5.5 Path: Acute Renal Failure and ATN

Question 1

Most common cause of ARF?

Answer 1

ATN: Acute tubular necrosis

Question 2

What is Acute Tubular necrosis?

Answer 2

Severe impairment of tubular epithelial cells , reversible

Question 3

What are the 2 types of ATN

Answer 3

Ischemic vs. Toxic

Question 4

Ischemic ATN? Causes? Patho phys? Gross? Where? EM?

Answer 4

Due to hypotension, decreased perfusion Causes: MI, CHF, hemorrhage, prolonged diarrhea, shock Pathophys: Sloughing and necrosis of the epithelium cells–>Cast form–>obstruction and increased interluminal pressure–>Decrease GFR–>Afferent arteriole constriction Gross: Pale cortex, congested medulla. PCT effected, flat appearing on EM, because no brush border

Question 5

Toxic ATN

Answer 5

Caused by chemical damage to tubular epithelial cells at PCT Causes: Abx, (aminoglycosides), contrast, organic ions, Rhabdomyolysis, HGB, massive hemolytic anemias, heavy metals

Question 6

Ethylene Glycol poisoning and ATN

Answer 6

Antifreeze ingestion–>Metabolized to oxalic acids–>Oxalic crystals form–> CNS sx, and cardio resp sx, and renal

Question 7

Recovery phase of ATN

Answer 7

Regeneration of tubular epithelial cells, cell growth and nuclei enlarged Increased urination and increase GFR, decrease CR serum

Question 8

Clinical findings with ATN; UA

Answer 8

Decreased urination, decrease GFR UA: Granular, brown casts

Question 9

Uremia signs

Answer 9

Metabolic acidosis, hyperkalemia, azotemia, fluid retention

Question 10

Renal thrombotic Microangiopathies

Answer 10

Systemic disease–>Damage to Endothelium–>Plasma enter intima walls of arterioles–>Subendothelial zone of glomerular cap–>Narrowing and ischemia of vessel–>Promote thrombosis–>Misshapen and distorted RBC–>Schistocytes with thrombopenia

Question 11

HUS, Hemolytic Uremic Sydrome

Answer 11

Seen in Kids. E.Coli, diarrhea, Triad: Microangiopathic hemolytic anemia Thrombocytopenia, ARF Causes: E.Coli most common; Viral, AIDS, Malignancies, Drugs

Question 12

Patho of HUS

Answer 12

Toxins released by bacteria–>Epithelial and endothelial damage–>imbalance of platelet aggregation factors Endothelial damage–>cascade of evens–>Microvascular lesions iwth microthrombi arterioles and capillaries

Question 13

Bood smear findsings of HUS

Answer 13

Helmut, Schistcytes, and Helmut cells due to microangiopathic hemolysis

Question 14

BUN/Cr of HUS

Answer 14

elevated due to ARF

Question 15

Clinical findings for HUS (7)

Answer 15

Diarrhea diarrhea watery and bloody pallor due to anemia petichaie and purpura on skin due to thrombocytopenia Oliguria, edema, HTN, CHR NEuro sx GI tract–>Intussusseption or perf with GI

Question 16

HUS tx

Answer 16

Plasmapharesis until remission Nephrologist Diarrhea control Fluids

Question 17

TTP

Answer 17

Thrombotic thrombocytopenic purpura Systemic microvascular thrombosis, thrombocytopenia, purpura, fever, changes in mental status. Renal involvement unlikely

Question 18

Other causes of Acute renal injury

Answer 18

acute post strep GMN Rapidly progressive crescentic GMN