46. Acute tubular necrosis Flashcards Preview

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Flashcards in 46. Acute tubular necrosis Deck (23):
1

Acute kidney injury is AKA

acute renal failure

2

MCC caof acute kidney injury in hospitalized patients

Acute tubular necrosis

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prognosis

can be fata, esp during initial oliguric phase

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FENa

more than 2%

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key finding

granular ( muddy brown ( casts

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stages

1. inciting event
2. maintenance phase - oliguric
3. Recovery phase - oliguric

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duration of maintenace phase

1-3 weeks

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maintenance phase risk for

1. hypokalemia
2. metabolic acidosis
3. uremia

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Recovery phase - findings

BUN and creatinine fall

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recovery phae - risk for

hypokalemia

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Acute tubular necrosis can be caused by ... (groups )

1. ischemic factors
2. nephrotoxic factors

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ischemic factors - mechanism

2ry to low RBF ( eg hypotension , shock , sepsis , hemorrhage, HF) (often preceded by renala azotemia ) --> reuslts in death of tubular cells that may slough into tubular lumen

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areas that are highly susceptible to ischemic injury

1. PCT
2. Thick ascending limb

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Nephrotoxic factors - mechanism

2ry to injury resulting from toxic substance ( eg. aminoglycosides radiocontrasts agents. lead, cisplatin ), crush injury ( myoglobinuria), hemoglobinuria

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areas tha highly sucseptible to nephrotoxic injury

PCT

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area that are highlu sucseptible to ischemic injury vs nephrotoxic injury

ischemic injury --> PCT , thick ascending limb
nephrotoxic injury --> PCT

17

• What is the most common cause of acute kidney injury in hospitalized patients? What happens if it is left untreated?

Acute tubular necrosis—self-reversing in some cases but can be fatal if left untreated

18

• A septic patient is hypotensive. Urinalysis shows muddy brown casts and the patient is oliguric. What is the cause of this renal pathology?

Decreased renal blood flow, causing ischemic damage to tubular cells (this is acute tubular necrosis)

19

• What are the two broad categories of acute tubular necrosis?

Ischemia resulting from decreased blood flow and direct nephrotoxicity

20

• A man with acute renal failure has hematuria, proteinuria, and muddy brown urine casts. Death will most likely occur in which disease stage?

The initial oliguric phase (maintenance, lasting 1–3 weeks) if dialysis is not started (the patient has acute tubular necrosis)

21

• What are the three stages of acute tubular necrosis?

Inciting event, maintenance (oliguric, hyperkalemia risk), and recovery (polyuric, BUN and serum creatinine fall, hypokalemia risk)

22

• An addict overdoses and begins seizing; hematuria develops and his creatinine rises sharply. What type of casts do you expect on urinalysis?

Granular "muddy brown" casts (the patient has acute tubular necrosis caused by myoglobinuria that resulted from his seizure)

23

• An normotensive ICU patient receives aminoglycosides and begins to decompensate. These findings are noted on renal biopsy. High or low FENa?

This is most likely nephrotoxic injury caused by the aminoglycoside antibiotics, resulting in acute tubular necrosis, so FENa is high

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