Pathoma-Renal Flashcards Preview

USMLE Step 1 > Pathoma-Renal > Flashcards

Flashcards in Pathoma-Renal Deck (37)
Loading flashcards...

Horseshoe Kidney

Kidney develops in pelvis then ascends to abdomen ** Gets caught on IMA


Renal agenesis (Potter sequence)

Absence of kidney formation ** Unilateral or bilateral ** Unilateral - kidney lacking one kidney, so existing kidney undergoes hypertrophy; becomes problem down the line with hyperifltration injury ** Bilateral - oligohydramnios. Consequence of this is lung hypoplasia (baby in womb is breathing in and out amniotic fluid... stretching and collapsing allows for development of lung to occur); flat face w/ low set ears; developmental defects of extremities


Dysplastic Kidney

noninherited, congenital malformation of renal parenchyma characterized by cysts and abnormal tissue (e.g. cartilage) ** Must be distinguished from inherited PCKD



Inherited defect ** Bilateral enlargement of kidneys ** Cysts in renal cortex and medulla


Autosomal recessive PCKD

Classically juvenile form ** Presents with renal failure and HTN ** Newborns can present with Potter sequence ** Associated with congenital hepatic fibrosis and hepatic cysts (think ab this when have baby with portal hypertension)


Autosomal dominant PCKD

- young ADults ** - defect in Adult Polycystic Kidney Disease 1 or 2 ** - HTN, hematuria, or worsening renal failure ** - Increased plasma renin ** - Associated w/ berry aneurysm, hepatic cysts and mitral valve prolapse ** - Cysts in brain (cystic dilatations from berry aneurysms), cysts in liver and cysts in kidney


Medullary Cystic Kidney Disease

Inherited defect ** Cysts in kidney ** But cysts in medullary collecting ducts ** Shrunken kidneys ** PCKD - have large kidneys ** In this dz, kidneys are shrunken and kids present with worsening renal failure


Acute Renal Failure

Hallmark is azotemia (increase in BUN and creatinine) and often with oliguria ** Pre renal, post renal, intra renal


Pre renal azotemia

Decrease blood flow ** Results in: ** decreased GFR, azotemia, oliguria ** Both BUN and creatinine rise, but if BUN:Cr > 15 can help w diagnosis ** - Creatinine does not have ability like BUN to be resorbed ** - With low BF, RAAS activated and adlosterone causes absorption of sodium, leading to absorption of water, leading to absorption of BUN out of tubule, leading to B:C > 15 ** - Tubular function remains intact so FENa remains < 1% ** - Urine osm > 500 indicating kidney able to fxn and resorb sodium


Post renal azotemia

Output obstruction causing back pressure ** Backpressure decreases GFR because can't filter as much ** Early stages: Increased tubular pressure forces BUN into blood increasing BUN:Cr > 15 ** Tubular function remains intact in early stage so FENa < 1% and urine osmolality >500 ** Long standing: Decreased reabsorption of BUN so BUN:Cr < 15 because tubule epithelial damaged ** Ability to reabsorb sodium is damaged so FENa > 2% and urine osmolality is <500


Intrarenal azotemia

Problems within kidney ** 1. Acute tubular necrosis



Injury and necrosis of tubular epithelial cells; most common cause of ARF ** Necrotic cells plug tubules; obstruction decreases GFR ** Brown, tubular casts seen in urine ** Intrarenal azotemia created


Ischemic ATN

Proximal tubule and thick ascending limb are particularly susceptible b/c require most energy


Nephrotoxic ATN

Proximal tubule is most susceptible ** Causes: ** Aminoglycosides ** Heavy metals (lead) ** Myoglobinuria (crush injury) ** Ethylene glycol (antifreeze) - can also see crystals in urine ** Radiocontrast dye ** Urate - can happen with tumor lysis syndrome; hydrate patients and use allopurinol to prevent accumulation of uric acid


Clinical features of ATN

Oliguria with brown, granular casts ** Elevated BUN and creatinine ** Hyperkalemia with metabolic acidosis - due to decreased renal excretion of potassium ** associated with increased anion gap


Acute interstitial nephritis

Hypersensitivity reaction ** Renal papillae necrosis ** Causes: ** chronic analgesic abuse ** DM ** Sickle cell traite ** Severe acute pyelonephritis



Only protein loss is albumin ** Excellent response to steroids (b/c damage is mediated by cytokines from T cells... can be caused by Hodgkin b/c of R-S cells)


Focal Segmental Glomerular Sclerosis

Most common in hispanics and AA ** Associated with HIV, heroin use, and sickle cell disease ** If patient with minimal change disease given steroids and progress instead of get better, progresses to FSGS ** negative IF also (not driven by immune complex deposition)


Membranous nephropathy

Most common nephrotic syndrome in Caucasian adults ** May be associated w/ hep B or C, solid tumors, SLE, or drugs ** If lupus patients have nephrotic syndrome, they have membranous nephropathy ** Key finding - thick glomerular basement membrane on H and E ** Thickening of membrane due to immune complex deposition ** Deposition at level of podocyte - sub epithelial ** Detected by IF ** Podocyte will try to lay down extra BM and get spike and dome appearance on EM


Membranoproliferative Glomerulonephritis

- thick capillary on H and E (due to immune complex deposition... graunlar IF) ** - mesangial cell holding capillary loops will have increased cytoplasm, separating deposit and creating tram track deposit ** - Immune complex can be under endothelium or in basement membrane ** Mesangial cell proliferates cytoplasm and cuts through middle of deposit, separating deposit into tram track appearance


Types of MPGN

Type I - subendothelial (under endothelial); associated with HBV and HCV; more often associated with formation of tram tracks ** Type II - deposition of immunocomplexes in basement membrane; associated with C3 nephritic factor (stabilizes C3 converstase leading to overactivation of complement causing inflammation and causing this disorder)



- C3 --> C3a + C3b via C3convertase ** - Type II MPGN has immunglobulin that stabilizes C3 convertase so it's not broken down as fast ** This leads to overactivation of complement so get decrease serum C3


Membranotype diseases

Always have immune complex deposits ** In 1 of 3 locations ** - Membranous glomerulonephropathy: subepithelium ** - TI MPGN: Sub endothelium ** - TII MPGN: In basement membrane ** Get granular on IF


Six types nephrotic syndrome

- MCD ** - FSGN ** - MEMG ** - MPGN (two types) ** - DM ** -


Diabetes Mellitus Nephropathy

Preferentially get NEG of efferent arteriole - so need ACEi


Systemic amyloidosis

Kidney most commonly involved organ ** Apple-green birefringence under polarized light


Nephritic biopsy

Hypercellular, inflamed gomeruli ** Immune-complex deposition activates complement ** C5a attracts neutrophils causing hypercellularity


Post Strep Glomerulonephritis

Nephritic syndrome after Group A Beta hemolytic ** Carries M protein virulence factor (this is what defines nephritogenic strains) ** Presents 2-3 weeks after infection ** Hematuria (cola-colored) ** Oliguria ** Periorbital edema ** Biopsy: hypercellular, inflamed glomeruli ** Subepithleial humps on EM ** Deposit eventually dissipates and pass through epithelium and resolve ** Tx is supportive ** Fears: Rapidly progressive Glomerulonephritis



Nephritic syndrome that progresses to renal failure within weeks to months ** Characterized by crescents in Bowman space ** Crescent made up of fibrin and macrophages



Antibody against glomerular and alveolar basement membranes ** linear IF ** Can present with hematuria and hemoptysis ** Classically in young, adult male



PSGN ** Diffuse proliferative glomerulonephritis - get deposition of Antibody antigen complex, usually sub-endothelial ** High yield: most common disease in lupus patients


Negative IF

Pauce immune ** Perform ANCA test


ANCA test

Take patient's serum and introduce to ANCA slide ** If bind adjacent to nucleus - p-ANCA ** If bind out in cytoplasm - c-ANCA



Wegener granulomatosis ** Get RPGN ** Involves nasopharynx, hematuria, and RPGN with crescents ** If patient also has sinusitis then think about wegeners ** would have no IF as opposed to goodpastures linear IF



Microscopic polyangiitis or ** Churg strauss - have granulomatous inflammation, eosinophilia, and asthma


IgA nephropathy

Deposits in mesangium ** Nothing else gives IgA on IF ** Presents during childhood ** Microscopic hematuria with RBC casts ** Usual follows episodic mucosal infections ** May slowly progress to renal failure


Alport syndrome

Inherited defect in type IV collagen ** Most commonly X-linked ** Isolated hematuria, hearing loss and ocular disturbances

Decks in USMLE Step 1 Class (97):