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Questions and Answers
What is the hallmark of acute renal failure?
What is the hallmark of acute renal failure?
What indicates prerenal azotemia?
What indicates prerenal azotemia?
What is a common feature associated with postrenal azotemia during the early stage of obstruction?
What is a common feature associated with postrenal azotemia during the early stage of obstruction?
Which of the following is typically associated with acute tubular necrosis?
Which of the following is typically associated with acute tubular necrosis?
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What primarily contributes to ischemic acute tubular necrosis?
What primarily contributes to ischemic acute tubular necrosis?
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Which of the following is a nephrotoxic cause of acute tubular necrosis?
Which of the following is a nephrotoxic cause of acute tubular necrosis?
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What happens to tubular function with long-standing postrenal azotemia?
What happens to tubular function with long-standing postrenal azotemia?
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What is the effect of hydration and allopurinol prior to chemotherapy?
What is the effect of hydration and allopurinol prior to chemotherapy?
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Study Notes
Acute Renal Failure (ARF)
- ARF is an acute, severe decline in kidney function, developing within days.
- A key sign is azotemia, characterized by elevated BUN and creatinine levels, often accompanied by oliguria (low urine output).
Prerenal Azotemia
- Results from reduced blood flow to the kidneys, such as in heart failure.
- This reduced blood flow leads to decreased glomerular filtration rate (GFR), azotemia, and oliguria.
- Urine sodium excretion is low (FENa < 1%), and urine osmolality is high (>500 mOsm/kg).
Postrenal Azotemia
- Caused by obstruction of the urinary tract, such as a blockage in the ureters.
- Obstruction leads to reduced GFR, azotemia, and oliguria.
- Early in the obstruction, elevated BUN:Cr ratios (>15) may be seen.
- With prolonged obstruction, BUN:Cr ratios might decrease (<15), sodium reabsorption decreases (FENa > 2%), and urine concentration ability is impaired (urine osmolality < 500 mOsm/kg).
Acute Tubular Necrosis (ATN)
- ATN is a common cause of intrarenal azotemia, often due to tubular epithelial cell injury/necrosis.
- Necrosis results in blockage of tubules, reducing GFR.
- Causes can be ischemic (reduced blood supply) or nephrotoxic (toxins).
- Common nephrotoxins include aminoglycosides, heavy metals, myoglobin, ethylene glycol, radiocontrast, and urates.
- Urine often contains brown, granular casts.
Clinical Features of ARF
- Oliguria (low urine output) and brown granular casts are common findings.
- Elevated BUN and creatinine are observed.
- Hyperkalemia (high potassium levels), and metabolic acidosis are possible, requiring supportive dialysis.
- Oliguria can persist 2- 3 weeks before recovery, as tubular cells regenerate.
Acute Interstitial Nephritis (AIN)
- AIN is a drug-induced hypersensitivity reaction impacting the kidney interstitium and tubules, often causing acute renal failure.
- Common causes are NSAIDs, penicillin, and diuretics.
- Symptoms include oliguria, fever, and rash, days to weeks after starting the drug.
- Eosinophils may be noted in urine.
- Resolved with drug cessation.
Renal Papillary Necrosis
- Renal papillary necrosis involves necrosis of renal papillae, characterized by gross hematuria and flank pain.
- Causes can include chronic analgesic abuse (e.g., phenacetin or aspirin use), diabetes mellitus, sickle cell trait/disease, and severe pyelonephritis.
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Description
This quiz covers the key aspects of Acute Renal Failure (ARF), including its types such as prerenal and postrenal azotemia. It explores the signs, causes, and implications of ARF, along with the significance of parameters like BUN, creatinine levels, and urine output. Test your understanding of this critical condition and its underlying pathology.
