Acute Kidney Injury

Question 1

How is AKI staged?

Answer 1

Stage 1-3

• based on serum creatinine or urine output, whichever is worse

Question 2

What is the most common cause of AKI? (2)

Answer 2

1. Prerenal azotemia

2. Acute tubular necrosis

Question 3

What can cause acute tubular necrosis? (cause of AKI)

Answer 3

1. ischemia
2. Toxins
   • Antibiotics
   • IV iodine contrase dye
   • heme pigments
   • light chains from myosin

Question 4

What is activated from prerenal azotemia?

Answer 4

Prerenal azotemia activates RAAS and ADH

• RAAS and ADH cause a decrease urine output to restore ECV

Question 5

What is FeNa in prerenal azotemia?

Answer 5

FeNa<1%

Question 6

What is FeNa in ATN?

Answer 6

> 2%, cells are damaged

Question 7

What parts of the kidney receive the most and least blood?

Answer 7

• Renal Cortex receives the most blood

- Renal medulla is a watershed area susceptible to ischemia

Question 8

What parts of the kidney have the highest metabolic activity?

Answer 8

Proximal tubule and thick ascending limb ( both in medulla susceptible to ischemia)

Question 9

Why would you see a decreased GFR in acute tubular necrosis?

Answer 9

1. Tubule is obstructed from the formation of casts

2. Urine leaks back because tight junctions are lost

Question 10

How can you distinguish prerenal azotemia from ATN

Answer 10

-Prerenal azotemia has bland urne with hyaline casts

• ATN has UA with
  1. hyaline casts
  2. renal tubular epithelial cells
  3. transitional epithelial cells
  4. granular casts

PRERENAL AZOTEMIA WILL RESOLVE WITH NORMAL SALINE TX

Question 11

What drugs can cause interstitial nephritis?

Answer 11

1. NSAIDs
2. Antibiotics
3. PPIs

Question 12

What labs/ diagnostic test should be ordered on all patients with AKI?

Answer 12

1. Urinalysis with microscopy
2. Urine Albumin/Creatinine ratio or urine protein/creatinine ratios
3. renal U/S

Question 13

What 2 renal US signs suggest CKD?

Answer 13

1. cortical thinning

2. Small kidneys

Question 14

Why would you order FeNa or FeUrea?

Answer 14

To differentiate prerenal azotemia from intrinsic renal injury (ATN)

Question 15

FeNa/ FeUrea is only valid for what type of patients?

Answer 15

Oligurua <400-500 ml per day ( more than 100)

Question 16

Why do urea levels increase in dehydration?

Answer 16

In dehydration (prerenal azotemia) ADH is secreted–> ADH binds V2 receptors in basolateral membrane–> increases intracellular cAMP–> leased to insertion AQP and urea on the apical membrane –> increased absorption of urea

BUN/Cr ration is >20:1 in prerenal azotemia

Question 17

• Renal tubular epithelial cells
• transitional epithelial cells
• granular casts
• waxy casts

is the urinary pattern seen when?

Answer 17

Acute tubular necrosis

Question 18

WBC, WBC cast, or urine eosinophils are seen in urine when?

Answer 18

• Acute interstitial nephritis

- Pylonephritis

Question 19

Dysmorphic RBCs and RBC casts are seen in urine when?

Answer 19

• vasculitis

- glomerulonephritis

Question 20

-Proteinuria <3.5 g.day
-hematuria
-dysmorphic RBC
-RBC casts
are seen when?

Answer 20

Nephritic syndrome

Question 21

Heavy proteinuria >3.5 g/day

• lipiduria
• minimal hematuria

are seen in urine when?

Answer 21

Nephrotic syndrome

Question 22

Hyaline casts are seen in urine when?

Answer 22

Prerenal azotemia

-nonspecific sign

Question 23

WBCs, RBS, and bacteria would be seen in urine when?

Answer 23

UTI

Question 24

What are the indications for dialysis?

Answer 24

AEIOU
A: Severe Acidosis
E:Electrolyte disturbance
I: Ingestion
O:volume overload
U:Uremia

Question 25

What is the expected recovery time of AKI?

Answer 25

Most recover some degree of renal function within 7-21 days

if they don’t recover in 3 months–> they have CKD