Preeclampsia accounts for the majority of nephrotic syndrome in pregnancy. However, primary renal diseases, although not as common, can also be the cause. The authors report a case of a 33-year-old pregnant woman at 22weeks of gestation who presented with significant proteinuria, hypoalbuminemia, hyperlipidemia and discrete pitting edema. After the initial workup, a kidney biopsy was performed to diagnose minimal change disease (MCD), which revealed extensive podocyte foot process effacement. Treatment with IV methylprednisolone followed by oral prednisone led to remission, but a relapse occurred at 37weeks of gestation. Labor was induced due to oligohydramnios with fetal growth restriction and a female hypotrophic neonate was delivered. Later on, the neonate developed sepsis and was successfully treated. Postpartum, the mother acquired a steroid resistance, and tacrolimus was used to achieve complete remission. In this case report,we emphasize the importance of kidney biopsy in adequately diagnosing primary renal diseases, even in pregnancy. Thisgreatly helps clinicians in choosing the appropriate therapy for the patient, leading to disease remission.

This case report presents a 57-year-old Japanese woman with mild COVID-19 who developed severe symptomatic hyponatremia and altered consciousness, notably without pneumonia or central nervous system infection. Initial findings, including low plasma osmolality, high urine osmolality, and elevated IL-6 levels, suggested that the syndrome of inappropriate antidiuretic hormone secretion (SIADH) was the primary cause of her hyponatremia. While initial saline infusion offered temporary symptom relief, sodium levels remained unstable, leading to intermittent steroid therapy. Her improvement with steroids, alongside additional hormonal testing, raised the possibility of partial adrenal insufficiency as a complicating factor. Although secondary adrenal insufficiency in COVID-19 cases has been previously reported, its exact contribution to hyponatremia remains unclear. This case underscores the diagnostic complexities in managing hyponatremia associated with COVID-19, as SIADH is often the leading cause but may not fully explain persistent cases unresponsive to standard treatments. The report also emphasizes the importance of considering adrenal insufficiency in similar cases, particularly given COVID-19's potential impact on the hypothalamic-pituitary-adrenal axis. This case highlights the need for further research into COVID-19's effects on hormonal regulation, as such disruptions may play a key role in COVID-19-related electrolyte imbalances.

A 61-year-old woman with a 10-year history of type 1 diabetes mellitus was referred to our nephrology department due to rapid kidney function deterioration. Despite good blood glucose control, her serum creatinine (Cr) concentration rose from 0.77mg/dL to 2.40mg/dL over one year. She had microscopic hematuria for several years, and an increase in urinary protein was observed over the past year. One month before the onset of kidney function exacerbation, she received the fourth vaccination against SARS-CoV-2. At referral, her urinary examination showed proteinuria of 4.73g/g Cr and microscopic hematuria. MPO-ANCA, PR3-ANCA, and anti-basal membrane antibodies were negative. A kidney biopsy revealed IgA nephropathy demonstrating focal mesangioproliferative glomerulonephritis with cellular crescents (M0E1S1T0-C1). The patient underwent six courses of intravenous cyclophosphamide administration in addition to steroid pulse therapy. One year after starting the treatment, her serum Cr improved to approximately 2mg/dL, and urinary protein decreased to 0.6g/g Cr.

Mitochondrial diseases (MDs) are inherited metabolic disorders that affect multiple organ systems, including the kidneys. Variability in disease onset and phenotypic expression, combined with the absence of specific kidney pathological findings, pose significant challenges in diagnosing MD. Consequently, many undiagnosed cases of MD may exist among patients undergoing dialysis. No effective treatment for mitochondrial nephropathy has been established. We report the case of a 27-year-old female patient who presented with leg edema, nephrotic range proteinuria attributed to focal segmental glomerulosclerosis, and bilateral sensorineural hearing loss. Immunosuppressive therapy failed to achieve remission, resulting in progressive kidney function decline and eventual end-stage kidney disease. At hemodialysis initiation, worsening atypical cardiac function and hypertrophy prompted genetic testing, which identified an MT-TL1 m.3243 A>G mutation and confirmed the diagnosis of MD. After hemodialysis initiation, the patient experienced persistent fatigue and decreased physical activity levels despite dry weight management. Suspected stroke-like symptoms prompted the initiation of taurine supplementation, which significantly improved headache severity, cardiac function, and physical activity levels. This case highlights the therapeutic potential of taurine supplementation in patients with MD undergoing dialysis and the importance of maintaining clinical vigilance for MD across all stages of chronic kidney disease, even without characteristic renal pathological findings of mitochondrial nephropathy.

Although the coronavirus disease 2019 (COVID-19) vaccine has been proven to be effective and safe in most adults and children, various diseases, including IgA nephropathy, sometimes occur as an adverse effect. We herein describe a case of IgA nephropathy in a 16-year-old, male patient with persistent kidney dysfunction following COVID-19 vaccination and present the clinicopathological course of the disease. The patient presented to the outpatient clinic with a history of gross hematuria 6days after receiving the COVID-19 vaccine. Prior to the current presentation, he was being examined regularly at an outpatient clinic for asymptomatic hematuria. His mother had received a diagnosis of IgA nephropathy, and his younger brother had received a diagnosis of asymptomatic hematuria. A blood test of this patient demonstrated elevated serum creatinine, and IgA nephropathy was pathologically diagnosed (Oxford classification M0E1S1T0C1). Prednisolone and immunosuppressants were administered promptly to treat the decreased kidney function and the pathology. Nevertheless, the failure of his kidney function to recover to the state it was in prior to this episode may have led to the formation of chronic lesions, causing irreversible kidney tissue damage. Some patients with IgA nephropathy, asymptomatic hematuria or a family history of kidney-related symptoms may experience kidney dysfunction after COVID-19 vaccination and require prednisolone or immunosuppressive therapy to stem the progressive deterioration of their kidney function. Prior to receiving the COVID-19 vaccine, patients with any of these conditions should be provided with an appropriate explanation of the risks and be asked for their consent to be vaccinated.

Autosomal dominant polycystic kidney disease (ADPKD), the most prevalent inherited kidney disorder, progresses inexorably to end-stage kidney disease (ESKD) with the vasopressin V2-receptor antagonist tolvaptan serving as a primary treatment option since 2014. While dapagliflozin, a sodium-glucose cotransporter-2 (SGLT2) inhibitor, was approved for treating chronic kidney disease in August 2021, its renoprotective effects in ADPKD remain uncertain due to potential vasopressin stimulation. We evaluated four Japanese ADPKD patients receiving combination therapy with tolvaptan and dapagliflozin for over two years. A 74-year-old woman (Mayo Class 1D, CKD stage 4) showed improved estimated glomerular filtration rate (eGFR) decline from - 1.39 to - 0.66mL/min/1.73m2/year. A 62-year-old woman (Mayo Class 1B, CKD stage 3b) demonstrated eGFR decline improvement from - 1.02 to - 0.66mL/min/1.73m2/year. A 39-year-old man (Mayo Class 1C, CKD stage 3a) exhibited significant improvement from - 5.00 to - 1.35mL/min/1.73m2/year. A 45-year-old woman (Mayo Class 1D, CKD stage 3b) showed marked improvement from - 14.12 to - 0.22mL/min/1.73m2/year. While eGFR decline decelerated in the control group, the combination therapy group showed more pronounced improvements. Height-adjusted total kidney volume (htTKV) in the group combination therapy showed variable responses: two patients experienced volume increases (+ 4.03%, + 3.65%/year), while two showed decreases (- 0.45%, - 3.65%/year). These cases suggest potential renoprotective benefits from combining tolvaptan and dapagliflozin in ADPKD patients. Careful monitoring of renal cyst enlargement is warranted with concurrent dapagliflozin use. Further research is needed to confirm these preliminary findings and establish optimal patient selection criteria for combination therapy.

An 18-year-old female presented with palpable purpura nine months before her hospital admission, which first appeared 1month after receiving a COVID-19 vaccine and recurred intermittently. One month prior to admission, she developed macrohematuria, abdominal pain, and a loss of appetite. Occult blood in urine had been noted during high school health check-ups. Upon admission, she continued to have macrohematuria, along with renal dysfunction and a nephritic urinalysis, serum myeloperoxidase-anti-neutrophil cytoplasmic antibodies (MPO-ANCA) positivity. A renal biopsy revealed crescentic glomerulonephritis with mesangial and endocapillary hypercellularity, and dominant IgA deposition and electron-dense deposits in the mesangial regions. The diagnosis was IgA nephropathy (IgAN) or IgA vasculitis with nephritis (IgAVN), with a possible overlap of MPO-ANCA-associated glomerulonephritis. Treatment began with methylprednisolone pulse therapy and prednisolone. After the diagnosis, rituximab (RTX) and avacopan were added to the regimen. Within two months, renal function, hematuria, and MPO-ANCA levels had normalized, and proteinuria was almost fully resolved by 13months. If IgAN/IgAVN and ANCA-associated vasculitis were indeed triggered by the COVID-19 vaccination in this case, it is plausible that both conditions share similar pathologic mechanisms. This case emphasizes the need for a reliable laboratory method to detect pathogenic ANCA to guide both induction and maintenance therapy. Further investigation into the effectiveness of the ANCA-associated glomerulonephritis treatment protocol including corticosteroids, RTX, and avacopan in managing crescentic IgAN/IgAVN could offer valuable insights into improving patient care.

A middle-aged woman was found to have proteinuria during a health check-up. About sixteen months later, she was diagnosed with stage IIA invasive ductal carcinoma of the right breast. Her proteinuria progressed to nephrotic syndrome with significant hematuria. Hormone therapy was initiated for her estrogen and progesterone receptor-positive breast cancer. A kidney biopsy performed 47days after starting the therapy revealed an IgA-dominant membranoproliferative glomerulonephritis-like pattern of injury. Electron microscopy showed subendothelial-dominant electron-dense deposits (EDD), with small amounts of mesangial EDD and a single occurrence of subepithelial hump-like EDD, along with occasional mesangial interpositions. Similar pathology can be caused by IgA vasculitis with nephritis, IgA-dominant infection-associated glomerulonephritis, and liver disease-associated glomerulopathy, but all of these were ruled out. The deposited IgA was found to be galactose-deficient IgA1. Thus, IgA nephropathy with glomerular capillary IgA deposition was considered. She underwent a right partial mastectomy and sentinel lymph node biopsy in the right axilla 75days after starting hormone therapy, followed by adjuvant radiation. Proteinuria and hematuria tended to decrease after the treatment, and this trend continued even after corticosteroid therapy for glomerulonephritis, which was administered 156days after starting hormone therapy. Approximately 15months after starting hormone therapy, her proteinuria had reduced to around 1.0g/g of creatinine, and her hematuria was negative. IgA nephropathy with glomerular capillary IgA deposition is known to be resistant to corticosteroid therapy. The favorable clinical course of the rare glomerulopathy following breast cancer treatment suggested a diagnosis of paraneoplastic glomerulopathy secondary to breast cancer in our patient.

Malignant hypertension with renal thrombotic microangiopathy is a rare yet serious cause of acute kidney injury (AKI). Patients are often treated with antihypertensive therapy; however, managing their blood pressure is complex, with targets for initial treatment unclear. We report on a 55-year-old male with severe hypertension (blood pressure 210/140mmHg), AKI (serum creatinine 9.27mg/dL), anemia (hemoglobin 7.6g/dL), thrombocytopenia (platelets 113k/μL), and renal biopsy confirming malignant arteriolar nephrosclerosis and thrombotic microangiopathy. Previously prescribed 20-mg azilsartan daily, he lost consciousness the next day and was urgently admitted with a blood pressure of 118mmHg and increased serum creatinine from 1.28 to 9.27mg/dL over 6months. Azilsartan was stopped; blood pressure managed with 12.5mg of losartan daily, targeting systolic pressure between 150 and 160mmHg. His creatinine peaked on day 14; however, treatment with 12.5 - 50mg/day of losartan and 5 - 10mg/day of amlodipine gradually improved renal function to 4.48mg/dL by month ten without hemodialysis or further syncope. Our case suggests a gradual approach to blood-pressure management to avoid ischemic risks.