CHAPTER 26ACUTE RENAL FAILURE AND CHRONIC KIDNEY DISEASE
Essentials of Pathophysiology
PRE LECTURE QUIZ TRUE/FALSE
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.
F
T
T
F
F
PRE LECTURE QUIZ __________ failure, the most common form of acute
renal failure, is characterized by a marked decrease in renal blood flow.
An accumulation of nitrogenous waste products in the blood is called __________.
__________, 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
azotemia
Prerenal
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 blood supply
Shock, dehydration, vasoconstriction Postrenal
Urine flow is blocked Stones, 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. Prerenalb. Postrenalc. Intrinsicd. 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.
5.6/1.2= 4.7
Current Creatine / initial creatine
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 balanceo Acidosis, hyperkalemia, salt wasting,
hypertension Wastes build up in blood
Increased creatinine and BUNo 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. ARFb. CRFc. Uremiad. All of the abovee. b and c
O || C / \NH2 NH2
UREA
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
left ventricle dilation and hypertrophy
not enough oxygen to support LV contraction
anginaischemia
LHF
increased workload on left heart
CARDIOVASCULAR CONSEQUENCES OF CRF
QUESTION
Tell whether the following statement is true or false.
CRF leads to decreased cardiac output (CO).
ANSWER
TrueThe 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