Renal Path Flashcards
Horseshoe Kidney
Conjoined kidney.
Connected at lower pole.
Kidney in lower abdomen bc gets caught on inferior mesenteric artery root during ascent from pelvis to abdomen.
Renal Agenesis
Absent kidney formation.
Unilateral –> hypertrophy of existing kidney; hyper filtration increases risk of renal failure.
Bilateral –> oligohydramnios w lung hypoplasia, flat face, low set ears, developmental defects of extremities (aka Potter sequence); incompatible w life.
Dysplastic Kidney
Noninherited.
Congenital malformation of renal parenchyma.
Cysts and abnormal tissue (i.e. cartilage).
Usu unilateral.
Bilateral - distinguish from inherited polycystic kidney disease.
Polycystic Kidney Disease (PKD)
Inherited.
Bilateral enlarged kidney w cysts in renal cortex and medulla.
Autosomal recessive: infants w worsening renal failure and HTN, may have Potter sequence; assoc w congenital hepatic fibrosis (leads to portal HTN) and hepatic cysts.
Autosomal dominant: young adults w HTN (due to ^ renin), hematuria, worsening renal failure; mutation in APKD1 or APDK2 gene; cysts develop over time; assoc w berry aneurism, hepatic cysts, mitral valve prolapse.
Medullary Cystic Kidney Disease
Inherited, autosomal dominant.
Cysts in medullary collecting ducts.
Parenchymal fibrosis –> shrunken kidneys and worsening renal failure.
Acute Renal Failure (general)
Acute, severe decrease in renal fcn. Develops within days. Azotemia - increased BUN (blood urea nitrogen) and creatinine. Often oliguria (low urine production). Prerenal, postrenal, and intrarenal.
Prerenal Azotemia
Caused by decreased blood flow to kidneys –> v GFR, azotemia, and oliguria.
Reabsorption of fluid and BUN (serum BUN:Cr >15)
Tubular fcn intact and can still resorb Na and concentrate urine (fractional excretion sodium (FENa) < 1%; urine osmolality > 500 mOsm/kg)
Postrenal Azotemia
Due to obstruction of urinary tract downstream from the kidneys.
Decreased outflow –> v GFR, azotemia, oliguria.
Early stage - ^ tubular pressure forces BUN into blood (BUN:Cr >15); tubular fcn intact (FENa<1% and urine osmolality >500).
Long-standing obstruction –> tubular damage –> decreased reabsorption of BUN (<15), decreased reabsorption of Na (FENa>2%), inability to concentrate urine (<500).
Acute Tubular Necrosis (intrarenal azotemia)
Injury and necrosis of tubular epithelial cells –> ARF.
Necrotic cells plug tubules –> v GFR.
Brown granular casts.
Decreased reabsorption BUN (BUN:Cr <15)
Decreased reabsorption Na (FENa >2%)
Inability to concentrate urine (<500)
Ischemic etiology - due to decreased blood supply; often preceded by pre renal azotmeia; proximal tubule and thick ascending limb most susceptible.
Nephrotic etiology - due to toxic agents, most commonly aminoglycosides; proximal tubule; hydration and allopurinol used prior to starting chemo to decrease risk of urate-induced.
Hyperkalemia (decreased renal excretion) w metabolic acidosis.
Reversible, but may need supportive dialysis.
Oliguria can persist 2-3 weeks.
Acute Interstitial Nephritis (intrarenal azotemia)
Drug-induced HSR. Interstitium and tubules involved. NSAIDs, penicillin, and diuretics. Oliguria, fever, rash after starting new drug. Eosinophils in urine. Resolves w drug cessation. May progress to renal papillary failure.
Renal Papillary Necrosis
Necrosis of renal papillae.
Gross hematuria and flank pain.
Causes: chronic analgesic abuse, diabetes mellitus, sickle cell trait/disease, severe acute pyelonephritis.
NephrOtic Syndrome
Glomerular disorder w prOteinuria (>3.5g/day) –>
-hypoalbuminemia (pitting edema)
-hypogammaglobinemia (^ risk of infection)
-hypercoaguable state (bc loss of antithrombin III)
-hyperlipidemia and hypercholesterolemia (fatty casts in urine)
Syndromes include: MCD, FSGS, membranous nephropathy, membranoproliferative glomerulonephritis, diabetes mellitus, systemic amyloidosis.
Minimal Change Disease (MCD)
Most common nephrotic syndrome in kids. Idiopathic. Assoc w Hodgkin lymphoma. Normal glomeruli on H&E. Effacement of foot processes on EM. Negative immunofluorescence - no immune complex deposits. Selective proteinuria - loss of albumin, not immunoglobulin. Treat w steroids.
Focal Segmental Glomerulonephritis (FSGN)
Most common nephrotic syndrome in Hispanics and African Americans.
Idiopathic.
Assoc w HIV, heroin use, sickle cell disease.
Focal (some glomeruli) segmental (only part of glomerulus) sclerosis on H&E.
Effacement of foot processes on EM.
Negative IF.
Poor response to steroids.
–> chronic renal failure.
Membranous Nephropathy
Most common nephrotic syndrome in Caucasian adults.
Idiopathic.
Assoc w hep B or C, solid tumors, SLE, or drugs.
Thick glomerular basement membrane on H&E.
Due to immune complex deposition - granular IF.
Subepithelial deposits w “spike and dome” on EM.
Poor response to steroids.
–> chronic renal failure.
Membranoproliferative Glomerulonephritis
Thick glomerular basement membrane on H&E.
Due to immune complex deposition - granular IF.
Type I: subendothelial deposits; assoc w HBV and HCV; “tram track” appearance.
Type II: dense deposit disease - intramembranous deposits; assoc w C3 nephritic factor (autoAb that stabilizes C3 convertase –> over activation of complement, inflammation, low levels of circulating C3).
Poor response to steroids.
–> chronic renal failure.
Diabetes Mellitus
High serum glucose –> nonenzymatic glycosylation of vascular basement membrane - makes membrane leaky and protein enters –> hyaline arteriosclerosis.
Glomerular efferent arteriole more affected –> high glomerular filtration pressure.
Hyperfiltration injury –> microalbuminuria.
Progresses –> nephrotic syndrome.
Sclerosis of mesangium and Kimmelstiel Wilson nodules.
ACE inhibitors slow progression.
Systemic Amyloidosis
Kidney most commonly involved.
Amyloid deposits in the mesangium –> nephrotic syndrome.
Apple-green birefringence under polarized light after Congo red stain.
Nephr-I-tic Syndrome
Glomerular disorder w I-nflammation and bleeding.
Limited proteinuria (<3.5 g/day).
Oliguria and azotemia.
Salt retention w periorbital edema and HTN.
RBC casts and dysmorphic RBCs.
Hypercellular, inflamed glomeruli.
Immune complex deposition activates complement - C5a attracts neutrophils –> damage.
Includes PGSN, rapidly progressive glomerulonephritis, IgA nephropathy, alport syndrome.
Poststreptococcal Glomerulonephritis (PSGN)
Nephritic syndrome that arises after group A beta-hemolytic strep infection of the skin or pharynx.
Nephritogenic strains carry M protein virulence factor.
2-3 weeks after the infection - hematuria (cola colored urine), oliguria, HTN, periorbital edema.
Usu in kids.
Hypercellular, inflamed glomeruli on H&E.
Immune complex deposition - granular IF.
Subepithelial “humps” on EM.
Supportive treatment.
Some adults –> RPGN.
Rapidly Progressive Glomerulonephritis (RPGN)
Nephritic syndrome –> renal failure in weeks-months.
Crescents in Bowman’s space on H&E - crescents composed of fibrin and macrophages.
Linear IF (ant-basement membrane Ab) - Goodpasture syndrome - Ab against collagen in glomerular and alveolar basement membrane - hematuria and hemoptysis - young, adult males.
Granular IF (immune complex deposition) - PSGN or diffuse proliferative glomerulonephritis - diffuse antigen antibody complex deposition, usu sub-endothelial - assoc w SLE.
Negative IF (pauci-immune) - Wegener granulomatosis (c-ANCA), microscopic polyangiitis (p-ANCA), or Churg-Strauss syndrome (granulomatous inflammation, eosinophilia, asthma)
IgA Nephropathy (Berger Disease)
Most common nephrotic syndrome.
IgA immune complex deposition in mesangium - seen on IF.
Children present w episodic gross or microscopic hematuria w RBC casts - usu after a mucosal infection (^IgA).
May slowly –> renal failure.
Alport Syndrome
Nephrotic syndrome.
Inherited defect in type IV collagen - usu X-linked.
–> thinning and splitting of glomerular basement membrane.
Isolated hematuria, sensory hearing loss, ocular disturbances.
UTIs (general)
Infection of urethra, bladder, or kidneys.
Usu. ascending infection.
Females.
Risk factors: sexual intercourse, urinary stasis, catheters.
