A Cute Kidney Injury.

Question 1

Risk factors for acute kidney injury (AKI)

Answer 1

Age >75
DM
Chronic kidney dz
CHF
Liver failure
Sepsis
IV contrast
Cardiac surgery

Question 2

AKI definition

Answer 2

Abrupt (within 48 hrs) decline in kidney fxn as manifested by:
Increase in serum creatinine >.3 mg/Dl
OR
Decrease in urine output <.5mL/kg/hr x 6 hr
OR
Need for dialysis

Question 3

Azotemia

Answer 3

Elevated BUN and/or Creatinine

BUild up of abnormally large waste products in the blood

Question 4

Oliguria

Answer 4

Urine output <400 mL/day

Question 5

Anuria

Answer 5

Urine output <100 mL/day

Question 6

What can lead to elevated BUN

Answer 6

Decrease in GFR

Burns, steroids, fever, GI bleed

Question 7

Prerenal AKI

Answer 7

Decreased renal perfusion

Question 8

Post-renal AKI

Answer 8

Inadequate drainage of urine distal to the kidney

Question 9

What would urine osmolality and sodium by in pre-renal failure?

Answer 9

Low sodium, low specific gravity.

Na and Water are being retained in the vasculature.

Question 10

What will the BUN/Crea ratio be in pre-renal failure?

Answer 10

Elevated.

Question 11

Prerenal tx

Answer 11

Treat underlying cause
Maintain euvolemia
Avoid nephrotoxic drugs

Question 12

Postrenal AKI

Answer 12

Reversible
Least common cause of AKi
Obstruction somewhere in kidney, ureter, bladder, urethra
Most common cause is prostatic obstruction

Question 13

Postrenal AKI etiologies

Answer 13

BPH
Anticholinergenic drugs
Cancers
Neurogenic bladder
Urethral stones or strictures

Question 14

What will the BUN/Crea ratio be in postrenal failure?

Answer 14

10 - 20:1. Normal

Question 15

Intrinsic AKI

Answer 15

Injury within the kidney

Half of all cases

Question 16

Acute Glomerulonephritis

Answer 16

Immunologic mechanism triggers inflammation and proliferation of glomerular tissue that results in damage to the BASEMENT MEMBRANE, mesangium or capillary endothelium.

Question 17

Causes of Acute Glomerulonephritis

Answer 17

Post streptococcal 
Systemic illness (SLE, wegeners)

Question 18

What will be seen in the urine in Acute Glomerulonephritis?

Answer 18

Red cell casts and significant proteinuria

Question 19

Acute interstitial Nephritis

Answer 19

Most cases related to medication use
Also caused by kidney infxn
Eosinophils in urine

Question 20

What is the most common cause of acute interstitial renal injury?

Answer 20

Acute tubular necrosis

Question 21

3 main causes of acute tubular necrosis

Answer 21

Ischemia, Sepsis, nephrotoxic drugs

Question 22

Acute tubular necrosis (ATN)

Answer 22

Occurs when tubules fail to function

Question 23

What will the urine show in acute tubular necrosis?

Answer 23

Low BUN/Crea ratio.
Elevated urine sodium, low osmolality
Muddy brown casts
Sediment in urine

Question 24

Contrast Nephropathy

Answer 24

Form of ATN
Occurs 24 - 48 hrs post-exposure
Chronic illness is a risk factor

Question 25

Contrast nephropathy prevention

Answer 25

Stop metformin the day of contrast and for 48 hrs post-contrast.
Mucomyst 3 days before

Question 26

ATN secondary to ischemia

Answer 26

Tubular damage from site of low perfusion (prerenal)

Question 27

FENa

Answer 27

Fractional excretion of sodium and urine sodium concentration
Useful for determining cause of AKI

Question 28

What will FENa show in prerenal?

Answer 28

<1%

Question 29

What will FENa show in intrinsic?

Answer 29

> 2%

Question 30

Dark granular and epithelial casts =?

Answer 30

Pure ATN

Question 31

Crystals in urine =?

Answer 31

Crystalluric ARF

Question 32

WBC and WBC casts in urine =?

Answer 32

Acute interstitial nephritis

Question 33

RBC’s and RBC casts =?

Answer 33

Necrotizing glomerulonephritis

Question 34

Hydronephrosis

Answer 34

Seen on ultrasound

Shows obstruction

Question 35

CT or MRI will show

Answer 35

Kidney stone, kidney size