Essentials of Pathophysiology
CHAPTER 26
ACUTE RENAL FAILURE AND
CHRONIC KIDNEY DISEASE
PRE LECTURE QUIZ TRUE/FALSE
F
T
T
F
F
Acute renal failure is not a reversible process.
 Chronic renal failure leads to hyperkalemia
and the risk for cardiac arrhythmias.
 Exposures to nephrotoxic drugs, heavy metals,
and organic solvents are possible causes of
intrinsic or intrarenal acute renal failure.
 During chronic renal failure, the activation of
vitamin D is increased.
 Dietary management is a minor component in
the treatment of chronic renal failure.

PRE LECTURE QUIZ

__________ failure, the most common form of acute
renal failure, is characterized by a marked decrease in
renal blood flow.
azotemia

An accumulation of nitrogenous waste products in the
blood is called __________.
Prerenal

__________, which literally means “urine in the blood,”
is the term used to describe the clinical manifestations
of renal failure.

Sodium and water imbalance that results from chronic
renal failure contributes to an increased vascular
volume, which leads to edema and __________,
eventually contributing to heart failure.

Chronic __________, the most profound hematologic
alteration that accompanies renal failure, is due to the
decreased production of the hormone______________
anemia
hypertension
Uremia
Erythropoietin
WHEN KIDNEYS FAIL



Less waste is removed
More waste remains in the blood
Nitrogenous compounds build up in the blood







BUN: Blood urea nitrogen
Creatinine
Renal function approximated by:
initial creatinine level ÷ current creatinine level
BUN/Creatinine should/be approx 10
If >15 suggest non renal cause of Urea Elevation
If < 10 Possible liver disease
If both go up in ratio it suggests Kidney failure
Typical Renal Failure Modes
ACUTE RENAL FAILURE

Prerenal
 Decreased
 Shock,

dehydration, vasoconstriction
Postrenal
 Urine
flow is blocked
 Stones,

blood supply
tumors, enlarged prostate
Intrinsic
 Kidney
tubule function is decreased
 Ischemia,
toxins, intratubular obstruction
QUESTION
Which type of acute renal failure (ARF) would be
most likely to accompany benign prostatic
hypertrophy?
a. Prerenal
b. Postrenal
c. Intrinsic
d. Extrinsic
ANSWER
b. Postrenal
Postrenal ARF occurs when the flow of urine is
blocked by kidney stones, tumors, or an
enlarged prostate gland. Because the male
urethra passes through the prostate, if it is
enlarged, the urethra may become blocked.
RADIOCONTRAST AGENTS CAN CAUSE ARF


Giving N-acetylcysteine reduces the risk of ARF by
50% in a meta-analysis
Recommended for clients at risk of renal failure
who are receiving radiographic contrast media
 Diabetics, clients with sepsis
 Underlying vascular, renal, or hepatic disease
 Receiving other nephrotoxic drugs
(Kellum, J.A. [2003]. A drug to prevent renal failure? Lancet 362,589-590.)
SCENARIO
A man developed acute renal failure after
emergency surgery for a severed left leg
 He came in with a serum creatinine of 1.2
mg/dL, but now it is 5.6 mg/dL
 His BUN is 86 mg/dL (7-20 mg/dl = Normal)

Produced by the liver when protein is digested & cleared by the Kidneys
Question:
 Why would leg damage cause renal failure?
 What is his remaining kidney function? (next Slide)
SCENARIO CONT.
Current Creatine / initial creatine
5.6/1.2= 4.7
URINE CONTAINING TUBULAR CELL CASTS



Casts are formed
when cells are
packed together in
the tubule lumen
They block the
tubule
When the mass of
cells washes loose,
it appears in the
urine
SCENARIO
Mr. J is an alcoholic with kidney problems
 He is severely dehydrated with an infected leg
ulcer, benign prostatic hypertrophy, and
anemia
 His urine is dark and contains myoglobin and
tubular cell casts
 His creatinine and BUN are both elevated
Question:
 What may have caused his acute tubular
necrosis?
CHRONIC RENAL FAILURE


Fewer nephrons are functioning
Remaining nephrons must filter
more
 Hyperperfusion
 Hypertrophy
DEVELOPMENT OF CRF




Diminished renal reserve
 Nephrons are working as hard as they can
Renal insufficiency
 Nephrons can no longer regulate urine density
Renal failure
 Nephrons can no longer keep blood composition
normal
End-stage renal disease
UREMIA




Uremia = “Urine in the Blood”
Renal filtering function decreases
 Altered fluid and electrolyte balance
o Acidosis, hyperkalemia, salt wasting,
hypertension
Wastes build up in blood
 Increased creatinine and BUN
o Toxic to CNS, RBCs, platelets
Kidney metabolic functions decrease
 Decreased erythropoietin
 Decreased Vitamin D activation
VITAMIN D ACTIVATION
Vitamin D obtained from sun exposure, food,
and supplements is biologically inert and
 must undergo addition of 2 –OH groups in the
body for activation.
 The first occurs in the liver and converts
vitamin D to calcidiol.
 The second occurs primarily in the kidney and
forms calcitriol
 Calcitrol is necessary for absorption of Ca2+ by
the small intestine.

POLYCYSTIC KIDNEY DISEASE (PKD)
Normal
QUESTION
Which of the following renal disorders is
characterized by increased BUN and creatinine
levels?
a. ARF
O
||
b. CRF
C
/ \
c. Uremia
NH2 NH2
d. All of the above
UREA
e. b and c
ANSWER
d.
All of the above
In each disorder listed, the ability to remove
nitrogenous waste is diminished. This causes
nitrogenous compounds (BUN and creatinine)
to accumulate in the blood.
SCENARIO
A man has chronic renal failure.
 He has high creatinine and BUN, hyperkalemia,
acidosis with normal pCO2, and severe anemia
 His blood glucose has reached 340 mg/dL one
hour after a hospital meal
 He complains of having broken two toes in the last
few weeks, even though he eats a lot of dairy
products for calcium
SCENARIO (CONT.)
Question:
 What is the most likely cause of his
chronic renal failure?
 What caused his anemia?
 Why are his bones brittle even though he
eats dairy products?
CARDIOVASCULAR CONSEQUENCES OF CRF



Decreased blood
viscosity
+
Increased blood
pressure
+
Decreased oxygen
supply
less
erythropoietin
anemia
lower blood
viscosity
blood flows through
vessels more swiftly
heart rate increases
CARDIOVASCULAR CONSEQUENCES OF CRF
increased workload on left heart
left ventricle dilation and
hypertrophy
not enough oxygen to support LV
contraction
angina
ischemia
LHF
QUESTION
Tell whether the following statement is true or
false.
CRF leads to decreased cardiac output (CO).
ANSWER
True
The increased blood pressure (HTN) and
hypoxemia that accompany CRF lead to
increased myocardial work (the heart has to
work harder to meet the metabolic demands of
body tissues). Eventually the heart becomes
unable to meet these metabolic demands, and
CO will decrease.
MANIFESTATIONS OF KIDNEY FAILURE
TYPES OF DIALYSIS