivors. Pooled prevalence of CKD was lower in Chinese patients (2.56%; 95% CI, 1.79–3.47%; I² = 80%) compared to those outside of China (6.32%; 95% CI, 0.9–16.12%; I² = 93%) (p = 0.08). The summary estimates for AKI prevalence was 11.46% (95% CI, 6.93–16.94%). Patients with AKI had a higher prevalence of developing into severe cases (OR, 6.97; 95% CI, 3.53–13.75; I² = 0%) and mortality risk (45.79, 36.88–56.85; I² = 17%). The prevalence estimates of CKD or AKI were not significantly different from preprint publications (p > 0.05). Our study indicates that renal condition, either in CKD or AKI, is associated with COVID-19 prognosis, and taking care of such patients needs further awareness and investigations.

Patients with chronic kidney disease (CKD) require specialized management. However, the current situation of CKD management is unclear during the coronavirus disease 2019 (COVID-19) pandemic. We ai...

Objective: It is unclear whether aggressive treatment would benefit lupus nephritis (LN) with poor renal function, which has been excluded from most clinical trials. We aimed at demonstrating their clinicopathological features and prognosis.Methods: From August 2012 to December 2018, patients with active LN with poor renal function (estimated glomerular filtration rate (eGFR) between 15 and 59 mL/min/1.73 m²) receiving induction therapy were included. Complete response (CR) was defined as proteinuria <0.5 g/24 hours, while partial response (PR) was defined as ≥50% proteinuria reduction to subnephrotic levels (<3.5 g/24 hours), with (near) normal eGFR. The primary outcome was end-stage renal disease (ESRD). The significant variables were selected via the least absolute shrinkage and selection operator method to construct prediction models for ESRD and treatment response.Results: A total of 107 patients were included. At 6 months, 18.7%, 38.3% and 43.0% of patients achieved CR, PR and no response (NR), respectively. During a median follow-up of 60 months, 40.2% ended up with reduced renal function (eGFR <60 mL/min/1.73 m²) and 14.0% progressed to ESRD. The proportions of NR at 6 months were significantly higher in these patients compared with those with recovered renal function (p3 months (2.517, 1.012–7.226) and chronicity index (HR 1.757, 95% CI 1.371 to 2.414) predicted NR at 6 months (C-index 0.833, 95% CI 0.756 to 0.910).Conclusions: In patients with LN with poor renal function, no response at 6 months predicts a poor long-term renal outcome.

Dear Editor,The efficacy of hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) in correcting renal anemia, including in special populations, has been demonstrated in several randomiz...