Nephro - Acute Kidney Injury - Online MedED

Question 1

AKI divided into 3:

Answer 1

Prerenal
Intra-renal
Postrenal

Question 2

Prerenal is due to:

Answer 2

Loss
Third space
Clogged vessels

Question 3

Postrenal is:

Answer 3

Obstruction - hydroureter, hydronephrosis

Question 4

Intrarenal is:

Answer 4

Look at nephron: glomerulus, tubules, interstitium (space in between)

Question 5

Prerenal differential

Answer 5

Problems with pump: MI, CHF
Leaky: nephrosis, nephrotic syndrome, gastritis, cirrhosis, nutrition go down (less albumin)
Hole: diarrhea, dehydration, diaphoresis, hemorrhage
Clog: fibromuscular dysplasia (young female), renal artery stenosis (old male)

Question 6

Postrenal differential

Answer 6

Ureters: cancer, stones
Bladder: cancer, stones, neurogenic bladder/spinal cord injury
Urethra: cancer, stones, BPH, tight foley, etc.

Question 7

Intrarenal differential

Answer 7

Glomerulonephritis

Question 8

Glomerulonephritis - urine

Answer 8

RBC casts - rule out nephrotic syndrome (>3/5 g protein/day, increased cholesterol, edema)

Question 9

Acute interstitial nephritis - urine

Answer 9

Look for WBC casts (-itis is inflammation), eosinophils

-Look for reaction to antibiotics (TMP-SMX, penicillins, cephalosporins)

Question 10

Acute tubular nephrosis - urine

Answer 10

Things in tubule that come into contact
Muddy brown casts (not sensitive or specific)
Ischemia
Exposure to toxins (IV contrast, myoglobin from rhabdo)
- Treatment is vigorous IVF

Question 11

What are the 3 phases of acute tubular nephrosis?

Answer 11

1) Prodrome of Cr rise
2) Oliguric phase (urine output tanks)
3) Polyuric phase (urine output excessive)

Question 12

What is nephrotic syndrome

Answer 12

> 3.5 g protein/day
Cholesterol
Edema

Question 13

Elevated Cr - what is the diagnostic approach

Answer 13

1) Start with rule out pre-renal - BUN/Cr ratio, Urine Na, Fractional excretion of Na, if on diuretic cannot use FeNa, use fractional excretion of urea instead
-If it is pre-renal:
BUN/Cr ratio > 20
Una < 10
FeNa < 1%
FeUrea < 35%

Question 14

So what do you do if you determine patient is pre-renal

Answer 14

Volume down - give IVF

Volume up - give diuresis

Question 15

So first step in elevated Cr is to rule out pre-renal… what to do next?

Answer 15

Rule out post-renal/obstruction

Use US/CT scan - hydroureter/hydronephrosis

Question 16

What happens if determine post-renal

Answer 16

Put in Foley, nephrostomy (at level of ureter), surgery

Question 17

After rule out pre renal and post renal… need to go to intrarenal (this is diagnosis of exclusion)

Answer 17

Use Hx and Px exam
Look at urinalysis 
Get diagnosis 
i.e. diabetic patient with glucose and protein - diabetic nephrophaty
i.e. HTN with elevated Cr - due to HTN
Might need to get Bx to prove dx

Question 18

What are the acute indications for hemodialysis?

Answer 18

Acidosis
Electrolysis - K and Ca
Intoxication
Overload
Uremia