# Kidney I for NEET PG Pathology: AKI, CKD, Nephritic and Nephrotic Syndrome, Glomerulonephritis, IgA, RPGN, Lupus and Diabetic Nephropathy Source: https://tracknation.in/story/kidney-i-for-neet-pg-pathology-aki-ckd-nephritic-and-nephrotic-syndrome-glomerulonephritis-iga-rpgn-lupus-and-diabetic-nephropathy (TrackNation — free UPSC notes with PYQs) > NEET PG Pathology: acute kidney injury criteria and urinary indices, chronic kidney disease, nephritic vs nephrotic syndrome, minimal change disease, FSGS, membranous nephropathy, MPGN, diabetic nephropathy, post-infectious GN, IgA nephropathy, RPGN and anti-GBM disease, lupus nephritis and Alport syndrome, with a diagram, hooks, vignette MCQs and cards. ## Start Here 🎯 **Exam priority: High.** *Expect: nephritic vs nephrotic, the biopsy hallmark of each glomerular disease (foot processes, spikes, humps, linear IgG, crescents, Kimmelstiel-Wilson), IgA vs post-infectious timing, lupus classes, AKI criteria and prerenal vs tubular indices, and the casts of CKD.* CBME mapping: **PA 27.2–27.7**. Tubules, infection, cysts, stones and tumours are in article 22; amyloid kidney in article 6; urine examination in article 16. *Nephritic vs nephrotic syndrome, glomerular diseases, AKI and CKD. Drawn by TrackNation.* ## Acute and Chronic Kidney Injury - **AKI**: a fall in kidney function over days to weeks with azotaemia. KDIGO definition — creatinine up ≥ 0.3 mg/dL within 48 hours, or ≥ 1.5 times baseline within 7 days, or urine < 0.5 mL/kg/h for 6 hours. Causes are prerenal (poor perfusion), renal (intrinsic) or postrenal (obstruction). Prerenal AKI and acute tubular injury are the commonest in hospital. - Tubular injury gives tubular cells and many **brown granular casts**; urinary eosinophils hint at allergic interstitial nephritis. - **CKD**: eGFR < 60 mL/min/1.73 m² for ≥ 3 months is the most reliable evidence; small kidneys on ultrasound favour CKD. Commonest causes: diabetic nephropathy, then hypertensive nephrosclerosis. **Broad and waxy casts** mark advanced failure. - CKD complications: **normocytic normochromic anaemia** (too little erythropoietin); less calcitriol → low calcium, phosphate retention, secondary hyperparathyroidism and renal osteodystrophy. | **Index** | **Prerenal** | **Tubular injury** | | Urine sodium (mmol/L) | < 10 | > 40 | | Fractional excretion of sodium | < 1% | > 1% | | BUN/creatinine ratio | > 20 | < 10 | | Urine/plasma osmolality | > 1.5 | 1–1.5 | | Sediment | Bland | Tubular cells, many brown granular casts | ## Nephrotic Syndrome - **Definition**: protein > 3 g/day from a glomerular disorder, with oedema and hypoalbuminaemia. Lipiduria (oval fat bodies, fatty casts). Loss of antithrombin III → clots, especially **renal vein thrombosis**. - **Minimal change disease**: 70–90% of nephrotic syndrome in children over 1 year; diffuse **effacement of foot processes** on electron microscopy; steroid responsive. Rare secondary causes: NSAIDs, Hodgkin lymphoma. - **FSGS**: sclerosis begins in some (focal) glomeruli and in part of each tuft (segmental); commonest primary nephrotic syndrome in US adults. Secondary: heroin, HIV, obesity, sickle cell disease. HIV-associated nephropathy shows the **collapsing** variant. - **Membranous nephropathy**: an adult disease; target antigen **PLA2R** on podocytes. Subepithelial deposits with **spikes** of basement membrane between them. Secondary to drugs, infections, autoimmunity, cancer. - **MPGN**: thickened GBM with **double contours**; immune-complex or complement-mediated (C3 GN, dense deposit disease). - **Diabetic nephropathy**: commonest cause of nephrotic syndrome in adults and of kidney failure worldwide. Early hyperfiltration; thick GBM; nodular glomerulosclerosis = **Kimmelstiel-Wilson** lesions; hyalinosis of both afferent and efferent arterioles. ## Nephritic Syndrome and RPGN - **Definition**: haematuria with dysmorphic red cells and often **red cell casts**, variable proteinuria. - **Post-infectious GN**: commonest acute GN in children 3–15 years; nephritogenic group A streptococci (pharyngitis or impetigo strains) after a latency of 6–21 days. Cola-coloured urine, oedema, hypertension. Subepithelial **humps** on EM; low C3 that normalises within 6–8 weeks in 80%. - **IgA nephropathy**: commonest GN worldwide. Poorly glycosylated IgA1 binds mesangial cells. Gross haematuria **1–2 days** after a mucosal infection — a shorter latency than post-infectious GN. - **RPGN**: nephritic syndrome with glomerular **crescents** and kidney failure in weeks to months. By immunofluorescence: anti-GBM (~20%, **linear IgG**; Goodpasture when the lung bleeds too — antibody against type IV collagen), immune complex (~50%; post-infectious, IgA, lupus and others) and pauci-immune (~30%, ANCA vasculitis such as granulomatosis with polyangiitis). - **Lupus nephritis**: class I minimal, II mesangial, III focal (< 50% glomeruli), **IV diffuse (> 50%, commonest)**, V membranous (nephrotic), VI sclerosing. Wire loops are an activity lesion. - **Hereditary**: Alport syndrome (type IV collagen gene, mostly X-linked, with sensorineural deafness and eye changes); thin basement membrane disease (GBM 150–225 nm instead of 300–400 nm; isolated microscopic haematuria). ## Traps the Examiner Sets - Haematuria 1–2 days after a cold = IgA; 1–3 weeks after a sore throat or skin infection = post-infectious GN. - Linear IgG = anti-GBM; immune-complex deposits = immune-complex GN; few or none = pauci-immune (ANCA). - Spikes = membranous; humps = post-infectious; foot processes only = minimal change. - FENa < 1% = prerenal; > 1% = tubular injury. - Waxy and broad casts = advanced CKD; red cell casts = glomerulonephritis. ## Memory Hooks & Shortcuts *Shortcuts to lock in this article's numbers and lists. Each one only re-packages facts proven above.* - 🧠 **IgA comes In A day (1–2 days); strep takes three weeks** — IgA vs PIGN latency - 🧠 **Spikes for Membranous, Humps for Post-strep, Foot processes for Minimal change** — EM hallmarks - 🧠 **Linear = Lung + kidney (anti-GBM)** — Goodpasture - 🧠 **Kimmelstiel-Wilson = Kandy (diabetes) nodules** — diabetic nephropathy - 🧠 **Waxy = Way past it (advanced CKD)** — casts - 🧠 **Prerenal Preserves sodium (FENa < 1%)** — AKI indices ## Rapid-Revision Cards - Cr ↑ ≥ 0.3 mg/dL in 48 h, or ≥ 1.5× in 7 d, or urine < 0.5 mL/kg/h × 6 h. - Urine Na < 10, FENa < 1%, BUN/Cr > 20. - FENa > 1%; brown granular casts. - eGFR < 60 for ≥ 3 months; small kidneys. - Broad and waxy. - Normocytic; low erythropoietin. - Low calcitriol → hypocalcaemia. - > 3 g/day, oedema, low albumin, lipiduria. - Renal vein thrombosis; AT-III loss. - Children; foot-process effacement; steroids; Hodgkin. - Adults (US); heroin, HIV, obesity, sickle. - Collapsing FSGS. - Adults; PLA2R; subepithelial spikes. - Double-contour GBM. - Kimmelstiel-Wilson nodules; afferent + efferent hyalinosis. - Haematuria, dysmorphic RBCs, RBC casts. - 6–21 days after strep; humps; low C3. - Commonest GN; haematuria 1–2 days after URTI. - Crescents; anti-GBM 20%, IC 50%, pauci 30%. - Linear IgG; type IV collagen; lung + kidney. - Class IV diffuse commonest; V membranous. - Type IV collagen; X-linked; deafness. - 150–225 nm; benign haematuria. ## Sources *Facts in this article were checked against these documents.* - MSD Manual Professional: Acute Kidney Injury; Chronic Kidney Disease — Merck & Co. (MSD Manuals), reviewed 2026 (link) - MSD Manual Professional: Glomerular Disorders (nephritic and nephrotic overviews, PIGN, IgA nephropathy, RPGN, minimal change disease, FSGS, membranous nephropathy, MPGN, diabetic nephropathy, lupus nephritis, Alport syndrome, thin basement membrane disease, HIV-associated nephropathy) — Merck & Co. (MSD Manuals), reviewed 2025–26 (link) - MSD Manual Professional: Anti-Glomerular Basement Membrane Disease — Merck & Co. (MSD Manuals), reviewed 2025 (link) - Competency Based Undergraduate Curriculum, Pathology (PA 27) — National Medical Commission, 2024 ## Test Yourself: Practice Questions Thirty-two questions in NEET PG style, most of them clinical vignettes. ## Practice Questions (NEET PG pattern) *Original questions written in the style of the exam: +4 for a correct answer, −1 for a wrong one. Every answer was checked against the sources listed above. NEET PG papers are not published by NBEMS, so these are not past-paper questions.* **Q1.** A hospital patient's creatinine rises from 1.0 to 1.4 mg/dL within 48 hours. By KDIGO criteria this is - (a) normal variation - (b) chronic kidney disease - (c) nephrotic syndrome - (d) acute kidney injury **Answer: (d)** — A rise of ≥ 0.3 mg/dL in 48 hours meets the definition. **Q2.** An oliguric patient after severe diarrhoea has urine sodium 8 mmol/L, FENa 0.5% and BUN/creatinine ratio 25. The AKI is most likely - (a) acute tubular injury - (b) postrenal obstruction - (c) prerenal - (d) acute interstitial nephritis **Answer: (c)** — Tubular injury: urine Na > 40, FENa > 1%, ratio < 10. **Q3.** Urine sediment shows tubular epithelial cells and many brown granular casts in an oliguric patient after prolonged hypotension. This points to - (a) IgA nephropathy - (b) prerenal azotaemia - (c) minimal change disease - (d) acute tubular injury **Answer: (d)** — Prerenal sediment is usually bland. **Q4.** The most reliable evidence that kidney disease is chronic rather than acute is - (a) eGFR below 60 for at least 3 months - (b) oliguria - (c) a single high creatinine - (d) red cell casts **Answer: (a)** — Small kidneys on ultrasound also favour CKD. **Q5.** Urine from a patient with advanced renal failure shows broad, highly refractile casts. They are - (a) white cell casts - (b) waxy casts - (c) red cell casts - (d) hyaline casts only **Answer: (b)** — Broad or waxy casts are prominent in advanced failure of any cause. **Q6.** A patient with stage 4 CKD has haematocrit 25%, normal MCV and normal MCHC. The main cause is - (a) iron deficiency always - (b) haemolysis - (c) deficient erythropoietin production - (d) B12 deficiency **Answer: (c)** — Anaemia of CKD is normochromic normocytic. **Q7.** Hypocalcaemia in CKD is mainly due to - (a) excess vitamin D - (b) reduced renal production of calcitriol - (c) low phosphate - (d) excess PTH **Answer: (b)** — Phosphate retention adds to it. **Q8.** The two commonest causes of CKD, in order, are - (a) lupus, then IgA - (b) polycystic kidney, then stones - (c) TB, then amyloid - (d) diabetic nephropathy, then hypertensive nephrosclerosis **Answer: (d)** — Then glomerulopathies. **Q9.** A 4-year-old has oedema, urine protein over 3 g/day, a non-nephritic sediment and normal kidney function. Electron microscopy shows diffuse effacement of podocyte foot processes. The diagnosis is - (a) post-infectious GN - (b) membranous nephropathy - (c) Alport syndrome - (d) minimal change disease **Answer: (d)** — 70–90% of nephrotic syndrome in children over 1 year; steroid responsive. **Q10.** A patient with Hodgkin lymphoma develops nephrotic syndrome. The glomerular lesion classically associated is - (a) anti-GBM disease - (b) membranous nephropathy - (c) IgA nephropathy - (d) minimal change disease **Answer: (d)** — NSAIDs are the other secondary cause. **Q11.** Nephrotic syndrome is defined by proteinuria above - (a) 1 g/day - (b) 30 mg/g creatinine - (c) 150 mg/day - (d) 3 g/day with oedema and hypoalbuminaemia **Answer: (d)** — From a glomerular disorder. **Q12.** The thrombotic complication especially typical of nephrotic syndrome is - (a) renal vein thrombosis - (b) papillary necrosis - (c) pyelonephritis - (d) renal stone **Answer: (a)** — Antithrombin III is lost in the urine. **Q13.** Urine microscopy in nephrotic syndrome shows tubular cells packed with lipid. These are - (a) clue cells - (b) red cell casts - (c) waxy casts - (d) oval fat bodies **Answer: (d)** — Lipiduria also gives fatty casts. **Q14.** Biopsy from an adult with nephrotic syndrome shows subepithelial deposits with spikes of basement membrane between them; serum anti-PLA2R antibody is positive. The diagnosis is - (a) FSGS - (b) membranous nephropathy - (c) MPGN - (d) minimal change disease **Answer: (b)** — PLA2R on podocytes is the major target antigen. **Q15.** A patient with HIV infection and heavy proteinuria has a biopsy showing collapsing glomerulopathy. This is a variant of - (a) IgA nephropathy - (b) focal segmental glomerulosclerosis - (c) membranous nephropathy - (d) MPGN **Answer: (b)** — HIV-associated nephropathy. **Q16.** Secondary FSGS is associated with all of the following EXCEPT - (a) IgA vasculitis as the main cause - (b) obesity - (c) sickle cell disease - (d) heroin use **Answer: (a)** — Also HIV and nephron loss. **Q17.** A silver stain of a glomerulus shows a thickened basement membrane with a double contour ('tram track'). The pattern is - (a) diabetic nephropathy - (b) thin basement membrane disease - (c) minimal change disease - (d) membranoproliferative glomerulonephritis **Answer: (d)** — Immune-complex or complement (C3) mediated. **Q18.** Kidney biopsy from a long-standing diabetic shows rounded nodules of mesangial matrix and hyalinosis of both afferent and efferent arterioles. The nodules are - (a) crescents - (b) wire loops - (c) humps - (d) Kimmelstiel-Wilson lesions **Answer: (d)** — Nodular intercapillary glomerulosclerosis. **Q19.** The commonest cause of kidney failure worldwide is - (a) polycystic kidney disease - (b) IgA nephropathy - (c) diabetic nephropathy - (d) lupus nephritis **Answer: (c)** — Also the commonest cause of nephrotic syndrome in adults. **Q20.** Two weeks after a streptococcal sore throat, a 7-year-old passes cola-coloured urine and has oedema and hypertension. Which finding is expected? - (a) normal complement with IgA deposits - (b) linear IgG on immunofluorescence - (c) positive anti-PLA2R - (d) low serum C3 **Answer: (d)** — C3 returns to normal within 6–8 weeks in 80%. **Q21.** Electron microscopy in post-streptococcal glomerulonephritis typically shows - (a) spikes - (b) foot-process effacement only - (c) linear deposits - (d) hump-shaped subepithelial immune complex deposits **Answer: (d)** — With endocapillary proliferation. **Q22.** A man has recurrent gross haematuria; the latest episode began one day after an upper respiratory infection. The likely diagnosis is - (a) post-streptococcal GN - (b) minimal change disease - (c) membranous nephropathy - (d) IgA nephropathy **Answer: (d)** — Post-infectious GN has a latency of 1–3 weeks. **Q23.** The commonest form of glomerulonephritis worldwide is - (a) post-streptococcal GN - (b) IgA nephropathy - (c) anti-GBM disease - (d) lupus nephritis **Answer: (b)** — Commoner in Asia. **Q24.** Rapidly progressive glomerulonephritis is defined histologically by - (a) foot-process effacement - (b) Kimmelstiel-Wilson nodules - (c) thin basement membrane - (d) glomerular crescents **Answer: (d)** — Kidney failure follows within weeks to months. **Q25.** A smoker has haemoptysis and rapidly rising creatinine. Immunofluorescence of the kidney shows linear IgG along the GBM. The antibody targets - (a) neutrophil proteinase 3 - (b) PLA2R - (c) double-stranded DNA - (d) type IV collagen of basement membranes **Answer: (d)** — Anti-GBM (Goodpasture) disease. **Q26.** RPGN with crescents but few or no immune deposits on immunofluorescence is usually due to - (a) post-streptococcal GN - (b) ANCA-associated vasculitis - (c) anti-GBM antibody - (d) lupus **Answer: (b)** — Pauci-immune, about 30% of RPGN. **Q27.** The commonest class of lupus nephritis, with proliferation in more than half the glomeruli, is - (a) class VI (sclerosing) - (b) class I (minimal mesangial) - (c) class IV (diffuse) - (d) class II (mesangial) **Answer: (c)** — Class V is membranous and usually nephrotic. **Q28.** A boy has haematuria, progressive kidney disease and high-frequency sensorineural hearing loss; his maternal uncle had kidney failure. The defective protein is - (a) fibrillin - (b) nephrin only - (c) type IV collagen - (d) polycystin **Answer: (c)** — Alport syndrome, most often X-linked. **Q29.** A healthy adult has isolated microscopic haematuria and normal kidney function; electron microscopy shows a GBM about 200 nm wide. The diagnosis is - (a) Alport syndrome - (b) IgA nephropathy - (c) minimal change disease - (d) thin basement membrane disease **Answer: (d)** — Normal GBM is 300–400 nm. **Q30.** Nephritic syndrome is characterised by - (a) proteinuria > 3 g/day with lipiduria - (b) glycosuria - (c) haematuria with dysmorphic red cells and red cell casts - (d) pyuria with white cell casts **Answer: (c)** — Proteinuria is variable. **Q31.** Membranous nephropathy is best described as - (a) a crescentic GN - (b) mainly an adult disease, often secondary to drugs, infections, autoimmunity or cancer - (c) the commonest nephrotic syndrome of young children - (d) a hereditary collagen disease **Answer: (b)** — Most cases are primary (PLA2R). **Q32.** The commonest cause of primary nephrotic syndrome in adults (US data) is - (a) post-infectious GN - (b) focal segmental glomerulosclerosis - (c) IgA nephropathy - (d) minimal change disease **Answer: (b)** — Especially common in Black men. ### Active Recall From memory: define AKI by KDIGO and separate prerenal from tubular injury; define CKD and list its casts, anaemia and mineral changes; contrast nephritic and nephrotic syndrome; give the biopsy hallmark of minimal change, FSGS, membranous, MPGN and diabetic nephropathy; contrast IgA and post-infectious GN; classify RPGN by immunofluorescence; and name the commonest lupus class and the Alport defect.