Robbin's 20: The Kidney Flashcards
Give the expected BUN:creatinine ratio for azotemia due to dilated cardiomyopathy.
>20:1 Azotemia - high SG, low FE-Na, high BUN:creatinine ratio, pre-renal when associated with HF
Give the expected BUN:creatinine ratio for BPH
BPH - post-renal (obstructive) 10:1 - 20:1
What would you expect to see on urinalysis of a patient with SLE and nephritic syndrome?
RBC casts, RBCs
Give an example of a type I hypersensitivity rxn in the kidney:
Allergic nephritis; drug-induced acute interstitial nephritis
Give an example of a type IV hypersensitivity rxn in the kidney.
Renal transplant rejection; SOME cases of drug-induced acute interstitial nephritis Transplant rejection - T-cell injury with tubulitis
Give an example of a type III hypersensitivity rxn in the kidney.
SLE: immune-mediated glomerular injury with antigen-antibody complex deposition –> decreased levels of complement –> nephritis
Give an example of a type II hypersensitivity rxn in the kidney.
Goodpasture syndrome, other anti-glomerular BM diseases
Juxtaglomerular cells secrete:
renin
Parietal epithelial cells line the Bowman capsule and may proliferate with severe glomerular injury to produce:
crescents
Podocytes are visceral epithelial cells that form what part of the kidney?
The filtration barrier
Thrombotic microangiopathies are most likely to be damaged with:
endothelial cells
What kind of cell proliferates in membranoproliferative glomerulonephritis?
Mesangial cells phagocytic fx and can proliferate in response to injury
What defines nephrotic syndrome?
Podocyte injury, the loss of >3.5g protein per day in the urine
What is the exotoxin responsible for the development of poststreptococcal glomerulonephritis?
Pyogenic exotoxin B (SpeB) Most children with poststreptococcal GN recover, although 1% develop a rapidly progressive GN characterized by crescent formation. Progression to chronic renal failure occurs in 40% of affected adults.
What is a more common cause of PSGN in the US than Strep pyogenes?
Staph Aureus (with IgA antibodies)
Patients with Goodpasture syndrome (type I anti-glomerular BM disease) require what kind of treatment?
Plasmapheresis
Give an example of a type II crescentic GN.
Immune complex disease: Type II crescentic GN can occur in systemic lupus erythematosus, in Henoch-Schönlein purpura, and after infections.
What are some causes of type III crescentic GN?
Type III - absense of anti-GBM antibodies or immune complexes Causes of type III crescentic GN include granulomatosis with polyangiits (ANCA-associated vasculitis) and microscopic polyangiitis.
Give the dx: Malaise, nausea and reduced urine output for 3 days; Afebrile, normotensive; creatinine 7.5; Hematurea, no pyuria or glucosuria; renal biopsy shows crescents
Rapidly progressive GN Crescentic GN is divided into three groups on the basis of immunofluorescence: type I (anti–glomerular basement membrane [GBM] disease); type II (immune complex disease); and type III (characterized by the absence of anti-GBM antibodies or immune complexes).
Antibodies are seen against what part of the BM in Goodpasture syndrome?
The noncollagenous domain of the alpha-3 chain of type IV collagen
The anti-streptolysin O titer is increased in what kidney disease?
poststreptococcal GN –granular pattern of immune complex deposition
Immune complex deposition of granular or linear in Goodpasture syndrome?
Linear
HIV infection can lead to a nephropathy that resembles FSGS, with what deposition?
IgM and C3 are deposited in the mesangial areas of affected glomeruli
Give the dx: LACK of immune deposits; periorbital edema; BUN:creatinine >10:1; Oliguria with cloudy brown appearance; focal necrosis in glomeruli with glomerular BM breaks and no crescents; Anti-neutrophil cytoplasmic antibody detected in serum
Pauci-immune crescentic glomerulonephritis Cases can be idiopathic, associated with ANCAs, and limited to the kidney.
Anti-DNA topoisomerase antibody is seen in:
scleroderma (mainly affects vasculature of kidney)
Give the dx: Serum positive for C-ANCA; Biopsy shows glomerular crescents and damage to small arteries; BUN:Creatinine about 10:1; ABSENCE of immune complexes of anti-GBM antibodies
GPA - granulomatosis with polyangiitis A Necrotizing granulomatous vasculitis Granulomatosis with polyangiitis (ANCA-associated vasculitis) is a cause for rapidly progressive glomerulonephritis (GN) characterized by epithelial crescents in Bowman space.
Does FSGS affect renal vessels?
No, but GPA does
Give the dx: Focal hemorrhages and necrosis in kidney WITHOUT a granulomatous component; BP usually high
hyperplastic arteriosclerosis
Membranous nephropathy is most likely to produce nephrotic syndrome (>3.5 proteinuria) with or without crescents?
Without
Give the dx: Diffuse BM thickening; Granular deposits of IgG and C3 common; Antibody targeting M-type phospholipase A2 receptor antigen; Proteinuria
Membranous nephropathy causing nephrotic syndrome
Give the dx: Children, facial puffiness; Kidney looks normal on light microscopy but foot processes fused on EM;
Minimal change disease
What is the cause of minimal change disease?
The most likely cause of foot process fusion is a primary injury to visceral epithelial cells caused by T cell–derived cytokines.
Immune complex deposition in adults is/is not steroid responsive?
Is not
Certain verocytotoxin-producing Escherichia coli strains can cause hemolytic uremic syndrome by:
Injury to the capillary endothelium
Effacement of the foot processes seen in minimal change disease results in:
Selective proteinuria or low molecular weight proteins, for example, albumin
Subepithelial electron-dense humps represent immune complexes seen in:
Postinfectious GN
Give the dx: Malaise and periorbital edema; Afebrile; Proteinuria but no hematuria or gluccosuria; Numerous oval fat bodies seen on u/a; elevated serum creatinine; no improvement on steroid therapy; 50% affected glomeruli
FSGS Manifests with nephrotic syndrome; May be linked with NPHS gene mutations
Minimal change disease is aka:
lipoid nephrosis; no glomerular changes seen by light microscopy
DM causes what kidney changes?
Nodular hyaline mesangial deposits - diabetic nephropathy A diabetic patient with nephrotic syndrome is likely to have nodular (and diffuse) glomerulosclerosis or diffuse thickening of the basement membrane.
Rapidly progressive GN is principally associated with:
Hematuria, crescents
An acute proliferative postinfectious GN would show what on light microscopy?
Hypercellular glomeruli with neutrophils **NO BM thickening
Corticosteroid-resistant hematuria and proteinuria leading to hypertension and renal failure is typical for:
FSGS - dysfunction of podocyte slit-diaphragm apparatus - corticosteroid resistant Mutations in genes affecting several proteins, including nephrin and podocin, have been found in inherited cases of FSGS; podocyte dysfunction, possibly caused by cytokines or unknown toxic factors, may be responsible for acquired cases of FSGS.
C3NeF is an autoantibody directed against C3 convertase, and it is seen in:
Membranoproliferative GN
Give the dx: Deafness; Corneal erosions (lens dislocation possible); Hematuria; Inherited defects in BM collagen
Alport syndrome Proteinuria may be in the nephrotic range; Chronic renal failure in adulthood
Give the dx: GN; Prominent ribbon-like deposits along the lamina densa of the glomerular BM; Hematuria, proteinuria
Dense deposit disease Half of all cases end in chronic renal failure
IgA nephropathy (mesagial IgA staining byimmunofluroescence) occurs with increased frequency in patients with:
Celiac disease, liver disease
Development of recurrent hematuria after a viral illness in a child or young adult is typically associated with
IgA nephropathy A renal biopsy specimen will show diffuse mesangial proliferation and electron-dense deposits in the mesangium. In these patients, some defect in immune regulation causes excessive mucosal IgA synthesis in response to viral or other environmental antigens. IgA complexes are deposited in the mesangium and initiate glomerular injury.
The foamy change in the tubular epithelial cells and ultrastructural alterations of the basement membrane are characteristic features of:
Alport syndrome The genetic defect results from mutation in the gene for the α5 chain of type IV collagen.
Symmetrically smaller kidneys are seen in:
Chronic GN; often no inciting cause; surfaces of kidneys become granular; HTN develops due to renal ischemia
IV drug users that devlop endocarditis can have kidneys that display what pathology?
Wedge-shaped regions of yellow-white cortical necrosis –emboli infarcting the cortex of the kidneys septic emboli can produce abscesses where they lodge in the vasculature
Why do patients with acute tubular injury excrete large volumes of urine?
the glomerular filtrate cannot be adequately reabsorbed by the damaged tubular epithelium
Renal calculi is a complication of:
gout
What drugs cause interstitial nephritis?
sulfonamides, penicillins, cephalosporins, the fluoroquinolone antibiotics ciprofloxacin and norfloxacin, and the antituberculous drugs isoniazid and rifampin. Acute tubulointerstitial nephritis also can occur with use of thiazide and loop diuretics, cimetidine, ranitidine, omeprazole, and nonsteroidal anti-inflammatory drugs. The disease manifests about 2 weeks after the patient begins to use the drug.
Bence-Jones proteinuria is characteristic of:
Multiple myeloma Amyloid deposition enlarges these kidneys
Myoglobinuria most often results from:
rhabdomyolysis, such as after severe crush injuries
Besides gout, in what diagnoses is hyperuricemia seen?
Leukemias and lymphomas that have a high proliferative rate and are treated with chemotherapy
What kind of E. Coli causes HUS?
verocytoxin-producing, O157:H7 This Shiga toxin damages endothelium, reducing nitric oxide, promoting vasoconstriction and necrosis, and promoting platelet activation to form thrombi in small vessels.
Name two common extrarenal findings in adults with ADPKD.
Berry aneurysm; Liver cysts
Give the dx: Patients usually develop kidney stones, infection, or recurrent hematuria in the third or fourth decade; often bilateral; cystic dilation of 1 to 5 mm is present in the inner medullary and papillary collecting ducts.
Medullary sponge kidney
Give the dx: rare congenital disease and leads to bilateral, symmetric renal enlargement manifested in utero, with renal failure evident at birth.
Autosomal recessive polycystic kidney disease (ARPKD)
Give the dx: bilaterally small kidneys with barely visible medullary cysts concentrated at the corticomedullary junction; mutation in NPHP1;
Nephronophthisis; most common genetic cause of end-stage renal disease in children and adolescents; AR
Recurrent urinary tract infections with urea-splitting organisms such as Proteus can lead to formation of:
Magnesium ammonium phosphate stones known as “staghorn calculi”
Most sporadic clear cell carcinomas show loss of both alleles of the ___ gene.
VHL
The second most common carcinoma of the kidney in adults is papillary renal cell carcinoma, associated with what gene mutations?
MET can be familial or sporadic
