Clinical presentations of renal disease

Question 1

Mechanism of oliguria in pre-renal acute kidney injury

Answer 1

Decreased RBF and GFR –> increase proximal tubule reabsorption of Na and H2O –> increased aldosterone and ADH secretion –> increased distal tubule Na and H2O reabsorption

Question 2

Mechanism of oliguria in intrarenal acute kidney injury

Answer 2

Renal tubular injury –> cast formation –> obstruction and increased pressure –> tubular backleak –> decreased GFR

Question 3

Mechanism of post-renal oliguria in acute kidney injury

Answer 3

Bilateral obstruction to urine flow –> increased intraluminal pressure –> release of inflammatory mediators and cells injury –> renal vasoconstriction (causes renal tubular injury) –> edema and decreased GFR

Question 4

BUN/creatinine ratio in pre-renal acute kidney injury

Answer 4

> 20:1 –> increased

Question 5

Urinary sodium levels in pre-renal acute kidney injury

Answer 5

<20 –> normal

Question 6

Fractional excretion of sodium in pre-renal AKI

Answer 6

<1% –> normal

Question 7

Urine osmolality in pre-renal AKI

Answer 7

> 500 –> normal

Question 8

BUN/creatinine ratio in intra-renal AKI

Answer 8

10:1 –> low normal

Question 9

Urinary sodium levels in intra-renal AKI

Answer 9

> 40 –> high

Question 10

Urinary fractional excretion of sodium in intra-renal AKI

Answer 10

> 4% –> increased

Question 11

Urine osmolality in intra-renal AKI

Answer 11

<350 –> low

Question 12

BUN/creatinine ratio in post-renal AKI

Answer 12

> 10:1 –> normal

Question 13

Urinary sodium levels in post-renal AKI

Answer 13

> 40 –> high

Question 14

Fractional excretion of sodium in post-renal AKI

Answer 14

> 4% –> high

Question 15

Urine osmolality in post-renal AKI

Answer 15

<350 –> low

Question 16

Where are urinary casts formed?

Answer 16

Distal convoluted tubule or collecting duct

Question 17

Type of cast believed to com from damaged and dilated tubules, and therefore seen in end-stage chronic renal disease

Answer 17

Broad casts

Question 18

Polyuria with normal plasma glucose, low urine osmolality, and normal serum sodium. Normal urine osmolality after desmopressin.

Answer 18

Cranial diabetes insipidus

Question 19

Polyuria with normal plasma glucose, low urine osmolality, and normal serum sodium. Low urine osmolality after desmopressin.

Answer 19

Nephrogenic diabetes insipidus