PA27.1-7 | Renal Pathology I: Glomerular Disease & Renal Failure — Practice Quiz

Which component of the glomerular filtration barrier is primarily responsible for preventing albumin from passing into the filtrate through its charge-selective electrostatic repulsion?

A 6-year-old boy presents with periorbital oedema noticed each morning. Urine shows 3+ protein, no RBCs, no casts. Serum albumin 1.8 g/dL; complement C3 normal. Renal biopsy: no light-microscopic abnormality; electron microscopy shows diffuse effacement of podocyte foot processes. Which of the following best explains the pathogenesis?

A 35-year-old man with 10-year history of poorly controlled type 2 diabetes is found to have proteinuria 4.2 g/day, serum albumin 2.4 g/dL, and bilateral pitting oedema. Renal biopsy shows nodular glomerulosclerosis with peripheral capillary loop accentuation. Which histological finding is pathognomonic of his diagnosis?

A 48-year-old woman develops haematuria and RBC casts 2 weeks after a streptococcal throat infection. Serum C3 is markedly reduced; C4 is normal. Renal biopsy shows diffuse endocapillary proliferation on LM; electron microscopy reveals subepithelial 'hump-shaped' electron-dense deposits. What is the immunofluorescence pattern expected?

A 32-year-old woman with SLE develops nephrotic-range proteinuria, haematuria, and RBC casts. Serum anti-dsDNA titre is very high; C3 and C4 are both low. Renal biopsy IF shows IgG, IgA, IgM, C3, C4, and C1q deposits in a 'full-house' pattern. LM reveals wire-loop lesions. Which WHO/ISN class of lupus nephritis is most likely?

A 55-year-old man with a 20-year history of hypertension presents with slowly progressive renal impairment. Urinalysis shows mild proteinuria (0.8 g/day) with no haematuria. Renal biopsy shows hyaline arteriolosclerosis, fibrous intimal thickening of interlobular arteries, globally sclerosed glomeruli, and tubular atrophy. What is the most likely diagnosis?

A 28-year-old man with HIV presents with nephrotic-range proteinuria (7 g/day), serum albumin 2.0 g/dL, and rapidly progressive renal failure. Renal biopsy shows segmental sclerosis and collapse of glomerular tufts with podocyte hypertrophy and prominent tubular microcysts. Electron microscopy shows tubuloreticular inclusions. What is this lesion?

A 45-year-old man presents with haemoptysis and rapidly progressive renal failure. Urinalysis shows RBC casts. Serum anti-GBM antibody titre is markedly elevated; ANCA is negative. Chest X-ray shows bilateral pulmonary infiltrates. Renal biopsy reveals >70% glomeruli with crescents and linear IgG on immunofluorescence. Which of the following is the correct classification of this RPGN?

A clinical vignette: A 19-year-old man presents with intermittent cola-coloured urine, typically appearing 1–2 days after upper respiratory tract infections ('synpharyngitic haematuria'). Between episodes his urinalysis is normal; proteinuria is mild (<1 g/day). Serum IgA is elevated; C3 is normal. Renal biopsy shows mesangial hypercellularity. What is the expected immunofluorescence finding?

A 22-year-old female presents with haematuria and nephrotic-range proteinuria. Renal biopsy shows membranous nephropathy; immunofluorescence reveals granular IgG4 and C3 in a subepithelial pattern; electron microscopy shows subepithelial deposits with intervening GBM projections ('spike-and-dome'). Serology for which autoantibody should be sent to confirm primary (idiopathic) membranous nephropathy?

A clinical vignette: A 65-year-old woman with chronic heart failure on furosemide is admitted for acute decompensation. She is oliguric; urine output drops to 200 mL/day. Urine sodium is 8 mEq/L, urine creatinine is 320 mg/dL, serum creatinine is 2.2 mg/dL (was 1.0 mg/dL one week ago). Urine osmolality is 620 mOsm/kg. Urinalysis: no casts. Which type of AKI does she have and what is the approximate FENa?

A clinical vignette: A 58-year-old man with sepsis is admitted to ICU. He was normotensive on day 1, then had an episode of profound hypotension requiring vasopressors. By day 3, he develops oliguric AKI; urinalysis reveals granular 'muddy-brown' casts and renal tubular epithelial cell casts; FENa is 3.8%. Which phase of acute tubular necrosis (ATN) is he most likely in, and what is its mechanism?

A 72-year-old man with a 30-year history of type 2 diabetes and hypertension has eGFR of 22 mL/min/1.73 m² (CKD Stage G4). He complains of bone pain and muscle weakness. Investigations: serum calcium 7.6 mg/dL (↓), phosphate 6.8 mg/dL (↑), PTH 890 pg/mL (↑↑), alkaline phosphatase elevated, X-rays show subperiosteal bone resorption. Which pathophysiological sequence best explains his skeletal disease?

A clinical vignette: A 68-year-old man with CKD Stage G5 (eGFR 8 mL/min/1.73 m²) secondary to diabetes presents with confusion, vomiting, and pericardial friction rub. ECG shows diffuse saddle-shaped ST elevation. His serum urea is 178 mg/dL and creatinine 9.4 mg/dL. He reports severe pruritus and a whitish deposit visible around his lips. Which of the following syndromes explains this clinical picture?