Renal failure

Question 1

Acute kidney injury

Answer 1

Injury or dz of kidneys
Sudden decline in renal function

Increase BUN/Cr

Azotemia – elevated BUN

Question 2

Pre-renal azotemia

Answer 2

BUN/Cr of >20:1

Underperfusion *

Hypovolemia
CHF, low EF
Portal HTN
Sepsis
Cardiac arrest
Excessive NSAID use

Attempt to increase BP d/t underperfusion
FEna less than 1%
Urine Na less than 20 mEq/L

Question 3

Intrinsic renal disease

Answer 3

BUN:Cr 10-15:1

Glomerulonephritis
Acute tubular necrosis
Acute interstitial nephritis

Urine Na over 40 mEq/L
FEna >2%

Question 4

Postrenal azotemia

Answer 4

Urinary obstruction – b/l
Prostate dz – BPH
Neoplasms
Congenital anomalies
Kidney stones

Dx: labs variable

Imaging:
Hydronephrosis
Dialted ureters
Bladder distention

Question 5

Fraction excretion of sodium (FEna)

Answer 5

100 x ( Una x Scr)/(Sna x Ucr)

Small numbers/big numbers

Question 6

Results of renal failure

Answer 6

Volume overload
Hyperkalemia (life threatening*), hyperphosphatemia
Metabolic acidosis
Metabolic bone disease – renal osteodystrophy
Anemia
Uremia: (anorexia, N/V, skin changes, pericarditis, platelet dysfxn, encephalopathy)
Hypertriglyceridemia

Question 7

Renal osteodystrophy

Answer 7

Kidney not activating vit D efficiently -> low Ca2+ absorption in GI

PTH released -> bone resorption

Tx: calcium and vit D supplements

Question 8

Ischemia causes of acute tubular necrosis (ATN)

Answer 8

Prolonged hypotension
Sepsis
Blood loss
Surgery – AAA
CHF

Question 9

Nephrotoxins causing acute tubular necrosis

Answer 9

Drugs: aminoglycosides, cisplatin
Radiocontrast
Myoglobin – rhabdomyolysis
Syntehtic cannabinoids – K2 or spice

Question 10

Acute tubular necrosis

Answer 10

Epithelial cells damage

MC: AKI esp in hospitalized pts

BUN/Cr elevated weeks after despite correcting primary insult

Bx: sloughing of tubular cells into lumen
Muddy brown casts in urine

Question 11

Acute interstitial nephritis (AIN)

Answer 11

Drug induced
Allergic

Classic presentation:
Fever
Eosinophilia
Azotemia
Rash

MC drugs:
NSAIDs
PCNs and cephalosporins
Ciprofloxacin
Rifampin
Sulfonamides (TMP-SMX)
Diuretics
PPIs
Cimetidine
Allopurinol

Tx: stop drug, steroids x 2 wks w/ taper

Question 12

Renal papillary necrosis

Answer 12

Ischemia -> necrosis and sloughing of renal papillae

Gross hematuria +/- flank pain
Azotemia
HTN

Causes:
Pyelonephritis
Analgesics – acetaminophen, possibly NSAIDs
DM
Sickle cell dz

Question 13

Diffuse cortical necrosis

Answer 13

Acute generalized cortical infarction of b/l kidney
Pregnancy
-complications of placental abruption
-amniotic fluid embolism
-massive hemorrhage

• > arterial vasospasm -> renal ischemia
• > DIC

flank pain
hematuria and oliguria
anuria