Acute Renal Failure

Question 1

Acute Renal Failure is defined as…

Answer 1

Increased serum creatinine by at least…
- 0.3 mg/dL within 48 hours
- Increase by 1.5 times within a week
Urine volume under .3mL/kg/hr for more than 6 hrs

Question 2

What exactly is Creatinine

Answer 2

Breakdown product of creatine phosphate in muscle
Usually produced at fairly constant rate (depending on body mass)
Filtered, but not reabsorbed

Question 3

Three types of AKI

Answer 3

Prerenal, Renal, Postrenal

Question 4

Complete renal shutdown occurs when…

Answer 4

Serum creatine level rises at least .5 mg/L/day

Urine output under 400 mL per day

Question 5

If you had to guess blindyly one of the three causes of ARF, which would you pick

Answer 5

Prerenal in 60-70% of cases

Question 6

Symptoms of ARI

Answer 6

Anorexia, Vomiting, Diarrhea
Fatigue
Mental Status Changes/Seizures
Shortness of Breath (if volume overloaded)

Question 7

Two broad physioogical categories of prerenal acute failute

Answer 7

Intravascular volume depletion

Decreased effective circulating volumes to the kidneys (CHF, Cirrhosis, hypoalbuminemia, hypotension)

Question 8

Drugs that inhibit renal bloodflow

Answer 8

ACEi, ARBs – inhibit efferent arteriolar constriction
NSAIDS – inhibit vasodilating prostaglandins
Direct vasodilators – decrease renal bloodflow prior to glomerulus ?

Question 9

Physical Exam findings associated with ARI

Answer 9

BP alterations
Dehydration, distended jugular
Asterixis and Myoclonus

Question 10

Lab findings associated with Prerenal ARF

Answer 10

Bland urine sediment
Urine osmolarity over 500 mOsm
BUN:Creatinine ration above 20:1
Fractional excretion of sodium under 1%

Question 11

How is fractional excretion of sodium determined

Answer 11

100 x (urine sodium/serium sodium) / (Urine cre./Serum Cre.)

Question 12

Relationship of CHF to ARF

Answer 12

CHF –> decreased renal blood flow (overdiuresis) or decreased cardiac output

Question 13

Four types of intrinsic acute renal failure

Answer 13

Tubular, Glomerular, Vascular, Interstitial

Question 14

Three phases of Acute Tubular Necrosis

Answer 14

1. Initiation Phase (hrs-days)
2. Maintenence Phase (GFR hits low point)
3. Recovery Phase (Diuresis, worry about hypovolemia)

Question 15

Casts especially associated with Acute Tubular Necrosis

Answer 15

Muddy, Brown Casts

Question 16

Toxins that cause ATN

Answer 16

Endogenous – Myoglobin (think rhabdo)

Exogenous – Iodinated Contrast Dye, Aminoglycosides

Question 17

Classic findings of Acute Interstitial Nephrosis

Answer 17

Fever, Rash, and Arthralgias

Could also lead to cystitis, pyelonephritis

Question 18

Two types of glomerular nephritis

Answer 18

Rapidly Progressive Glomerulonephritis

Acute Proliferative Glomerulonephritis

Question 19

Causes of Rapidly Progressive Glomerulonephritis?

Answer 19

Systemic Lupus/Autoimmune disease

Small Vessel Vasculitis

Question 20

Important types of vascular disease associated with glomerulonephritis

Answer 20

Atheroembolic disease

Thrombotic Thrombocytopenic Purpura, HUS

Question 21

TTP/HUS is a problem where? treatment?

Answer 21

Where – In small vessels leading up to Glom.

Can treat with plasmaphoresis

Question 22

Interstitial disease causes?

Answer 22

Allergic Rxn to drugs
Autoimmune (SLE)
Pyelonephritis
Infiltrative Disease

Question 23

Sources of postrenal acute renal failure

Answer 23

BPH/Prostate Cancer
Cervical Cancer
Retroperitoneal Disorders
Pelvic obstruction/Bladder Mass
Urethral strictures

Question 24

_________ may be diagnostic and therapeutic in patients with post-renal ARF

Answer 24

Bladder catheterization

Question 25

How to diagnose a patient with post-renal ARF

Answer 25

Renal Ultrasound

Question 26

Tx for Post-Renal ARF

other then FINDING AND TREATING THE CAUSE

Answer 26

Bladder Cath
Percutaneous nephrostomy
Ureteral Stenting
Lasix if fluid overloaded
Last resort --> Dialysis