BACKGROUND:Myeloma cast nephropathy (CN) is a severe complication of multiple myeloma and a frequent cause of dialysis-dependent acute kidney injury (AKI). High circulating free light chains (FLC) contribute to tubular injury, and strategies aimed at accelerating their reduction have been proposed. Medium cut-off (MCO) membranes allow enhanced clearance of middle molecules, including FLC. Clinical data regarding their implementation in routine practice remain limited. The aim of this study was to describe our institutional experience following the introduction of MCO hemodialysis in patients with dialysis-dependent CN. MATERIALS AND METHODS:We conducted a retrospective single-center case series including consecutive patients treated between February 2024 and December 2025. Eligible patients had dialysis-dependent AKI due to presumed or biopsy-proven CN and were managed according to a predefined protocol combining anti-myeloma therapy and intensive MCO hemodialysis (Theranova 500), consisting of eight 6-hour sessions within the first 10 days when clinically feasible. Serum FLC levels were measured before each session. RESULTS:Six patients were included. Baseline FLC levels ranged from 1,550 to 30,000 mg/L. A marked early decline in circulating FLC was observed during the intensive MCO phase, with 4 patients achieving > 80% reduction. Treatment interruptions due to clinical instability, frequently associated with infectious complications, occurred in several cases. Renal trajectories were heterogeneous, and dialysis independence was achieved in 3 patients. CONCLUSION:This case series describes the real-world implementation of MCO hemodialysis in dialysis-dependent CN. Although substantial early FLC reduction was observed, renal recovery varied and appeared to be influenced by multiple clinical factors.
Mesenteric cysts are uncommon benign abdominal lesions with no specific clinical features. Their occurrence during hemodialysis is exceptional. We report the case of a 22-year-old patient who had been treated with peritoneal dialysis for 2 years and was subsequently transferred to hemodialysis because of refractory peritonitis. Three years later, he presented with a progressive abdominal distension caused by a large mass extending from the epigastric to the pelvic region. Exploratory laparoscopy revealed a giant cystic lesion occupying the entire peritoneal cavity. Complete surgical excision was performed. Histopathological examination confirmed a benign mesenteric cyst of mesothelial origin. This rare complication may be associated with previous peritoneal dialysis, recurrent peritonitis, and a chronic inflammatory state.
Metformin-associated lactic acidosis (MALA) is a rare phenomenon mostly described in the setting of impaired renal elimination or following an acute overdose. While metformin is first-line treatment for type 2 diabetes mellitus, glucagon-like peptide-1 (GLP-1) receptor agonists and glucose-dependent insulinotropic polypeptide (GIP) and GLP-1 dual receptor agonists are frequent add-on agents. Both classes of medications share common gastrointestinal adverse reactions, including decreased appetite, nausea, vomiting, and abdominal pain. We present a series of four critically ill patients with type 2 diabetes mellitus on high-dose metformin who presented with severe MALA following the introduction or dose escalation of a GLP-1 or GIP/GLP-1 dual receptor agonist, or during an acute gastrointestinal illness while also on a maintenance dose of a GLP-1 receptor agonist, requiring acute renal replacement therapy. Prudence must be exercised when co-prescribing these 2 classes of medications with close monitoring of kidney function, possible reduction in metformin dose, and emphasis on sick day rule teaching.
Syndromic associations of kidney and ophthalmological diseases are not typical in the young adult. The most common kidney manifestations are malformations of the genitourinary apparatus, while some syndromes can also present with kidney parenchymal disease. We report on a 51-year-old woman evaluated in the nephrology clinic for 12 months due to abnormal kidney function. She had been diagnosed with Usher syndrome due to the development of retinitis pigmentosa and sensorineural hearing loss in the last 20 years, without genetic testing. She had a family history of parental consanguinity, and disperse cardiac disease, congenital malformations, and congenital deafness. For chronic kidney disease of unknown etiology, a kidney biopsy was performed which revealed focal segmental glomerulosclerosis (FSGS) of the perihilar variant. This diagnosis prompted genetic testing that identified a mutation on gene SDCCAG8: c.397G>T, known for causing Bardet-Biedl type 16 and Senior-Løken type 7 syndromes. This case of perihilar FSGS is atypical in the setting of a ciliopathy and absence of metabolic or cardiovascular risk. Though urinary tract malformations and kidney disease can be expected, glomerular disease is not described in the literature. Genetic syndromic diagnoses require genetic screening due to the overlap of different symptoms and variable penetrance. The diagnosis of genetic diseases requires a high degree of suspicion, especially when the phenotype of the kidney disease is unusual. Identification of variants can help identify individuals who can benefit from genetic counseling.
BACKGROUND:17q12 microdeletion syndrome is a rare genetic disorder distinguished by diabetes, urogenital abnormalities, pancreatic hypoplasia, and neuropsychiatric developmental anomalies, with hyperuricemia being an infrequent occurrence. We present a unique case of 17q12 microdeletion, encompassing 17 protein-coding genes such as HNF1B, AATF, and DDX52 (3A:0), marking the first documented instance globally. CASE REPORT:An 18-year-old female patient was hospitalized due to persistent right upper abdominal pain for more than a month. She exhibited a normal body mass index and no familial medical history. Biochemical analysis indicated liver impairment, hyperlipidemia, hypomagnesemia, hyperuricemia, and glucose intolerance. Renal ultrasound displayed numerous renal cysts, while a liver biopsy confirmed the presence of non-alcoholic fatty liver disease. Given the early onset of metabolic syndrome, whole-exome sequencing (WES) was conducted on the patient and her parents. RESULTS:By WES and copy number variation verification, the patient was identified as having a de novo heterozygous deletion of one copy in the 17q12 region (34807034-36285028), encompassing 17 protein-coding genes including HNF1B, AATF, and DDX52 (3A:0). Tubulointerstitial lesions are the predominant feature of HNF1B-related renal disease, with hyperuricemia showing limited predictive value despite its common occurrence. Hypomagnesemia is a significant clinical indicator in HNF1B mutation-related conditions. CONCLUSION:Hyperuricemia, hypomagnesemia, and multiple renal cysts can manifest as renal symptoms of the microdeletion in the 17q12 region, with the spectrum of extra-renal manifestations continually expanding. For young patients exhibiting the above metabolic issues, WES is recommended for precise diagnosis.
Nail-patella syndrome (NPS) is an uncommon autosomal dominant condition marked by nail dysplasia, skeletal abnormalities, and variable renal manifestations, resulting from mutations in the LMX1B gene. We report a rare case of a 23-year-old male presenting with nephrotic-range proteinuria, characteristic skeletal manifestations of NPS, and a family history of renal failure. Genetic testing identified a previously unreported heterozygous missense variant in the homeodomain of LMX1B (c.791A>C; p.Gln264Pro), supporting its pathogenicity. The absence of patellar hypoplasia in our patient highlights the phenotypic variability of NPS. This case reinforces the importance of detailed physical examination and targeted genetic testing in diagnosing nephrotic syndromes.
IgA nephropathy (IgAN) is the most common primary glomerulonephritis, characterized by mesangial IgA immune complex deposition, potentially leading to chronic kidney disease. Idiopathic erythrocytosis, an unexplained elevation of red blood cell mass, has rarely been reported in association with IgAN. We present a systematic literature review and a new case highlighting the temporal relationship between IgAN and idiopathic erythrocytosis. A PubMed search identified four relevant studies detailing IgAN accompanied by unexplained erythrocytosis. The literature suggests an association predominantly observed in male patients, typically concurrent with or subsequent to an IgAN diagnosis. In our case, however, idiopathic erythrocytosis was detected 2 years prior to the onset of clinical signs of IgAN. The patient, initially treated with phlebotomy, presented 2 years later with significant proteinuria, leading to a renal biopsy confirming IgAN. This temporal progression raises the hypothesis that polymeric IgA1 immune complexes may influence erythropoiesis prior to evident renal involvement. Clinicians should consider underlying glomerular disease in patients with unexplained erythrocytosis, even in the absence of overt renal symptoms.
T-lymphoblastic lymphoma/leukemia (T-LBL) is a rare and aggressive hematologic malignancy characterized by a neoplastic proliferation of immature T lymphocytes that is restricted to nodal/extra-nodal sites with minimal involvement of bone marrow. While T-LBL is the second most frequent subtype of pediatric non-Hodgkin lymphoma, primary renal involvement in T-LBL is exceedingly rare and can pose a significant diagnostic challenge. We present the case of an 11-year-old male who initially presented with new-onset seizure, hypertensive crisis, and acute renal failure. Renal ultrasounds demonstrated enlarged kidneys with loss of corticomedullary differentiation suggestive of medical renal disease. A kidney biopsy was performed, revealing an atypical interstitial T-cell infiltrate with diffuse expression of CD4, CD8, and TdT, raising concern for T-cell acute lymphoblastic lymphoma (instead of leukemia) (T-ALL/LBL). A subsequent bone marrow biopsy was negative, and no other sites of involvement were identified on PET/CT, so chemotherapy was deferred until the diagnosis could be confirmed. The patient re-presented 2 months later with visual changes and diffuse leptomeningeal enhancement on MRI. Repeat kidney biopsy with flow cytometry demonstrated a population of aberrant T cells with CD4/CD8 co-expression. A repeat bone marrow biopsy contained < 1% blasts, and no aberrant lymphocytes were detected in peripheral blood. CT scan revealed new retroperitoneal adenopathy with infiltrative disease involving kidneys, pancreas, adrenal glands, and liver, consistent with stage IV T-LBL.Kidney involvement in acute LBL is uncommon, and renal failure due to leukemic infiltration is rarely reported. This case underscores the importance of performing kidney biopsies in cases of unexplained acute renal failure and considering lymphoma in the differential for interstitial nephritis, even in the absence of abnormal hematological findings.
Renal cortical necrosis (RCN) is a rare but severe cause of acute kidney injury primarily observed in obstetric complications. We herein present a case of RCN in a 32-year-old Mongolian primigravida transferred to our hospital with uncontrolled massive postpartum hemorrhage. Contrast-enhanced computed tomography revealed ongoing uterine hemorrhage, prompting endovascular intervention for control. It also showed the loss of cortical perfusion in the kidneys, while preserving medullary blood flow, which is consistent with RCN. The patient remained anuric from transfer and required continuous hemodiafiltration followed by intermittent hemodialysis. Renal biopsy on day 23 revealed coagulative necrosis in glomeruli and tubules in the outer cortex, consistent with RCN, while glomeruli in the deeper cortex were spared. Glomeruli in the outer cortex displayed glomerular paralysis. The patient transitioned to peritoneal dialysis (PD) to facilitate infant care at home. Over 6 months, renal function improved, allowing dialysis discontinuation. Four years post-discharge, she remains free of renal replacement therapy, with serum creatinine of 2.67 mg/dL. The present case highlights the potential for gradual renal function improvement in RCN through the recovery of residual nephrons. PD may be a promising modality for patients with RCN.
Kimura disease (KD) is a chronic benign granulomatous disease. Approximately 20% of patients with KD have renal disease. Membranous nephropathy (MN) is one of the main renal pathologies in KD; however, the underlying mechanism remains unknown. We herein present a 28-year-old male diagnosed with KD after biopsy of a left lower eyelid mass 11 years earlier. He visited our hospital with edema in the lower legs and scrotum. A blood test showed a serum creatinine level of 0.95 mg/dL and serum albumin level of 0.9 g/dL. Urinalysis revealed heavy proteinuria with mild hematuria. Renal biopsy showed spike formation by PAM staining and granular deposits of IgG and C3 in the glomerular basement membrane by direct immunofluorescence microscopy (IF). Electron microscopy revealed subepithelial electron-dense deposits (EDD). IF staining for the phospholipase A2 receptor (PLA2R) was positive in the glomerular basement membrane, leading to a diagnosis of PLA2R-associated MN. Our literature review on MN in KD included 14 cases, all of which exhibited subepithelial EDD, while subendothelial EDD was absent in 10. PLA2R staining was positive in 2 of the 3 cases examined. The results of this case and the literature review suggest the involvement of autoantibodies against podocyte antigens in the pathogenesis of MN in KD. Further studies are needed on these antigens.
Bartter syndrome (BS) is a rare autosomal recessive disorder characterized by inherited salt-losing tubulopathies. Distinguished into six types, each associated with specific genetic mutations, type II is particularly rare in adults and typically presents early. This report documents a rare case of an adult diagnosed with type II Bartter syndrome that progressed to end-stage kidney disease (ESKD) and underwent successful kidney transplantation, marking it a first of its kind in India and only the second globally. The patient, diagnosed in adulthood, experienced a delayed onset of symptoms, including uremia, hypocalcemia, and medullary nephrocalcinosis, which progressed to ESKD. Genetic testing confirmed a homozygous missense mutation in the KCNJ1 gene. After prolonged hemodialysis, a kidney transplant from a deceased donor resulted in successful graft function and symptom resolution. This case underlines the phenotypic variability of Bartter syndrome and provides critical insights into managing severe, late-onset cases through transplantation.
INTRODUCTION:Oxalate nephropathy (ON) is a rare condition caused by calcium oxalate crystal deposition in renal tubules, leading to acute kidney injury (AKI), chronic kidney disease (CKD), or both. The etiologies of ON are divided into two main categories: primary and secondary. Linaclotide is used for the constipation subtype of irritable bowel syndrome (IBS-C), which is not reported to precipitate ON. CASE PRESENTATION:We report a unique case of linaclotide-precipitated ON in a 50-year-old female with predisposing comorbidities. The patient developed severe AKI (creatinine 8.37 mg/dL) 3 months after starting linaclotide for IBS-C. Symptoms included fatigue, flank pain, and pale stools. Kidney biopsy confirmed ON. Linaclotide was discontinued, and supportive treatment led to significant renal recovery, with creatinine returning to baseline (0.92 mg/dL) within 2 months. DISCUSSION:This case highlights linaclotide's potential to precipitate ON in patients with risk factors such as malabsorption and dehydration. Secretory diarrhea caused by linaclotide may increase intestinal oxalate absorption, triggering hyperoxaluria. While not inherently nephrotoxic, linaclotide may exacerbate existing susceptibilities. CONCLUSION:Linaclotide can contribute to ON in predisposed patients. Clinicians should consider medication history and risk factors in unexplained AKI and pursuing kidney biopsy for diagnosis.
INTRODUCTION:The sudden onset of nephrotic syndrome (NS) and acute interstitial nephritis (AIN) seems to be an uncommon but distinct nonsteroidal anti-inflammatory drug (NSAID)-related renal syndrome. CASE PRESENTATION:We present such a case in a patient who took a "magic pill" for gout. Renal biopsy revealed minimal change disease (MCD), acute interstitial nephritis (AIN), severe acute tubular injury (ATI), and IgA nephropathy (IgAN). He was treated with an aborted course of high-dose prednisone, with complete resolution of his renal diseases. The pathologic finding of the combination of MCD and AIN raised the possibility of a drug effect. One of the pills was analyzed and found to be primarily composed of diclofenac. Initially, we considered IgAN a bystander, considering primary IgAN is the most common glomerulonephritis worldwide, especially in Asians and Hispanics. However, the complete resolution of urinary findings after discontinuation of the pill followed by a few days' treatment with prednisone, together with no recurrence of the kidney disease over 6 years, made us speculate that IgAN may have also been triggered by diclofenac. CONCLUSION:We presented a case of AIN, MCD, and IgAN associated with diclofenac masquerading as a "herbal" medicine. The cause was suggested by pathology and confirmed with high-resolution liquid chromatography mass spectrometry testing of the pills. A history of NSAID use should be diligently sought in any patient who presents with NS and AIN. In addition, this is the first report of IgAN possibly induced by NSAID without recurrence after 6 years' follow-up.
INTRODUCTION:Ankylosing spondylitis (AS) is a chronic, progressive inflammatory disease that primarily affects the spine and sacroiliac joints. In recent years, biologic agents have gained increasing popularity in the treatment of AS due to their high targeting specificity and favorable side effect profiles. Among these, secukinumab has emerged as an effective treatment option. However, the safety and efficacy of secukinumab in patients undergoing hemodialysis has not yet been thoroughly verified. CASE REPORT:Here, we report the successful treatment of AS with secukinumab in a 36-year-old male patient undergoing hemodialysis. The patient presented with recurrent lumbosacral pain and tested positive for HLA-B27. After treatment, significant improvements were observed in both the imaging characteristics of the synovial joints and the patient's symptoms. CONCLUSION:This case suggests that secukinumab may have a positive effect on AS in patients on hemodialysis, without apparent adverse effects.
Karyomegalic interstitial nephritis (KIN) is a rare hereditary form of chronic interstitial nephritis that was first described over 50 years ago. It is characterized by karyomegalic tubular epithelial cells and progressive chronic kidney disease, often leading to end-stage renal disease by the fifth decade of life. Recent studies have identified FAN1 mutations as a key genetic contributor, with additional associations to environmental factors and toxic exposures, such as ochratoxin A, alkylating agents, and heavy metals, which may act as potential triggers of the disease. We present a detailed analysis of KIN cases, highlighting genetic diversity, clinical manifestations, and management challenges, complemented by a comprehensive review of the literature.
Adenine phosphoribosyltransferase (APRT) deficiency is a rare autosomal disorder with extremely variable presentation. The disease spectrum ranges from completely asymptomatic to 2,8-dihydroxyadenine (DHA) stones to massive deposition of DHA crystals leading to DHA crystalline nephropathy. We report a case of a 45-year-old woman who presented with acute kidney injury and recurrent vomiting. Kidney biopsy revealed precipitation of brown crystals in tubular lumina with acute tubular injury with characteristic birefringence on polarizing light, confirming the unexpected diagnosis of DHA crystalline nephropathy. She was started on a xanthine oxidase inhibitor which resulted in an improvement of kidney function. This case highlights the fact that APRT deficiency can have varied presentations and is an important hereditary cause of crystalline nephropathy.
Renal oxalosis occurs from supersaturation of the urine with oxalate in the presence of calcium, resulting in deposition of calcium oxalate crystals within renal tissue and, consequently, progressive renal disease. One of the causes of secondary hyperoxaluria is a high intake of vitamin C, which exceeds the renal excretion capacity, and can induce renal oxalosis. We present a case involving a 67-year-old patient with chronic kidney disease and proteinuria, associated with secondary hyperoxaluria and renal oxalosis, who reported prolonged, excessive intake of vitamin C supplements. The patient presented with a gradual worsening of his renal function and proteinuria during the last 6-month period, after an episode of SARS-CoV-2 infection. The kidney biopsy revealed calcium oxalate crystals within the renal tissue. Thorough investigation and history-taking revealed a substantial increase in vitamin C supplementation during the SARS-CoV-2 infection (up to 3 g daily), indicating secondary hyperoxaluria as the causative factor. Overall during the pandemic, supplement consumption dramatically increased and patients were not adequately informed about the risks of various over-the-counter products. Excessive intake of vitamin C, popularized for its supposed health benefits, can lead, among others, to secondary hyperoxaluria and renal oxalosis. Prompt recognition is pivotal to initiate management and to prevent irreversible kidney damage.
INTRODUCTION:Thrombotic microangiopathy (TMA) is a pathological description which clinically presents with thrombocytopenia, microangiopathic hemolytic anemia (MAHA), and organ dysfunction. The etiology of TMA is broadly classified into four categories: primary hereditary, primary acquired, secondary, and infection associated. H1N1 influenza is a rare etiology of complement-mediated TMA (CM-TMA) with there being under 30 cases reported to date, and its odd presentation with hemoptysis making it a challenge to diagnose. CASE PRESENTATION:We present a case of a Caucasian female in her 20s presenting to the hospital with a viral prodrome in setting of a new acute kidney injury (creatinine 8.2 mg/dL), thrombocytopenia (platelet count 14,000/mm3), and H1N1 influenza positive. She developed hemoptysis the next day, with no respiratory distress. Rheumatology work-up for antineutrophilic cytoplasmic antibodies (ANCA), anti-glomerular basement membrane (anti-GBM), and antiphospholipid syndrome (APS) antibodies was negative. CT chest was also negative for pulmonary hemorrhage. Plasma exchange was started empirically until ADAMTS13 activity returned normal (120%), and she was further commenced on eculizumab after an atypical hemolytic uremic syndrome (aHUS)/TMA/Complement 3 Glomerulopathy (C3G) gene panel was sent. Molecular studies revealed a splice site variant of MCP/CD46 gene, which was reiterated on a renal biopsy. The patient was counselled on the genetic results, including predisposition to future events and the importance of long-term eculizumab treatment. DISCUSSION:CM-TMA is a consequence of alternative pathway dysregulation, commonly associated with genetic mutations which could phenotypically be unmasked by infections, such as influenza virus. CONCLUSION:Our case highlights the importance of keeping a broad differential beyond classic pulmonary-renal syndromes in patients presenting with hemoptysis and TMA, while understanding the pathophysiology of infections unmasking genetic mutations in CM-TMA. .
Thromboembolic events are among the most serious, yet rare complications of nephrotic syndrome. While peripheral venous thrombosis and pulmonary embolism are the most common, superior mesenteric artery thrombosis is a rare but life-threatening occurrence. We present a case of severe cytomegalovirus (CMV) infection complicated by congenital nephrotic syndrome, leading to mesenteric ischemia.
