Acute Kidney Injury

Question 1

What elements are used to calculate the MDRD to estimate GFR?

Answer 1

• serum creatinine
• age
• female or not
• african american or not

Question 2

What elements are used to calculate the cockroft gault equation to estimate GFR?

Answer 2

• age
• ideal body weight
• serum creatinine
• female or not

Question 3

Using the microalbumin/creatinine ratio, how do you define normal, microalbuminuria, macroalbuminuria?

Answer 3

< 30 mg/g - normal
30-300 mg/g - microalbuminuria
> 300 mg/g - macroalbumuria

Question 4

Criteria for AKI

Answer 4

One of the following

• increase in serum creatinine of > 1.5 times baseline within prior 7 days
• increase in serum creatinine of > 0.3 mg/dL within 48 hours
• Urine volume < 0.5 mL/kg per hour for more than 6 hours

Question 5

Most common cause of AKI

Answer 5

Acute tubular necrosis - 45%

most often caused by hypotension/sepsis, ischemia, surgery/burns, nephrotoxins, rhabdo

Question 6

What is acute interstitial nephritis (AIN), how is it diagnosed, and how is it treated?

Answer 6

fever, rash, elevated serum and urine eosinophils
most common cause is medication, also infection, autoimmune disease, infection
Tx: immediate withdrawal of drug and supportive care are essential
- corticosteroids may be beneficial

Question 7

Drugs commonly associated with acute interstitial nephritis

Answer 7

PPI
allopurinol
cimetidine
NSAIDs
phenytoin
Diuretics - thiazides, furosemide
sulfonamides
cephalosporins, rifampin, cipro, PCN

Question 8

What is the clinical picture of nephritic syndrome?

Answer 8

• RBCs/RBC casts
• hypertension
• mild proteinuria

Question 9

What is the clinical picture of nephrotic syndrome

Answer 9

• massive proteinuria
• edema/hypoalbuminemia
• hyperlipidemia
• hypercoagulable

Question 10

When someone has postrenal AKI, what additional evaluation is warranted

Answer 10

renal US to look for hydronephrosis

Question 11

When should renal biopsy be performed in setting of AKI?

Answer 11

• Clinical findings: oliguria, rapidly worsening GFR
• cause of intrinsic injury unclear
• pre-renal and post-renal causes have been ruled out
• need for confirmation before disease specific therapies commence

Question 12

How do you manage at-risk patient before a dye study?

Answer 12

• stop metformin 48 hours before, esp if GFR < 60
• isotonic solution IV hydration
• acetyle cysteine 120 mg BID he day before and the day of exam (inconsistent data)
• high dose statins may be helpful
• alkalinize the urine (inconsistent data)

Question 13

When prescribing metformin, how do you use renal function to guide management?

Answer 13

• do not start if eGFR < 45
• at eGFR < 45 may continue previous therapy but may consider 50% reduction in dose
• do not use if GFR < 30

Question 14

When prescribing nitrofurantoin, how do you use renal function to guide management?

Answer 14

Avoid using in GFR < 60 ml/min

Question 15

What lab findings are used to calculate FENa? How do you interpret FENa?

Answer 15

FENa = 100 x (urine Na X Plasma Cr)/(plasma Na x Urine Cr)
prerenal = < 1 %
renal = 1-2%
ATN = > 2-3%

Question 16

components of FeUrea

How do you interpret it?

Answer 16

BUN, serum cr, urine urea, urine creatinine
FeUrea < 35% - prerenal
FeUrea > 50% - ATN

Question 17

How do you calculate mean arterial pressure (MAP)?

Answer 17

MAP = (systolic + 2x diastolic)/3

Question 18

Treatment of AKI with volume overload

Answer 18

Lasix IV Q6 is initial tx
If inadequate response after 1 hr double the dose
repeat until adequate urine output

Question 19

Treatment of hyperkalemia

Answer 19

• IV calcium gluconate (cario protective/membrane stabilizer)
• Shift K into cells: insulin (10 units IV and glucose 25 gm), albuterol, sodium bicarb (3 amps in 1 L of 5% dextrose
• eliminate: Oral or rectal Kayexelate

Question 20

In acidosis, what lab finding would prompt you to initiate sodium bicarb

Answer 20

Serum bicab < 15 mEq/L or pH < 7.2

Question 21

What are indications for emergent dialysis in patients with AKI?

Answer 21

• metabolic acidosis: ph < 7.1
• Uremia: pleuritis, pericarditis, neuropathy, encephalopathy/aMS
• fluid overload refractory to diuretics
• Hyperkalemia: K > 6.5 of rapid rise
• poisoning

Question 22

What level of metabolic acidosis should prompt urgent dialysis in renal failure?

Answer 22

• metabolic acidosis: ph < 7.1

Question 23

What potassium level should prompt urgent dialysis in renal failure?

Answer 23

• Hyperkalemia: K > 6.5 of rapid rise

Question 24

What is Cardiorenal syndrome type I?

Answer 24

Acute CHF causes acute AKI

Question 25

What is Cardiorenal syndrome type II?

Answer 25

Chronic cardiac dysfunction causes progressive CKD

Question 26

What is Cardiorenal syndrome type III?

Answer 26

AKI causes acute cardiac dysfunction

Question 27

What is Cardiorenal syndrome type IV?

Answer 27

Primary CKD contributes to cardiac dysfunction - CAD, CHF, or arrhythmia

Question 28

What is Cardiorenal syndrome type V?

Answer 28

acute or chronic systemic disorders cause both cardiac and renal dysfunction - sepsis or diabetes

Question 29

What is the mechanism of an ACE inhibitor?

Answer 29

blocks conversion of Angiotensin 1 to angiotensin 2

• Lowers arteriolar resistance
• increase venous capacity
• prevents aldosterone secretion from adrenal gland (which ends up preventing sodium retention)
• prevents vasopressin release from the posterior pituitary ( which ends up preventing H2O retention at distal tubule
• causes central enhancement of parasympathic activity, breaks sympathetic system activation, reduces plasma NE

Question 30

What change in creatinine is tolerable after administration of ACE-I/ARB?

Answer 30

20-30% increase in cr which then stabilizes represents hemodynamic change, not structural change