Renal Tubular Diseases and Congenital Diseases Flashcards Preview

Renal > Renal Tubular Diseases and Congenital Diseases > Flashcards

Flashcards in Renal Tubular Diseases and Congenital Diseases Deck (47)
Loading flashcards...
1
Q

definition of acute tubular necrosis (ATN)

A

destruction of tubular epithelial cells with suppression of kidney functions leading to acute renal failure (ARF)

the latter becomes clinically apparent when tubular insufficiency is reduced by 80%

a common cause of ARF

2
Q

types of ATN

A

ischemic and toxic

3
Q

ischemic ATN

A

usually pre-renal, characterized by pale kidneys, edema, pathcy necrosis of proximal tubule, rupture of TBMs

casts in the distal tubules and collecting ducts

4
Q

nephrotoxic ATN

A

antibiotics- or othe rtoxins-induced

characterized by diffuse necrosis of middle segment of the proximal tubule

histologic changes depend on the type of the agent

recovery phase is characterized by regenerating epithelium

5
Q

What is the primary event in ischemic injury?

A

marked reduction/cessation of aerobic respiration, impairment of oxidative phsophorylation by mitochondria and loss of ATP

activation of proteases, phospholipases and generation of O2 radicals that cause cell death

6
Q

What happens in reversible early injury of the tubules in ATN?

A

the cell polarity and redistribution of Na-K ATPase leads to increased concentration of sodium in the tubular lumen and constriction of afferent arteriole of the glomerulus

note that the proximal tubular cells are very much dependent upon aerobic respiration, while the distal tubular cells are capable of anaerobic glycolysis and thus can maintain cellular integrity and functions for a longer hypoxic period

7
Q

What happens in irreversible injury in ATN?

A

there is a loss of mitochondrial functions and cell membrane integrity that leads to cell death (necrosis or apoptosis)

8
Q

direct hemodynamic effects of ischemia

A

activation of RAS

increased endothelin expression

decreased NO and PGI2 production

9
Q

nephrotoxic injury ATN

A

critical event is the formation of free radicals that injure the cell membranes by lipid peroxidation and followed by cell death

these events are similar to reversible injury that is seen in irreversible injury due to ischemia

10
Q

phases of acute tubular necrosis

A

oliguric phase

early diuretic phase

late diuretic phase

11
Q

oliguric phase of ATN

A

characterized by loss of tubular functions, uremia, hyperkalemia, metabolic acidosis, and fluid overload

12
Q

early diuretic phase of ATN

A

characterized by progressive increase of urine output, howevve,r tubular functions remain impaired

as a result, there are massive losses of fluid and electrolytes, and hypokalemia rather thna hyperkalemia is observed

13
Q

late diuretic phase of ATN

A

characterized by progressive increase in the concentrating ability of tubules line with regenerating epithelia, and uremia subsides

renal functions return to level over a period of a couple months

14
Q

tubulointerstitial nephritis (TIN)

A

primary structural and functional alterations of tubules and interstitium

may be acute with interstitial edema, PMN infiltration, and focal tubular necrosis

may also be chronis with interstitial fibrosis and tubular atrophy

15
Q

causes of TIN in man

A

bacterial infection (pyelonephritis)

toxins

metabolic disorders

urinary stones and strictures

neoplasms

immunologic assault

vascular anomalies

polycystic disease

16
Q

general characteristics of acute pyelonephritis

A

characterized by acute suppurative bacterial infection of kidney and renal pelvis

second most common infectious disease in man

usually caused by organisms that include predominantly (85%) gram-negative bacilli, and serological studies point that the organisms are derived from patient’s own fecal flora

there are 2 major routes of infections to the kidneys

17
Q

What are the two major routes of infection to the kidneys for acute pyelonephritis?

A

hematogenous and ascending

18
Q

hematogenous route of infection for acute pyelonephritis

A

uncommon and caused by circulating Staphylococci or E. coli

normal kidney is highly resistant to blood-born infection, and obstruction dramatically enhances its susceptibility to UTIs

infected kidneys have multiple abcesses on its surface

19
Q

ascending route of infection for acute pyelonephritis

A

quite common

bacteria is commonly E. coli

ascends from the urethra and bladder

urinary tract obstruction greatly increases the risk of infection

with obstruction, bacteria multiple and colonization occurs

vesicoureteral reflux is the most important

20
Q

vesicoureteral reflux

A

major cause of urinary infections in children, and is due to the anomaly of the vesical segment of the ureter

infection is recurrent

condition is diagnosed by voiding cystourethrogram

surgically correctable

21
Q

pathology of acute pyelonephritis

A

characterized by patchy acute suppurative inflammation of interstitium and tubules with pus casts, tubular necrosis, and secondary involvement of glomeruli and blood vessels

the complications include perinephric abcesses, papillary necrosis (particularly in diabetics and urinary tract infections) and pyonephrosis

22
Q

characteristics of chronic pyelonephritis

A

characterized by chronic or recurrent infections of the kidney, renal pelvis, and calyces

usually bacterial in origin

usually associated with obstruction or vesicoureteral reflux, and resulting deformities of the pelvcalyceal systems distinguish it from other causes of tubulointerstitial diseases

23
Q

What are the types of chronic pyelonephritis?

A

chronic obstructive and reflux type

24
Q

chronic obstructive pyelonephritis

A

characterized by recurrent bouts of renal inflammation

usually associated with congenital anomalies

ex. posterior uretheral valve or vessel compressing on the ureter

may be unilateral or bilateral

25
Q

reflux type chronic pyelonephritis

A

common in young people

abnormal insertion of ureter into the urinary bladder

recurrent bouts of infection ultimately leading ot chronic polar damage to the kidney

26
Q

pathology of chronic pyelonephritis

A

deep surface scars on the kidney along with dilatation and distortion of the pelvicalyceal system

blunting of the papillae

microscopicaly, interstitial chornic inflammation, scarring, tubular atrophy with thyroidization of tubules containing casts are seen

glomeruli are relatively spared, except when focal segmental glomerulosclerosis sets in

27
Q

What are four factors that may be responsible for the susceptibility of the kidney to drug or toxins?

A

1) large blood supply
2) concentration of toxins in tubular fluid
3) secretion of certain toins by nephrons
4) concentration of toxins in medulla by the countercurrent mechanisms

28
Q

types of TIN

A

drug-induced TIN

acute hypersensitivity TIN

analgesic abuse TIN

NSAID-induced TIN

29
Q

analgesic abuse TIN

A

chronif corm of TIN due to excessive intake of analgesic mixtures (aspirin, phenacetin, caffeine)

papillary/medullary necrosis due to covalent binding, oxidative damage, and decreased prostaglandin synthesis locally

imparied urine concentrating ability and renal tubular acidosis

30
Q

histological findings of analgesic nephropathy

A

necorsis of medullary papilla

31
Q

general characteristics of drug-induced tubulo-interstitial nephritis (DITIN)

A

antiboitics, diuretics, NSAIDs

fever, rash, proteinuria, increased creatiinine

type-I hypersensitivity, IgE-mediated reaction

eosinophils - body tissue, blood, and urine

32
Q

histological findings of DITIN

A

interstitial edema and influx of eosinophils

focus of tubulitis (invasion of tubules)

33
Q

types of congenital anomalies of the kidney

A

agenesis - bilateral incompatible, unilateral-associated with adaptive changes

hypoplasia - developmental/acquired, unilateral-associated with adaptive changes

ectopic kidney - abnormal location, susceptible to infection

horseshoe kidney - 1:500 autopsies, 90% lower pole fusion

34
Q

thrombotic microangiopathies

A

conditions where the renal vasculature is involved secondarily due to systemic thrombosis

two condition with overlapping features include hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenia purpura (TTP)

pathology - thrombi in the capillaries due to denuddation of endothelium and activation of platelets

35
Q

cystic kidney disease

A

ADPKD

ARPKD

medullary sponge kidney

medullary cystic disease complex (recessive/dominant)

simple cysts (mostly incidental finding)

acquired renal cystic disease (hemodialysis)

36
Q

What are the clinico-pathologic characteristics of the autosomal recessive form of polycystic kidney disease (APRKD)?

A

large cystic kidneys at birth

radial fusiform cysts

hepatic fibrosis (fibrocystin)

bile duct proliferation

death in early childhood

splenomegaly

cysts appear as longitudinal cysts that are oriented at right angles to the cortical surface

37
Q

What are defining features of kidneys of patients with ARPKD?

A

fusiform cysts

large kidneys and hepatic fibrosis

bile duct proliferation

38
Q

What gene is responsible for ARPKD? What is its function?

A

fibrocystin

transmembrane protein responsible for cell-cell signaling

immunoglobulin type domain can interact with other proteins on other cells

39
Q

What are the clinico-pathologic characteristics of medullary sponge disease (MSD)?

A

bilateral medullary cysts - involves the collecting ducts

hematuria, infections

stones, gravel in urine

sometimes asymptomatic

benign course

40
Q

What are the clinico-pathologic characteristics of medullary cystic disease complex (MCDC)

A

cortico-medullary cysts

recessive (juvenile)

dominant (adult)

salt wasting, polyuria

nephronophthisis - wasting of the kidney

(nephrocystin) uremia leads to chronic renal failure

41
Q

What is the gene responsible for MCDC? What is its function?

A

nephrocystin

intracytoplasmic protein

important SH3 domain for binding to other adhesion proteins

42
Q

What are the clinico-pathologic characteristics of autosomal dominant polycystic kidney disease (ADPKD)?

A

tubular disease, high penetrance, occurs in any segment of the nephron and kidneys, become progressively larger

multiple genes (PKD1, PKD2, and PKD3)

familial, disvered in 2nd or 4th/5th decade of life

prevalence is 1:650

hematuria in teenage yars if received injury to flank regions

complications include rupture of cysts, pain and recurrent UTIs

liver or splenic cysts, colon diverticula, intracranial aneurysm

43
Q

pathogenesis of ADPKD

A

abnormal cell-matrix or cell-cell interactions

cellular proliferation and polarity characteristics of the cells with aberrant fluid secretion and accumulation (cAMP)

44
Q

What do the kidneys look like in ADPKD?

A

large kidneys with a lot of fluid

normal glomeruli

bilateral cysts

sometimes can see chocolate cysts - large cysts filled with blood clot

45
Q

What genes are affected in autosomal dominant polycystic kidney disease (ADPKD)?

A

85% PKD1 - chromosome 16

PKD2 - 15% of cases, chromosome 4

PKD3 - minority of cases

homotypic and heterotypic interactions between C-termini of polycystin-1 and -2 mutations lead to tubular dysmorphogenesis and disease

46
Q

Polycystin-1

A

transmembrane protein with extracellular N-terminus and multiple complex domains

extracellular lectin domain and Ig-like folds mediate cell-matrix interactions

complex that it forms lacks focal adhesion kinase (FAK) when mutant

47
Q

Polycystin-2

A

Na+ channel transmembrane protein with coiled-coil domain and SH3 domains in the intracellular side that interacts with polycystin-1