Flashcards in Acute Renal Failure Deck (36):
What is acute renal failure?
Acute, severe decrease in renal failure. (Develops within days)
What is the hallmark sign of Acute renal failure?
Azotemia often with Oliguria.
What are the the different forms of Azotemia?
What are the causes of Prerenal Azotemia / Acute renal failure?
Results from decreased bloodflow to the kidneys (hypoperfusion).
What are the consequences of renal hypoperfusion?
How is this prerenal Azotemia induced Acute renal failure seen?
1.Reabsorption of BUN and Creatinine ensues (serum BUN:Cr ratio > 15)
2.Tubular function remains intact (urine osmolality >500 mOsm/kg
What is postrenal Azotemia / Acute renal failure?
Due to obstruction of the urinary tract downstream of the kidney e.g ureters
What are the results of Postrenal Azotemia / Acute renal failure
What is the presentation in the EARLY STAGES of Postrenal acute kidney failure?
1.Increased tubular pressure forces BUN into the blood Serum BUN:Creatinine >15
2.Urine osmolality of >500 mOsm
What is the presentation in the LATER STAGES of Postrenal acute kidney failure?
1.Tubular damage ensues resulting in decreased reabsorption of BUN (serum BUN:Creatinine ratio 2%
3.Inability to concentrate urine so urine osmolality <500 mOsm
What is the most common cause of acute renal failure (Intrarenal Azotemia)?
Acute Tubular Necrosis
What is acute Tubular Necrosis?
Injury and Necrosis of Tubular epithelial cells
What are the presentations of ACUTE TUBULAR NECROSIS?
1.Oliguria with Brown Granular casts
2.Elevated BUN and Creatinine
3.Hyperkalemia (due to increased renal excretion) with metabolic acidosis due to inability to excrete organic acids as well (increased anion gap)
What are the etiologies of Actute Tubular Necrosis?
1.Injury and Necrosis of tubular epithelial cells
2.Necrotic cells plug tubules decreasing GFR
3.Dysfunctional tubular epithelium results in decreased reabsorption of BUN (serum BUN:Creatinine ratio 2%)
-Urine osmolality <500 mOsm
What is seen in the Urine of patients with acute tubular necrosis?
Brown granular cast
What are the 2 main possible causes of Acute tubular necrosis?
How does Ischemia cause acute tubular necrosis
Poor perfusion causes cell death in tubules
-often preceded by prerenal azotemia
What portions of the kidney are most vulnerable to ischemic damage?
2.Medullary segment of the thick ascending limb
What part of the nephron is most susceptible to damage in Nephrotoxic acute tubular necrosis?
What is the most common cause of Nephrotoxic Acute Tubular Necrosis?
What are the other causes of Nephrotoxic Acute Tubular Necrosis?
1.Heavy Metals (lead)
2.Myoglobinuria (from crush injury to muscle)
3.Ethylene Glycol (Oxalate crystals in urine)
4.Radio contrast dye
5.Urate (tumor lysis syndrome)
What therapies are used prior to initiation of chemo to reduce risk of Acute Tubular Necrosis?
Hydration and allopurinol
Is ATN reversible?
Often but requires supportive dialysis since electrolyte imbalance can be fatal.
What is acute interstitial Nephritis?
Drug-induced hypersensitivity involving the interstitium and tubules that results in acute renal failure (intrarenal Azotemia)
What are some of the mail causes of acute interstitial nephritis?
NSAIDs, penicillin, and Diuretics
What is the presentation of Acute Interstitial Nephritis?
3.Rash days to weeks after starting a drug
-Eosinophils may be in the urine
What may Acute interstitial Nephritis progress to?
Renal papillary Necrosis
What is Renal Papillary Necrosis?
Necrosis of the renal papillae
How does Renal Papillary necrosis present?
What are some of the causes of Renal Papillary Necrosis?
1.Chronic Analgesic Abuse (phenacetin or asprin)
3.Sickle cell trait or disease
4.Severe acute Pyelonephritis
What The most common cause of acute kidney injury?
What is the most common cause of ischemia?
Shock especially septic shock.
Does renal ischemia usually affect the Glomeruli?
What kind of necrosis affects the Glomeruli?
Cortical Necrosis (Irreversible)
What is the most common type of renal carcinoma?
Clear cell carcinoma.