Clinical Nephrology. Case Studies最新文献

Graft tolerance is a clinical state of absence of an immune response in the recipient toward a donor allograft without any exogenous immunosuppression. Although more prevalent in liver transplantation recipients, it has rarely been reported in renal transplant recipients. We present a 62-year-old deceased donor kidney transplant recipient who exhibited operational tolerance as they stopped immunosuppressant medications for more than 10 years and yet demonstrated stable graft function. Although various hypotheses, such as deletion, anergy, immunoregulation, and clonal exhaustion, have been experimentally validated, clinical "operational tolerance" of a renal allograft on a prolonged basis has been infrequently reported in the medical literature. This review intends to highlight possible etiologies and make clinicians aware of this possible rare condition to which more research is needed.

We performed a kidney biopsy in a 36-year-old man to evaluate microscopic hematuria and proteinuria. Light microscopy showed increased mesangial matrix and partial swelling of the glomerular basement membrane (GBM), and immunofluorescence showed positive staining only for C3. Immunoelectron microscopy showed that gold particle-labeled C3 was localized in the electron-dense and moderately electron-dense deposits shown by electron microscopy in the mesangium, the thickened GBM near the paramesangium, and the thickened distal portion of the GBM but was not localized in the non-thickened GBM. Gold-labeled immunoglobulin G, κ, and λ were not seen. C3 glomerulonephritis was more evident in gold-labeled electron microscopy, which further clarified the localization of C3 deposition.

Peritonitis is a common complication of peritoneal dialysis (PD) usually caused by skin-dwelling Gram-positive bacteria and Gram-negative bacteria colonizing the gut and urinary tract. Occasionally, uncommon bacteria can cause peritonitis in PD patients. We describe a case of Ralstonia mannitolilytica peritonitis in a 67-year-old woman who has been on PD for more than 10 years with no prior episodes of peritonitis. To our knowledge, this is the first reported case of Ralstonia peritonitis in the United States. She initially presented with abdominal tenderness, right flank pain, and cloudy output from her nephrostomy tube. PD fluid and urine cultures grew E. coli which responded to treatment. However, her symptoms recurred after completion of antibiotic therapy with PD fluid growing Ralstonia species. She again responded to intraperitoneal antibiotics but had recurrence of symptoms after the completion of her second course of antibiotics. PD fluid grew Ralstonia mannitolilytica resistant to the prior antibiotic regimen. The PD catheter was removed, and she was transitioned to hemodialysis. Subsequent treatment led to the resolution of her symptoms. Ralstonia species are Gram-negative bacteria that are prevalent in water supplies and can form biofilms. They have been known to cause infection particularly in neonates, immunocompromised patients, or patients in intensive care. In our patient, prior antibiotic treatment for E. coli peritonitis is likely to have contributed to the development of Ralstonia peritonitis. Clinical improvement after removal of the PD catheter revealed that seeding from the PD catheter was the likely culprit for the recurrent infections.

Synthetic cannabinoid (SCB) usage among children is a rapidly emerging public health concern in the United States. Acute kidney injury (AKI) is an uncommon manifestation of SCB usage, with acute tubular necrosis (ATN) as the predominant histology. Here we describe a 16-year-old adolescent who sustained severe non-oliguric AKI in association with SCB usage. Emesis, right flank pain, and hypertension were the presenting clinical features. There was no uveitis, skin rash, joint pains, or eosinophilia. Urinalysis showed absence of proteinuria or hematuria. Urine toxicology was negative. Renal sonogram showed bilateral echogenic kidneys. Renal biopsy demonstrated severe acute interstitial nephritis (AIN), mild tubulitis, and absence of ATN. AIN responded with pulse steroid followed by oral steroid. Renal replacement therapy was not required. Although the exact pathophysiology of SCB-associated AIN is not known, immune response elicited by the renal tubulointerstitial cells against the antigens present in the SCB is the most likely mechanism. A high index of suspicion for SCB-induced AKI is necessary in adolescents who present with AKI of unclear etiology.

Kidneys are commonly involved in systemic amyloidosis. Systemic AA amyloidosis is known to be associated with states of chronic inflammation such as autoimmune conditions, chronic infections, and malignancies. Obesity is increasingly recognized to be a risk factor for low-grade, chronic inflammation. We report a 48-year-old female with morbid obesity who presented with unexplained persistent mild kidney dysfunction and low-grade proteinuria. Attempt at evaluating the cause of kidney dysfunction included performing kidney biopsy despite technical challenges. Kidney biopsy showed AA amyloidosis with predominant vascular deposition, explaining the absence of nephrotic-range proteinuria. Evaluation for secondary causes of systemic AA amyloidosis was negative. While our patient was treated with sleeve gastrectomy for morbid obesity with reasonable response, it is likely that ongoing chronic inflammation, reflected by her laboratory markers, resulted in AA amyloidosis. Treatment with anakinra, an interleukin-1 antagonist, led to improvement in the laboratory markers in the next 6 months, and her kidney function remained stable. This report highlights an important cause of kidney dysfunction in morbid obesity, an atypical presentation of AA amyloidosis, and emphasizes the value of kidney biopsy in such patients.

We report a case of a 58-year-old woman presenting with symptoms of oliguria, fatigue, anorexia, constipation, hypovolemic signs, and laboratory tests showing severe hypokalemia (1.7 mEq/L), hyponatremia (120 mEq/L), high serum creatinine (SCr, 6.46 mg/dL) and urea (352 mg/dL). The patient had previously been diagnosed with chronic kidney disease (CKD), with SCr up to 2.58 mg/dL 1 year prior, and had in all her previous laboratory tests shown hypokalemia, which was treated with conservative measures and eplerenone despite low-normal blood pressure and normal heart function. A set of coordinated measures were applied to restore the potassium deficit, revert hypovolemic hyponatremia, and support renal function (including 4 dialysis sessions). In addition, a careful diagnostic approach revealed inappropriately high urine sodium and potassium losses, hypocalciuria, and hyperreninemic hyperaldosteronism leading to the diagnosis of Gitelman syndrome and hypokalemia-associated chronic tubulointerstitial nephropathy. Importantly, compliance with a simple set of instructions on high potassium and liberal sodium diet enabled the patient not only to remain euvolemic, free of symptoms, and with normal electrolytes, but also to recover a significant part of renal function and stabilize at an earlier CKD stage. Gitelman syndrome is a rare disorder that can be easily diagnosed and treated following simple measures; its early diagnosis is necessary to avoid life-threatening complications.

Introduction: Thrombotic microangiopathy (TMA) is characterized by microangiopathic hemolytic anemia and is associated with a variety of conditions and following hematopoietic stem cell transplantation. Chimeric antigen receptor T-cell (CAR-T) therapy is a novel immunotherapeutic approach using genetically modified autologous T cells. CAR-T therapy has been linked with injuries to vascular endothelium, but a direct association between CAR-T and TMA has not been reported.

Case reports: Two cases of TMAs following CAR-T treatment are reported here. In each case, clinical evidence of kidney injury, thrombocytopenia, and hemolytic anemia became apparent 2 - 3 months following CAR-T infusion. We describe the clinical course, management, and outcome of these experiences.

Discussion/conclusion: CAR-T cell therapy-associated TMA (CAR-T TMA) appear to be an entity that shares overlapping clinical features with transplant-associated TMA (TA-TMA). Based on our preliminary clinical observations, we discuss the best clinical diagnosis/classification criteria, underlying pathophysiology, and the implication of the apparently self-limiting course. With increasing use of CAR-T cell treatment in hematologic malignancies, systematic studies will be necessary to improve management of CAR-T TMA.

Icodextrin use during the long dwell of a peritoneal dialysis (PD) regimen is commonly used to increase ultrafiltration. Its use may cause a mild and clinically insignificant degree of hyponatremia. We describe a patient who was admitted twice to our medical center on an atypical continuous ambulatory peritoneal dialysis (CAPD) regimen utilizing solely icodextrin with 2 exchanges (12-hour dwells). On both admissions, he had hyperosmolar hyponatremia in the 120-mmol/L range with a large osmolal gap. After icodextrin was stopped and his PD prescription was switched to dextrose solutions, both hyponatremia corrected and the osmolal gap quickly disappeared. The accumulation of osmotically active solute in extracellular fluids results in efflux of water from the cellular compartment and produces both hyponatremia and hypertonicity [1]. This tonic effect occurs most frequently with hyperglycemia, but other substances can also cause this, including mannitol, sorbitol, glycine, and maltose [1, 2]. In this report, we present a patient with end-stage renal disease (ERSD) on an atypical off-label PD regimen utilizing solely icodextrin solutions who developed hyperosmolar hyponatremia in the 120-mmol/L range, with a large osmolal gap. This appeared to be due to absorbed metabolites of icodextrin, mainly maltose.

Tuberous sclerosis complex (TSC) is a genetic disease characterized by the growth of numerous noncancerous tumors in many parts of the body mainly the skin, brain, kidneys. The prevalence of the disease is estimated to be 7 - 12 in 100,000. We report the cases of two black African women diagnosed with TSC at age 25 and 54. They both had renal angiomyolipoma, facial angiofibroma and diffuse hypochromic macules. The older patient remained stable for the 11 years following her diagnosis. But, in the second patient, the disease was more severe with a giant angiomyolipoma, complicated by renal intracystic hemorrhage leading to the patient's death 1 month after diagnosis. Renal involvement can be life-threatening in patients with TSC. The risk of fatal bleeding increases with the size of the tumor. The mTOR inhibitors and angioembolization can improve the prognosis of this disease.

Dent's disease is an X-linked recessive disease characterized by proximal tubulopathy with low-molecular weight proteinuria, hypercalciuria, nephrolithiasis, nephrocalcinosis, and kidney failure. It is mainly caused by mutations in the CLCN5 or OCRL1 genes, and only ~ 250 families have been identified with these mutations. We present a 31-year-old male referred to a nephrology consultation due to elevated serum creatinine and a history of nephrolithiasis. Complementary evaluation revealed protein/creatinine ratio of 1.9 g/g and albumin/creatinine ratio of 0.5 g/g, hypercalciuria and medullary nephrocalcinosis. These findings raised the suspicion of Dent's disease, which was confirmed by genetic testing. A missense mutation in the CLCN5 gene (c.810C>G, p.(Ser270Arg)), not previously reported in populational databases, was identified. During the evaluation of the patient, it came to our attention that a first-degree male cousin was being followed in our kidney transplantation unit. Given the unknown etiology of his chronic kidney disease, genetic testing was performed, identifying the same mutation. This case highlights the importance of considering the diagnosis of Dent's disease in the setting of a male patient with chronic kidney disease of unknown etiology, low-molecular-weight proteinuria, hypercalciuria, and nephrocalcinosis. Despite progression to end-stage kidney failure in a significant portion of male patients, there are no reports of recurrence after kidney transplantation.