Acute Kidney Injury

Question 1

Technical Definition of AKI

Answer 1

Within 48 hours, abrupt decline in kidney function including one of the following…

Serum creatinine increases >0.3mg/dL
Serum creatinine increases 50%
Oliguria of less than 0.5 mL/kg/hr for over 6 hours

Question 2

3 general categories for AKI Causes

Answer 2

Prerenal
Intrinsic Renal
Postrenal

Question 3

What are the 2 most common causes of AKI?

Answer 3

Prerenal azotemia

Ischemic ATN

Question 4

List some causes of Prerenal Azotemia

Answer 4

Absolute or relative decrease in ECV

Vascular stenosis or occlusion

Impaired renal autoregulation (with low ECV state)

Question 5

Describe the two primary mechanisms of renal autoregulation. Which drugs could interrupt each process?

Answer 5

Afferent arteriole vasodilation (inhibited by NSAIDs)

Efferent arteriole vasoconstriction (inhibited by ACEIs or ARBs)

Question 6

What is the biggest cause of postrenal failure?

Answer 6

Obstruction

Question 7

What are some risk factors for postrenal failure?

Answer 7

Old men with prostate disease
Solitary kidney
Intraabdominal cancer

Question 8

How to diagnose postrenal failure?

Answer 8

Physical exam
Renal ultrasound
Measurement of post void residual volume

Question 9

What are some causes of Intrinsic Renal Failure?

Answer 9

Vascular (malignant HTN)
Acute glomerular diseases
AIN (drug associated or not)
ATN (Ischemic or nephrotoxic)

Question 10

What are the most common causes of ATN?

Answer 10

Sepsis
Surgery
Nephrotoxic exposure (ABX, recreational drugs, hemoglobinuria, myoglobinuria, tubular proteins or crystals)

Question 11

Describe the pathogenesis of ATN.

Answer 11

First, see dirty or muddy brown urine.

Enter an oliguric phase, then a polyuric phase during recovery

Question 12

What is malignant HTN?

Answer 12

BP > 180/120 with impending/progressive end organ damage

HTN encephalopathy
Intracerebral hemorrhage
ACS
LV dysfuntion
Aortic dissection
Eclampsia

Question 13

What are the two general categories of acute glomerular disease?

Answer 13

Nephrotic syndrome

Nephritic syndrome

Question 14

Describe some basic characteristics of nephritic syndrome

Answer 14

Hematuria, maybe a little proteinuria

Tends to have inflammation

Active urinary sediment (cells and casts present)

Question 15

Describe some basic characteristics of nephrotic syndrome

Answer 15

Proteinuria

No inflammatory component

Question 16

Acute Interstitial Nephritis (AIN) is most commonly caused by what?

Answer 16

Drugs (PPIs, ABX, NSAIDs)

Infections

Question 17

What is the classic triad of AIN symptoms?

Answer 17

Fever
Rash
Peripheral eosinophilia

Question 18

Signs that a patient is in volume overload (too wet)

Answer 18

Abdominojugular reflux
S3 gallop
Ascites
Peripheral edema and rales heard

Question 19

Signs that a patient is in volume depletion (too dry)

Answer 19

Dry mucous membranes
Skin tenting
Neck veins flat at 0 degrees
Signs of shock

Question 20

BUN Creatinine Ratio >10:1 may indicate…

Answer 20

Prerenal azotemia
Increased urea load
Obstructive uropathy
Ureteroenterostomy
Decreased muscle mass

Question 21

BUN Creatinine Ratio =10:1 may indicate…

Answer 21

Normal
ATN
CKD

Question 22

BUN Creatinine Ratio

Answer 22

Decreased urea load
Inhibition of creatinine secretion
Increased creatinine load
Increased muscle mass

Question 23

What are the situations when you might consider putting a patient on dialysis?

Answer 23

AEIOU

Acidosis (severe or refractory)
Electrolyte derangement (severe hyperkalemia)
Intoxication syndrome
Overload (significant pulm edema)
Uremia

Question 24

What drugs should you be careful about using in patients at risk for AKI?

Answer 24

NSAIDs
ACEIs
ARBs

Question 25

What is the general prognosis of AKI?

Answer 25

Most people recover, but 5-16% of cases are irreversible