Renal Failure

Question 1

What is normal BUN

Answer 1

7-20mg/dL

Question 2

What is normal creatinine in males and females

Answer 2

Males: 0.8 to 1.4 mg/dL
Females: 0.6-1.2 mg/dL

Question 3

What is normal BUN:Cr ratio

Answer 3

10:1 up to 20:1

Question 4

What is acute kidney injury?

Answer 4

Rapid decline in renal function with an increase in serum creatinine by 50% or 05 to 1.0 mg/dL

Question 5

What are the 3 types of AKI?

Answer 5

Prerenal (most common)
Intrinsic AKI
Postrenal

Question 6

What are causes of pre renal AKI?

Answer 6

Anything that drops arterial BP or renal perfusion:

• hypovolemia
• CHF
• Hypotension
• Renal artery obstruction
• Cirrhosis

Question 7

What two medication classes can precipitate pre-renal AKI?

Answer 7

ACE-Is: vasodilator the efferent arteriole

NSAIDs: constrict afferent arteriole

Question 8

What is the pathophysiology of pre renal AKI

Answer 8

Decrease in renal blood flow drops GFR and lowers the amount of toxins filtered out of the body by the kidneys

Question 9

How does bicarb treat hyperkalemia?

Answer 9

Drives it back into cells

Question 10

What BUN:Cr ratio is observed in pre renal AKI

Answer 10

Greater than 20:1, this is because the kidney can reabsorb urea and not much is filtered anyway but creatinine never gets reabsorbed at all

Question 11

What is FENa?

Answer 11

amount of sodium filtered in the glomerulus divided by sodium excreted in urine. normal is right around 1% or slightly less

Question 12

Most common cause of intrinsic AKI

Answer 12

Acute tubular necrosis resulting from renal ischemia (long term sequelae of pre renal AKI)

Question 13

Why does rhabdomyolysis cause intrinsic AKI

Answer 13

myogloblin from muscle breakdown is toxic to tubular cells in the kidneys

Question 14

Which two antibiotics are toxic to renal parenchyma?

Answer 14

Aminoglycosides

Vancomycin

Question 15

What is the BUN:Cr ratio in intrinsic AKI

Answer 15

less than 20:1 because less urea is reabsorbed and almost as much urea is excreted as creatinine

Question 16

How is urine osmolality different between pre renal and intrinsic AKI?

Answer 16

Urine Osmolality is increased in pre renal because the still healthy tubular cells will absorb water and concentrate urine. It is increased in intrinsic AKI because of diseased tubular cells.
Prerenal: greater than 500mOsm/kg
Intrinsic: less than 350mOsm/kg

Question 17

What kind of intrinsic AKI can cause a rise in protein to 3+ or 4+?

Answer 17

Damage to the glomerulus: acute glomerulonephritis

To a lesser degree acute interstitial nephritis but less common

Question 18

What is suspected with muddy brown or granular casts?

Answer 18

ATN

Question 19

What is suspected with RBC casts

Answer 19

glomerular disease

Question 20

What is suspected with WBC casts

Answer 20

Parenchymal inflammation: pyelonephritis or interstitial nephritis

Question 21

Most common cause of chronic kidney disease

Answer 21

Diabetes Mellitus

Question 22

What is considered chronic kidney disease

Answer 22

3 months of GFR less than 60mL/min

or 3months of kidney damage of some kind