Acute Renal Failure- Florescu

Question 1

Definition of acute kidney injury

Answer 1

Abrupt (w/i 48 hours) reduction in kidney function defined as:

• An absolute increase in creatinine of >0.3 mg/dL or a percentage increase more than 50%
• Or a reduction in Urinary Output (UOP) (<0.5 ml/Kg/h for more than 6 hours)

Question 2

Major cause of acute renal failure in hospital setting

Answer 2

Acute tubular necrosis

Question 3

Prerenal presentation and treatment

Answer 3

Normal physiologic response to renal hypo perfusion to impair GFR. Renal parenchyma is normal. If not treated can lead to ATN.
Treat: Fluid repletion

Question 4

Rate of rise of plasma creatinine in ATN vs. Prerenal

Answer 4

ATN: rise progressively at a rate greater than 0.3 to 0.5 mg/dL per day.
Prerenal disease: Slower rate of rise with periodic downward fluctuation

Question 5

UA in ATN and Prerenal

Answer 5

• Normal in Prerenal disease

- In ATN: Muddy brown granular and epithelial cell casts and free epithelial cells.

Question 6

Fractional excretion of sodium (FENa) in prerenal and ATN

Answer 6

Prerenal disease: 2%

Question 7

Fractional excretion of urea (FEurea) in prerenal patients

Answer 7

<35%

Question 8

Diagnosis of Prerenal Azotemia

Answer 8

• Normal renal US
• UA-normal
• Low urine Na, FENa<35%
• No proteinuria, no albuminuria
• Reversible with hydration

Question 9

Glomerular Disease as a cause of Acute Kidney Injury presentation

Answer 9

• Most of time rapidly progressive GN
• Normal Renal US- large kidney
• UA- hematuria, RBC CASTS, dysmorphic RBCs
• Proteinuria ~1-2 g/day
• FENa can be <1%

Question 10

Tubular Diseases- ATN presentation

Answer 10

Renal US: Normal
UA: Muddy brown granular casts, epithelial cell, epithelial cell casts, hematuria- no dysmorphic RBCs
-Subnephrotic proteinuria
-FENA >2%

Question 11

ATN management

Answer 11

Conservative: Avoid hypotension, fluid depletion, nephrotoxic medication. Use renal replacement therapy when needed (dialysis).

Question 12

Interstitial Kidney Disease presentation

Answer 12

-Symptoms and/or signs of allergic-type reaction: Rash, fever, eosinophilia, or triad of three
-Renal US: normal
-UA: White cells, red cells, WBC casts. Mild increase in protein. EOSINOPHILURIA (75% in 1st week).
-Nephrotic syndrome due to minimal change disease can be seen with NSAIDS
FENa >2%

Question 13

AIN- Acute interstitial nephritis causes

Answer 13

Drugs with antibiotics responsible for 1/3 of these cases.

• Infection related
• Idiopathic
• Tubulointerstitial nephritis and uveitis syndrome
• sarcoidosis

Question 14

AIN management

Answer 14

Identify and stop medication causing disease.

-Severe: prednisone- make sure infection has been excluded before starting therapy

Question 15

Tests to be ordered with acute renal failure

Answer 15

1) Renal Ultrasound with Doppler
2) UA with microscopic exam
3) Spot urine proteins/creatinine ratio
4) Spot urine albumin/ creatinine ratio
5) Urine Na, urea

Question 16

Postrenal causes

Answer 16

• Ureteral obstruction
• Bilateral ureteral obstruction (stone, retroperitoneal fibrosis, pelvic masses)
• Urethral obstruction: BPH, Prostate cancer

Question 17

Renal US with Doppler can tell you…

Answer 17

• Kidney size
• Renal perfusion
• Measures the resistive indexes
• Renal echogenicity
• Ureteral obstruction
• Bladder obstruction, masses, postvoid residue
• prostate size and shape
• possible other organs pathology

Question 18

Increased renal echogenicity seen often in what?

Answer 18

Chronic renal disease

Question 19

UA with microscopic exam:

1) Glomerular problem
2) Prerenal
3) ATN

Answer 19

1) Hematuria (dysmorphic RBC) and proteinuria
2) Normal
3) Muddy brown granular casts

Question 20

Urine protein/creatinine and urine albumin/creatinine for glomerular (not NS), ATN, Interstitial disease

Answer 20

1-3.5 g of proteins/day

Question 21

> 3.5 g protein/day is

Answer 21

NS or nephrotic range proteinuria

Question 22

Indications to start RRT (Dialysis)

Answer 22

• Severe acidosis
• Severe hyperK
• Fluid overload not responding to diuretics
• Uremic symptoms
• Uremic pericarditis
• BUN ~80 mg/dL