BackgroundThe majority of cases of Dent’s disease are caused by pathogenic variants in the CLCN5 gene, which encodes a voltage-gated chloride ion channel (ClC-5), resulting in proximal tubular dysfunction. We present three members of the same family and one unrelated paediatric patient with the same insertion-deletion CLCN5 variant. The identification of these patients and positive familial segregation led to the re-classification of this variant from one of unknown significance to one of likely pathogenicity.Case presentationA 41 year old male presented with end stage kidney failure, proteinuria and haematuria. Whole genome sequencing identified an insertion-deletion variant in CLCN5, resulting in a missense change (c.1744_1745delinsAA p.(Ala582Lys)). His brother and nephew, who both exhibited renal impairment, haematuria, proteinuria, glycosuria and nephrocalcinosis, were found to have the same variant. In addition, genetic testing of an unrelated paediatric patient who presented with proteinuria and hypercalciuria, demonstrated the same variant.ConclusionsThe identification of this novel variant in four individuals with features of Dent’s disease, has led to the re-classification of the variant to one of likely pathogenicity.As a result, our patients and any future patients with the same variant can be offered a likely diagnosis, without the need for kidney biopsy, and their family members can be offered genetic screening.

Rituximab, a chimeric anti-CD20 monoclonal antibody, is an effective treatment for nephrotic syndrome. Hypokalemia is a rare adverse reaction among patients treated with rituximab although there have been extensive reports of acute and chronic adverse events with the administration of rituximab. We herein report two cases of symptomatic hypokalemia after intravenous rituximab administration in our center, to help health professionals consider the possibility of acute hypokalemia after rituximab administration, monitor potassium timely and develop an appropriate treatment plan.

BackgroundRecent developments in mass spectrometry (MS) have revealed target antigens for membranous nephropathy (MN), including phospholipase A2 receptor and exostosin 1/exostosin 2 (EXT1/2). EXT1/2 are known antigens of autoimmune disease-related MN, especially membranous lupus nephritis. We describe the case of an elderly man who developed nephrotic syndrome followed by progressive renal dysfunction.Case presentationA 78-year-old man presented with rapidly progressive renal dysfunction with proteinuria and hematuria. Three years previously, he had developed leg edema but did not receive any treatment. Laboratory tests showed elevated anti-nuclear antibody (Ab), anti-dsDNA Ab titer, and hypocomplementemia, indicating systemic lupus erythematous. Myeloperoxidase anti-neutrophil cytoplasmic Ab (ANCA) and anti-glomerular basement membrane (GBM) Ab were also detected. The renal pathologic findings were compatible with crescentic glomerulonephritis (GN), whereas non-crescentic glomeruli exhibited MN without remarkable endocapillary or mesangial proliferative change. Immunofluorescence microscopy revealed glomerular IgG, C3, and C1q deposition. All IgG subclasses were positive in glomeruli. Anti-PLA2R Ab in serum was negative. MS analysis was performed to detect the antigens of MN, and EXT1/2 was detected in glomeruli. Therefore, we reached a diagnosis of membranous lupus nephritis concurrent with both ANCA-associated vasculitis and anti-GBM-GN. The simultaneous occurrence of these three diseases is extremely rare.ConclusionsThis is the first report of EXT1/2-related membranous lupus nephritis concurrent with ANCA-associated vasculitis and anti-GBM-GN. This case demonstrates the usefulness of MS in diagnosing complicated cases of MN.

BackgroundExtraglomerular immune complex deposition is rare and only a few membranous nephropathy cases with tubular basement membrane deposits have been reported following allogeneic hematopoietic stem cell transplantation.Case presentationWe reported a 56-year-old man with increased serum creatinine after allogeneic hematopoietic stem cell transplantation who underwent a renal biopsy. Tubular interstitial nephritis was identified on light microscope. The unique histologic features were diffuse tubular basement membrane immune complex deposition detected by both immunofluorescence and electron microscopy, while the glomerular involvement was inconspicuous. The differential diagnosis from other forms of tubular basement membrane deposition is discussed.ConclusionDiffuse granular tubular basement membrane immune complex deposition with minimal glomerular involvement is also a manifestation of renal complication in hematopoietic stem cell transplantation recipient. However, the exact mechanism and target antigen remains unknown.

BackgroundNutcracker syndrome (NCS) caused by left renal vein (LRV) entrapment, is one of the most common causes of orthostatic proteinuria. In stereotype, orthostatic proteinuria is often accompanied by left renal vein obstruction and is found in young and underweight individuals. Here, we report a rare case with orthostatic proteinuria in an old obese female caused by a rare type of congenital inferior vena cava (IVC) interruption.Case presentationA 65-year-old obese woman, who suffered from fluctuated proteinuria, had been misdiagnosed as chronic glomerulitis for 30 years. Instead of having any sign of NCS, she had a unique type of IVC interruption. Most venous blood from infrarenal IVC and right kidney drained into her LRV, and then through the expanded communicating vessel, drained into the left ascending lumbar vein which extended as hemiazygos vein. To the best of our knowledge, this is one of the first cases reported of orthostatic proteinuria attributed to the subsequent hemodynamic irregularity caused by IVC interruption without nutcracker phenomenon.ConclusionAdult-onset orthostatic proteinuria is relatively rare, hard to be recognized and could be misdiagnosed as chronic glomerulonephritis. The case provided a novel differential diagnostic condition for those who suffered from fluctuated proteinuria of unknown causes.

BackgroundThe kidney is particularly vulnerable to toxins due to its abundant blood supply, active tubular reabsorption, and medullary interstitial concentration. Currently, calcium phosphate-induced and calcium oxalate-induced nephropathies are the most common crystalline nephropathies. Hyperoxaluria may lead to kidney stones and progressive kidney disease due to calcium oxalate deposition leading to oxalate nephropathy. Hyperoxaluria can be primary or secondary. Primary hyperoxaluria is an autosomal recessive disease that usually develops in childhood, whereas secondary hyperoxaluria is observed following excessive oxalate intake or reduced excretion, with no difference in age of onset. Oxalate nephropathy may be overlooked, and the diagnosis is often delayed or missed owning to the physician’s inadequate awareness of its etiology and pathogenesis. Herein, we discuss the pathogenesis of hyperoxaluria with two case reports, and our report may be helpful to make appropriate treatment plans in clinical settings in the future.Case presentationWe report two cases of acute kidney injury, which were considered to be due to oxalate nephropathy in the setting of purslane (portulaca oleracea) ingestion. The two patients were elderly and presented with oliguria, nausea, vomiting, and clinical manifestations of acute kidney injury requiring renal replacement therapy. One patient underwent an ultrasound-guided renal biopsy, which showed acute tubulointerstitial injury and partial tubular oxalate deposition. Both patients underwent hemodialysis and were discharged following improvement in creatinine levels.ConclusionsOur report illustrates two cases of acute oxalate nephropathy in the setting of high dietary consumption of purslane. If a renal biopsy shows calcium oxalate crystals and acute tubular injury, oxalate nephropathy should be considered and the secondary causes of hyperoxaluria should be eliminated.