2.2.1 Acute Kidney Injury

Question 1

What are some of the various causes of pre-renal kidney injury?

Answer 1

Low CO

Renal artery stenosis

Decreased intravascular volume (blood loss, dehydration)

Decreased systemic vascular resistance (sepsis, cirrhosis)

Question 2

Taking what type of medication can alter FeNa?

Answer 2

Diuretic medications

Question 3

Determine the source of the AKI and how to treat it, doc

Answer 3

Renal US - distended bladder w/ bilateral hydronephrosis; Post-renal AKI secondary to bladder outlet obstruction from prostate cancer

Treat: Indwelling Foley

Question 4

Determine the source of the AKI and how to treat it, doc

Answer 4

Pre-renal AKI secondary to intravascular fluid depletion (dehydration

IV fluids

Question 5

What are the three main subclasses of intrinsic (interstitial) AKI?

Answer 5

Allergic, infectious, infiltrative

Question 6

What are the four different types of intra-renal (intrinsic) AKI?

Answer 6

Large vessels, small vessels, tubules, interstitium

Question 7

What are the three sites of kidney injury and their corresponding prevelance?

Answer 7

Pre-renal injury (55%)

Intra-renal (40%)

Post-renal (5%)

Question 8

What term is synonymous with AKI?

Answer 8

Acute Renal Failure (ARF)

Question 9

What is the most common intrinsic (tubular) AKI?

Answer 9

Acute tubular necrosis (ATN)

Question 10

This microscopic finding is consistent with what type of disease?

Answer 10

Interstitial Disease

Question 11

What are two different sources of intrinsic (small vessel) AKI?

Answer 11

Glomerulonephropathies - damage to GBM

Small vessel occlusion - HTN, coagulopathies, embolic dz

Question 12

What is the most common cause of post-renal AKI?

Answer 12

Bladder neck obstruction

Question 13

What are some symptoms that are consistent with AKI?

Answer 13

Generalized fatigue, nausea and anorexia, itching

Question 14

Determine the source of the AKI and how to treat it, doc

Answer 14

ARN secondary to hypoxia and possibly iodinated contrast dye w/ cardiac catheterization

Treat: supportive care including oxygen, BP support, IVF

Question 15

What are 4 major complications of AKI?

Answer 15

Fluid overload

Electrolyte disorders (Na, Phos, K, Ca)

Metabolic acidosis

Mental status change (seizures)

Question 16

Describe the two renal US?

Answer 16

Left: Normal

Right: Hydronephrosis

Question 17

Determine the source of the AKI and how to treat it, doc

Answer 17

Pre-renal AKI secondary to cardiac tamponade (low CO)

Treat: Pericardiocentesis

Question 18

By definition, what is acute kidney injury (AKI)?

Answer 18

Sudden decrease in kidney function that can lead to: inability to maintain fluid balance, electrolyte disorders, inhibition of nitrogenous waste excretion

Question 19

What are three different ways to classify AKIs?

Answer 19

Duration

Amount of Urine Output

Site of Kidney Injury

Question 20

What are some systemic dz’s that can lead to glomerular injury?

Answer 20

Skin (purpura, petechiae)

GI (hematochezia, diarrhea)

Lung (pulmonary hemorrhage)

MSK (arthalgias, myalgias)

Question 21

What are some physical exam findings that are consistent with AKI?

Answer 21

Cardiac rub

Neurological deficits (asterixis, confusion, tremor)

Signs of volume overload (cardiac gallop, JVD, pulm edema, peripheral edema)

Question 22

Determine the source of the AKI and how to treat it, doc

Answer 22

Acute interstitial nephritis secondary to Cipro (key word: WBC casts)

Treat: Discontinue cipro

Question 23

What are the two different classifications of amount of urine output?

Answer 23

Oliguria: <400 mL urine/day

Anuria: <50 mL urine/day

Question 24

What are some of the indications for renal biopsy?

Answer 24

Proteinuria

Nephritic syndrome: Proteinuria, glomeular hematuria, progressive AKI, severe HTN, evidence of inflammation on urine microscopy

Unexplained AKI

Question 25

What disease has these common urine findings?

Answer 25

Glomerular Dz’s

Question 26

What are some the ways to resolve obstruction?

Answer 26

Foley catheter for bladder outlet obstruction

Ureteral stenting for ureteral obstructions

If obstruction unresolvable, percutaneous nephrostomhy tubes inserted

Question 27

What are the two inciting events that can lead to ATN?

Answer 27

Nephrotoxic Agents (endogenous or exogenous)

Ischemic states

Question 28

Which imaging study is most useful for evaluating AKI?

Answer 28

Abdominal US

Question 29

What are some of the indications for hemodialysis in acute setting?

Answer 29

HyperK w/ EKG changes

Pulmonary edema

Severe metabolic acidosis

Mental status change

Certain drug intoxications

Progressive dz w/o reversibility of underlying cause

Question 30

What are some common tests to assess kidney function?

Answer 30

Lab studies (BUN, CR, BUN:CR ratio)

Blood Test: Electrolyte abnormalities (hyperkalemia, hyperphosphatemia, metabolic acidosis)

Urine Studies (cellular elements)

Question 31

This microscopic finding is consistent with what type of disease?

Answer 31

Tubular Dz (ATN)

Question 32

What the two different sources of intrinsic (large vessel) AKI?

Answer 32

Arterial obstruction (plaque, hypertrophy of muscular layer, dissection)

Renal vein outflow obstruction (uncommon)

Question 33

What are some characteristic urine findings w/ glomerular injury? (3)

Answer 33

RBC casts, dysmorphic RBCs, proteinuria

Question 34

What is the equation for fractional excretion of sodium? Normal values?

Answer 34

FeNa = [(U_Na/P_Na) / (U_Cr/P_Cr)]

Normal value: 1-2 %

FeNa < 1% - suspect pre-renal AKI

FeNa > 3% - suspect intrinsic AKI with some degree of tubular damage