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Essentials of Pathophysiology. Chapter 26 Acute Renal Failure and Chronic Kidney Disease. Acute renal failure is not a reversible process. Chronic renal failure leads to hyperkalemia and the risk for cardiac arrhythmias.
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Essentials of Pathophysiology Chapter 26Acute Renal Failure and Chronic Kidney Disease
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 true/false F T T F F
__________ 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______________ Pre lecture Quiz • anemia • azotemia • Prerenal • hypertension • Uremia • Erythropoietin
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 creatininelevel ÷ current creatininelevel • 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 When Kidneys Fail
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 Acute Renal Failure
Which type of acute renal failure (ARF) would be most likely to accompany benign prostatic hypertrophy? • Prerenal • Postrenal • Intrinsic • Extrinsic Question
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. Answer
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. . A drug to prevent renal failure? Lancet 362,589-590.) Radiocontrast Agents Can Cause ARF
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
Scenario cont. Current Creatine / initial creatine 5.6/1.2= 4.7
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 Urine Containing Tubular Cell Casts
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? Scenario
Fewer nephrons are functioning • Remaining nephrons must filter more • Hyperperfusion • Hypertrophy Chronic Renal Failure
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 Development of CRF
Uremia = “Urine in the Blood” • Renal filtering function decreases • Altered fluid and electrolyte balance • Acidosis, hyperkalemia, salt wasting, hypertension • Wastes build up in blood • Increased creatinine and BUN • Toxic to CNS, RBCs, platelets • Kidney metabolic functions decrease • Decreased erythropoietin • Decreased Vitamin D activation Uremia
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. Vitamin D Activation
Which of the following renal disorders is characterized by increased BUN and creatinine levels? • ARF • CRF • Uremia • All of the above • b and c Question O || C / \ NH2NH2 UREA
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. Answer
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
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? Scenario (cont.)
Decreased blood viscosity + • Increased blood pressure + • Decreased oxygen supply Cardiovascular Consequences of CRF 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
Tell whether the following statement is true or false. CRF leads to decreased cardiac output (CO). Question
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. Answer