Renal

Question 1

In horseshoe kidney, 2 kidneys are typically joined at [?] poles

Answer 1

Inferior poles

Question 2

During embryonic development, kidney develops in pelvis and ascends into upper abdomen.In patients w/ horseshoe kidney, where is kidney located? Why?

Answer 2

Horseshoe kidney abnormally located in lower abdomen b/c inferior mesenteric artery (IMA) impedes its ascent into upper abdomen.

Question 3

Horseshoe kidney a/w what condition?

Answer 3

Turner syndrome (45 XO)

Question 4

Unilateral renal agenesis:Existing kidney undergoes?Later-in-life complication?

Answer 4

Existing kidney –> Compensatory hypertrophyLater in life –> Hyperfiltration injury to existing kidney –> Predisposes to renal failure

Question 5

Bilateral renal agenesis:Embryologic defect?Fetal complication?

Answer 5

Embryologic defect –> Malformation of ureteric budFetal complication –> Oligohydramnios (low amniotic fluid)

Question 6

Bilateral renal agenesis –> Potter sequence:Clinical presentation (x3)?

Answer 6

Potter sequence:Oligohydramnios –> Pulmonary hypoplasia, flat face w/ low set ears, and developmental defects of limbs/extremities

Question 7

Cause of death in Potter sequence?

Answer 7

Pulmonary hypoplasia

Question 8

Potter sequence: 3 causes?

Answer 8

Bilateral renal agenesisARPKDPosterior urethral valves

Question 9

Renal dysplasia:Inheritance pattern?Embryologic defect?Histologic hallmark on biopsy?

Answer 9

Renal dysplasia = Dysplastic kidney- Non-inherited disorder- Embryologic defect –> Abnormal interaction b/w ureteric bud and metanephric mesoderm(Ureteric bud penetrates into sacral intermediate mesoderm to induce formation of metanephric mesoderm. Reciprocal exchange of inductive signals b/w 2 structures drives their differentiation into structures that form mature kidney.)- Histologic hallmark –> Cysts with abnormal structures (cartilage, immature collecting ductules)

Question 10

Unilateral renal dysplasia - Clinical presentation analogous to?

Answer 10

Unilateral renal agenesis - Dysplastic kidney –> Cystic with abnormal structures (cartilage, immature collecting ductules) –> Nonfunctional organ- Normal kidney –> Compensatory hyperplasia

Question 11

DDx of bilateral renal cysts in young child?

Answer 11

ARPKD and b/l renal dysplasia

Question 12

Site of cysts in medullary cystic disease?

Answer 12

Collecting ducts of medulla

Question 13

Medullary cystic disease:Cysts in collecting ducts of medulla causes what 2 renal complications?

Answer 13

1) Tubulointerstitial fibrosis –> Shrunken kidney2) Progressive renal insufficiency –> Inability to concentrate urine

Question 14

Medullary cystic disease:Gross appearance of kidney?

Answer 14

Shrunken kidney 2/2 tubulointerstitial fibrosis Note - Medullary cysts are not grossly visualized

Question 15

Medullary cystic disease:2 ways to diagnose?

Answer 15

1) Shrunken kidneys on US2) Medullary cysts on intravenous pyelogram (IVP)

Question 16

Medullary cystic disease v. polycystic kidney disease:- Location of cysts?- Size of kidneys?

Answer 16

Medullary cystic disease –> Cysts in collecting ducts of medulla. Shrunken kidneys 2/2 tubulointerstitial fibrosis.Polycystic kidney disease –> Cysts in cortex and medulla. Enlarged kidneys 2/2 cysts grossly visualized on organ surface

Question 17

Polycystic kidney disease- Autosomal recessive?- Autosomal dominant?

Answer 17

AR –> ARPKD –> Juvenile polycystic kidney disease –> Seen in childrenAD –> ADPKD –> Seen in adults

Question 18

ARPKD a/w 1 mutation:Gene?Chromosome?Gene product?Gene product function?

Answer 18

PKHD1 gene on chromosome 6–> Encodes fibrocystinFibrocystin modulates polycystin2 expression and function(Polycystin2 important in renal tubular development)

Question 19

ADPKD a/w 2 mutations:Genes?Chromosomes?Gene products?

Answer 19

PKD1 gene on chromosome 16 –> Encodes polycystin1PKD2 gene on chromosome 4 –> Encodes polycystin2

Question 20

ARPKD:Clinical presentation (x4)?

Answer 20

1) Renal cysts –> Bilateral enlarged kidneys 2) Hepatic cysts3) Congenital hepatic fibrosis –> Portal HTN4) Systemic HTN

Question 21

ARPKD:2 types of HTN?Mechanisms?

Answer 21

1) Portal HTN 2/2 congenital hepatic fibrosis2) Systemic HTN 2/2 elevated renin levels

Question 22

ADPKD:Clinical presentation (x4)?MCC of death (x2)?

Answer 22

CLINICAL PRESENTATION:1) Renal cysts –> Bilateral enlarged kidneys 2) Hepatic cysts3) Mitral valve prolapse4) Berry aneurysm5) Systemic HTN 2/2 elevated renin levels MCC OF DEATH:1) Chronic renal failure2) Ruptured berry aneurysm 2/2 systemic HTN (2/2 elevated renin levels)

Question 23

ADPKD a/w what cardiac condition?

Answer 23

Mitral valve prolapse

Question 24

Renal cyst found in outer cortex filled w/ ultrafiltrate 2/2 tubular obstruction?

Answer 24

Simple renal cyst

Question 25

Features of complex renal cyst?

Answer 25

Cyst may be septated, slightly calcified, or may have solid component that is non-enhancing or enhancing on CT

Question 26

Complex renal cyst on CT –> Next step?

Answer 26

Fine needle aspiration (FNA) or surgical removal 2/2 risk of renal cell carcinoma

Question 27

Clinical picture - Inflammation of connective tissue b/w renal tubules with pyuria (eosinophils in urine)?

Answer 27

Acute interstitial nephritis

Question 28

AIN may progress to what renal pathology?

Answer 28

Renal papillary necrosis

Question 29

NSAID-associated renal injury:Early?Chronic NSAID use?

Answer 29

Early: AIN that may progress to renal papillary necrosisChronic: Chronic interstitial nephritis

Question 30

Muddy brown casts?

Answer 30

Acute tubular necrosis (ATN)Necrosis and sloughing of tubular cells forms cast

Question 31

Clinical presentation of ATN?

Answer 31

Increased BUN/Cr, hyperK (2/2 decreased K+ excretion), and anion-gap metabolic acidosis (2/2 decreased excretion of organic acids)

Question 32

ATN - 2 cell types involved? Why?

Answer 32

Tubular cells in:- Proximal tubule- Medullary segment of thick ascending limbBoth susceptible to ischemic injury b/c both located in outer medulla –> Medulla receives only 10% of renal blood flow

Question 33

Why is ATN reversible?

Answer 33

B/c tubular cells are stable cells that can regenerateTakes some time to re-enter cell cycle though

Question 34

ATN - 3 stages?

Answer 34

1) Initial stage - Ischemic/toxic “inciting” event2) Maintenance stage - Oliguria3) Recovery phase

Question 35

ATN - Recovery phase?

Answer 35

Re-epithelialization of tubulesGradual increase in urine output –> High-volume diuresis (polyuria) but b/c tubular function isn’t yet totally recovered still risk of electrolyte imbalances

Question 36

ATN- Risk of what major electrolyte imbalance in maintenance phase?- In recovery stage?

Answer 36

Maintenance –> Hypokalemia and anion-gap metabolic acidosisRecovery –> Hyperkalemia

Question 37

Treatment of ATN?

Answer 37

Supportive therapy until tubular cells regenerate. Dialysis may be necessary b/c of danger of electrolyte imbalances

Question 38

ATN 2/2 ischemia – > Histology?

Answer 38

Flattening of tubular epithelial cells, loss of proximal tubule brush border –> Subsequent necrosis and DETACHMENT OF CELLS FROM BASEMENT MEMBRANE

Question 39

MCC of ATN 2/2 nephrotoxicity?

Answer 39

AminoglycosidesOthers - Heavy metals, ethylene glycol, radiocontrast dye, myoglobinuria (crush injury), hyperuricemia (tumor lysis), bence jones proteins (multiple myeloma)

Question 40

Renal papillary necrosis:Macroscopic finding?Microscopic finding?

Answer 40

Macro - Yellow necrosis at tips of renal pyramidsMicro - Coagulative necrosis