Non-diabetic kidney disease in a patient with type 2 diabetes mellitus: a case report

We report a type 2 diabetes mellitus patient with clinical and laboratory features of nephrotic syndrome. Pathohistological findings of the biopsy revealed idiopathic membranous nephropathy. A 54-year-old male patient was admitted to the hospital with clinical and laboratory features of nephrotic syndrome (serum creatinine 1.87 mg/dl, creatinine clearance 57 ml/ min, daily proteinuria 16 g). Immunological analyses (ANA-Hep2(IgG), ANCA, anti-GBM At(IgG), anti-PLA2R(IgG) antibodies) and tumour markers were negative. Abdominal ultrasound examination showed both kidneys to be normal diameter with parenchyma thickness of 17–18 mm, emphasized pyramids on both sides, without stasis or calculosis. Subsequently, macroscopic hematuria appeared (value sCr 4.38 mg/dl). A CT urography was done - revealing left renal vein thrombosis, accompanied by hydroureteronephrosis stage I/II left and potential ureteritis or tumour in the proximal part of the left ureter. The ureteritis was treated with quinolones. After 7 days CT scan was repeated, and the findings were the same - the high suspicion of a tumour of the ureteropelvic junction and the proximal part of the ureter was confirmed. An exploratory retrograde ureterorenoscopy was performed. The procedure revealed no evidence of tumour. Daily proteinuria was still nephrotic range (13.45 g). Two months later, a control CT scan of the abdomen and pelvis was conducted, and a kidney biopsy was performed. The pathohistological findings showed membranous nephropathy. The patient received the first dose of Rituximab at 375mg/m2 (750 mg intravenously). This same dose was administered again after two weeks. Patients with type 2 diabetes mellitus, nephrotic syndrome and rapidly declining renal function present diagnostic challenges due to the potential presence of associated non diabetic renal disease. Kidney biopsy is essential for pathohistological diagnosis. Understanding the spectrum of non-diabetic renal diseases in patients with type 2 diabetes mellitus is essential to improve clinical outcomes.