Renal

Question 1

Renal US - why?

Answer 1

safe, no dye or radiation
initial testing, most commonly used

choice for obstructive disease

can use doppler to assess vascular flow (RAS, RVT)

Question 2

Renal CT scan

Answer 2

Gold standard for renal stones
complementary to US
high sensitivity for PKD, tumors, and Dx RVY

Question 3

renal diagnostic preferred in children?

Answer 3

Radionuclide Scan

similar to CT, less radiation

Question 4

Gold standard diagnostic for RVT (renal vein thrombosis)?

Answer 4

MRI

also to further evaluate renal masses

Question 5

Renal arteriography and venography preferred to ID what d/o?

Answer 5

polyartertitis nodosa 
(multiple aneurysms and irregular constrictions)

Question 6

Gold standard for glomerular diseases ?

Answer 6

renal biopsy

• nephrotic, nephritic syndrome
• unexplained AKI

Question 7

KDIGO - AKI classification

Answer 7

Increase in Serum creatinine >0.3mg/dL in 48hrs

Increase serum creatinine to >1.5x baseline w/in prior 7 days
or

urine volume < 0.5mL/kg/hr ofr 6 hrs

there are 3 stages

Question 8

Quantify

Nonoliguria, Oliguria, Anuria

Answer 8

Nonoliguria > 500mL
Oliguria <500mL
Anuria <100mL

in 24 hr period

Question 9

3 Ddx of AKI (or an abnl creatinine)

Answer 9

prerenal AKI 60-70%
intrinsic AKI 20-40% –> ATN most common
posternal AKI 5-10%

Question 10

Most common cause of intrinsic AKI ?

Answer 10

ATN (acute tubular necrosis)

Question 11

BUN/creatinine ratios

Answer 11

Prerenal Azotemia: > 20/1 ratio

Renal Azotemia: ~10-15/1

Postrenal Azotemia: variable ratio

Question 12

What’s urea?

Answer 12

substance formed in liver when body breaks down protein.

renal diseases cause inadequate excretion of urea, which causes BUN to rise

liver disease = decrease BUN

hydration status affects BUN, elevated when dry, and also due to digestion of blood - so GI bleed

Question 13

Fractional excretion of Na+

prerenal vs intrinsic AKI

Answer 13

Prerenal <1%

Intrinsic >3%

Question 14

What value could you use to differentiate b/w prerenal and intrinsic AKI?

Answer 14

Fractional excretion of Na+ **most sensitive

Question 15

Possible causes of prerenal AKI azotemia

Answer 15

lack of perfusion to kidneys from..

• vascular depletion- (vomiting, diarrhea, anemia, GI bleed, DKA, addision’s dz, pancreatitis)
• low CO- (cardiogenic shock, CHF)
• change in vascular resistance- (sepsis, anaphylaxis, anesthesia - profound vasodilation- renal artery stenosis), and medications…)

Question 16

2 most common causes of ATN?

Answer 16

• ischemia (usu preceded from a prerenal azotemia)
• toxins
• ->exotoxins like vancomycin, aminoglycosides, amphotericin B, antineoplastics, and contrast
• ->endotoxins like heme, uric acid, paraproteins, rhabdomyolosis

Question 17

possible causes of intrinsic interstitial nephritis?

Answer 17

10-15% cases of intrinsic renal failure
Characterized by edema and tubular damage from interstitial inflammation

Cell mediated immune reaction i.e. post strep glomerulonephritis

Drugs most common cause (PCN, sulfa, NSAIDs)

Can also be infectious (CMV, strep)

Question 18

Hallmark finding of intrinsic renal disease?

Answer 18

unable to concentrate urine
(Really dilute urine)

Urine:
Dark granular casts
Urine sodium (> 30 mEq/dL) high
ABG: metabolic acidosis
Serum:
FENa % (> 2-3%)
BUN/creatinine ratio (< 20:1)