Chapter 20- The Kidney Flashcards
What are the functions of the kidney?
Filters blood and produces urine
Waste excretion
Regulation of water concentration, salt, calcium, phosphorus, etc
Maintains plasma pH
Hormone production
What are the four compartments of the kidney?
- Glomeruli
- Tubules
- Interstitium
- Vessels
Chronic renal disease destroys what kidney compartments?
All of them
What is azotemia and what does it reflect?
Increased BUN/serum creatinine
Reflects reduced GFR
What is uremia?
Constellation of clinical signs and symptoms associated with azotemia
What type of collagen makes up the glomerulus BM?
Type IV
What cells support the glomerulus?
Mesangial cells
What type of cells are mesangial cells?
Contractile, phagocytic, secretive
What is glomerular filtration determined by?
Molecule size and charge
What type of iron is most permeable to the glomerulus?
Cations
What are the functions of the JGA?
BP and GFR
What structures are involved in the JGA?
DCT and afferent arteriole
What is the macula densa?
Specialized cells in the DCT
What is the function of the macula densa?
Detects sodium concentration (high levels contract the arteriole)
When is renin secreted?
When BP falls
What are the pathologic responses to glomerular injury?
- Hypercellularity
- GBM thickening
- Hylainosis
- Sclerosis
What form of hypercellularity is seen in acute glomerular injury?
Crescents
What mechanisms underlie most forms of glomerular injury?
Immune- deposition of complexes, Abs against Ags or GBM
What is the pathogenesis of Goodpasture syndrome?
Ab against Type IV collagen
Where do cations, anions and neutral molecules accumulate in the glomerulus?
Cations- cross BM, form subepithelial complexes
Anions- trapped subendothelially
Neutral- accumulate in mesangium
What is a common feature of glomerular disease and why?
Epithelial cell injury
Podocytes have limited regenerative capacity
What are the major features of progressive renal disease?
- Focal segmental glomeeulosclerosis
2. Tubulointerstitial fibrosis
What is nephritic syndrome?
Manifestation of glomerular inflammation
What is nephritic syndrome characterized by?
Hematuria
Oliguria
Azotemia
Proteinuria
Hypertension
What are the forms of nephritic syndrome and what are they caused by?
- Acute proliferative glomerulonephritis- post Strep infections
- Non-Strep acute glomerulonephritis- other infections
- Rapidly progressive/crescentic glomerulonephritis- idiopathic or systemic
What is nephrotic syndrome?
Derangement in capillary walls causes increased plasma protein permeability
Loss of albumin in nephrotic syndrome causes what?
Systemic edema
What diseases cause nephrotic syndrome?
Membranous nephropathy (adults)
Minimum change disease (children)
Focal segmental glomerulosclerosis
Idiopathic focal segmental glomerulosclerosis
HIV associated neohropathy
Membranoproliferative glomerulonephritis
What is the difference between membranous nephropathy and minimum change disease (besides age)?
MN- immune mediated
MCD- not immune mediated
What is the most common cause of adult nephrotic syndrome?
Focal segmental glomerulosclerosis
What is HIV associated nephropathy a variant of?
Focal segmental glomerulosclerosis
What is the most common type of glomerulonephritis worldwide?
IgA nephropathy (Berger disease)
What is the pathology of IgA nephropathy?
IgA deposits cause gross hematuria following infection
What is the cause of hereditary nephritis?
X-linked mutation
Defective type IV collagen
What is another name for hereditary nephritis?
Alport syndrome
What are the symptoms of hereditary nephritis?
Chronic renal failure
Nerve deafness
Eye disorders
What kind of mutation causes thin BM lesions?
Type IV collagen mutation
What is the morphology of chronic glomerulonephritis?
Kidneys are bilaterally/symmetrically contracted with granular surface and thinned cortex
Completely effaced glomeruli (can’t ID primary lesion)
What are the symptoms of chronic glomerulonephritis?
Hypertension Pericarditis Gastroenteritis Secondary hyperparathyroidism Renal osteosystrophy
What are examples of glomerular lesions associated with systemic diseases?
- Henoch-Schonlein purpura
Lupus nephritis
GN associated with bacterial endocarditis and other infections
Diabetic nephropathy
Fibrillary glomerulonephritis
Goodpasture syndrome
Microscopic polyangitis
Wegner granulomatosis
Essential mixed cryoglobulinemia
Plasma cell dyscrasias
What are the characteristics of Henoch-Schonlein purpura?
IgA deposition in children, vasculitis, abdominal symptoms, joint pain, glomerulonephritis
What are the major processes of tubular and intertitial disease?
- Ischemic/toxic tubular injury (acute tubular injury)
2. Inflammatory reactions of tubules and interstitium
What is the most common cause if ARF?
Ischemic/toxic tubular injury
What does ischemia and direct toxic injury to kidney tubules lead to?
Necrosis
What are the phases of ischemic/toxic tubular injury?
- Initiation
- Maintenance
- Recovery
What can cause luminal destruction in tubular injury?
Injured cells detach from BM and cause obstruction
What is tubulointerstitial nephritis?
Absence of nephritic and nephrotic syndromes
What are examples of inflammatory reactions of tubules and interstitium?
Tubulointerstitial nephritis
Pyelonephritis and UTI
What type of infections cause most UTIs?
Gram negative GI normal flora
What route of spread is most common in pyelonephritis and UTI?
Ascending route
What is the morphology of acute pyelonephritis?
Patchy suppurative inflammation
Tubular necrosis
Neutrophil cast
Renal scars from necrosis, pyonephrosis, perinephric abscesses
What is the morphology of chronic pyelonephritis?
Tubulointerstitial inflammation
Irregular renal scarring
Dilated/deformed calyxes
What are the types of chronic pyelonephritis and which is most common?
Reflux nephropathy- most common
Chronic obstructive pyelonephritis
What is the second most common cause of acute tubular injury?
Tubulointerstitial nephritis induced by drugs and toxins
What kind of response does acute, drug-induced interstitial nephritis cause?
IgE and T cell response
What is the morphology of acute urate nephropathy?
Uric avid crystals ppt in tubules and CDs
What causes chronic urate nephropathy?
Prolonged hyperuricemia (gout)
What is nephrolithiasis?
Uric acid stones
What is hypercalcemia and nephrocalcinosis?
Renal calcium deposition and stone formation
What is the other name for light chain cast nephropathy?
Myeloma kidney
What condition is light chain cast nephropathy associated with?
Multiple myeloma
What occurs in bile cast nephropathy?
Increased serum bilirubin causes bile cast formation
What is hepatorenal syndrome?
Impairment of renal function in patients with liver failure
What is nephrosclerosis?
Renal arteriolar sclerosis
Wall thickening and hyalinization
What is the morphology of nephrosclerosis?
Vascular lesions cause diffuse, ischemic nephron atrophy
Cortex shrinking
Granular surface
Small kidneys
What is malignant nephrosclerosis?
Nephrosclerosis superimposed on hypertensive chronic renal disease or scleroderma
What is the morphology of malignant nephrosclerosis?
Fibrinoid necrosis
Intravascular thrombosis
Salt and water retention
What is the pathology of malignant nephrosclerosis?
Stimulation of RAS- aldosterone causes salt and water retention
Drives an ever-increasing cycle of BP
What does renal artery stenosis induce?
Excessive renin secretion
What is most renal artery sclerosis due to?
Atheromatous plaque
What is the morphology of renal artery sclerosis?
Reduced kidney size
Diffuse ischemic atrophy
What are thrombotic microangiopathies?
Spectrum of syndromes that cause excessive platelet activation
Thromboses in kidney vessels cause hypertension
What are the two forms of thrombotic microangiopathies and there causes?
- Thrombotic thrombocytopenia purpura (TTP)- ADAMSTS13 deficiencies (vWF regulator)
- Hemolytic uremic syndrome (HUS)- shiga-toxin producing bacteria (typical) or mutations in complement regulatory proteins (atypical)
What other vascular disorders are associated with kidney disease?
Atheroembolic renal disease (cholesterol crystals embolize)
Sickle cell nephropathy
Diffuse cortical nephrosis (diffuse microthrombi)
Renal infarcts
Why do renal infarcts occur?
Little collateral circulation
What congenital anomalies are associated with the kidneys?
Agenesis
Hypoplasia (unilateral)
Ectopic
Horseshoe kidneys
What is the difference between bilateral and unilateral agenesis?
Bilateral- incompatible with life
Unilateral- hypertrophy of remaining kidney
Is hypoplasia normally unilateral or bilateral?
Unilateral
What are the characteristics of true kidney hypoplasia?
No scars, less than 6 renal lobes
Where do ectopic kidneys normally lie?
Just above the pelvic brim or in the pelvis
Why is their an increased risk of bacterial infection in ectopic kidneys?
Ureter can be tortuous or kinked
What is the difference between simple and crossed ectopic kidneys?
Simple- kidneys are in an abnormal position on the proper side
Crossed- both kidneys are on the same side
What type of pole fusion is most common in horseshoe kidneys?
Lower pole
What types of cystic diseases can occur in kidneys?
Autosomal dominant polycystic kidney disease
Autosomal recessive PKD
Medullary sponge kidney
Nephronophthisis and adult onset medullary cystic disease
Multicystic renal dysplasia
Acquired (dialysis associated) cystic disease
Simple cysts
Which form of PKD is adult and which is childhood?
Adult- autosomal dominant PKD
Childhood- autosomal recessive PKD
What are the characteristics of AD PKD?
High penetrance, universally bilateral
PKD1 mutation in most cases
Kidneys are massively enlarged and almost entirely cystic
40% also show liver cysts
What are the characteristics of AR PKD?
Mutations in PKHD1
Liver almost always has cysts and proliferating bile ducts
Sponge-like appearance due to small cysts in the cortex
Bilateral
What is the morphology of medullary sponge kidney?
Multiple cystic dilations of the collecting ducts in the medulla
Pyramids are lost and filled with cysts
What is the morphology of nephronophthisis and adult onset medullary cystic disease?
Variable number of cysts in the medulla, concentrated at the corticomedullary junction
Small, contracted kidneys
Granular surface
What is the morphology of multicystic renal dysplasia?
Unilateral or bilateral
Kidney is large, irregular and multicystic
What are most cases of multicystic renal dysplasia associated with?
Ureteropelvic obstruction
Urethral agenesis
Atresia
Why do prolonged dialysis patients develop cysts?
Obstruction from calculi and interstitial fibrosis
Where do simple cysts of the kidney commonly occur?
Cortex
What is the morphology of simple kidney cysts?
Smooth walls filled with clear, serous fluid
What are the characteristics of urinary tract obstruction?
Increased susceptibility to infection and stone formation
Renal atrophy and expanded renal pelvis
What is hydronephrosis?
Dilation of renal pelvis and calicoes due to urine obstruction outflow
What is urolithiasis?
Increased concentrations of stone constituents
Where is urolithiasis most common in the kidney?
Calyces and pelvis
What benign neoplasms are associated with the kidney and what are their characteristics?
- Renal papillary adenomatous- small, yellow, cortical
- Angiomyolipoma- hamartomatous lesion (vessels, muscle, fat)
- Oncocytoma- eosinophilic epithelial cells, packed with mitochondria
What malignant neoplasm is histologically identical to low grade papillary RCC?
Renal papillary adenoma
What is the cut off between benign and malignant renal papillary adenoma?
3cm
Why are angiomyolipomas significant?
Can cause hemorrhage
What malignant neoplasms are associated with the kidney?
Renal cell carcinoma (RCC)
Clear cell carcinoma
Papillary carcinomas
Chromophobe renal carcinoma
Urothelial carcinoma of the renal pelvis
What is the most common form of renal cancer in adults?
RCC
What are the three forms of RCC and their characteristics?
- Clear cell- solitary, spherical masses, invade the renal vein
- Papillary- multifocal and bilateral, hemorrhagic and cystic, papillary formations (microscopic)
- Chromophobe- eosinophilic cells with perinuclear halos
What is paraneoplastic syndrome attributable to?
Hormone production
Why do urothelial carcinomas of the renal pelvis manifest early?
Produce hematuria or obstruction
What concomitant tumour can occur with urothelial carcinomas of the renal pelvis?
Bladder