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Flashcards in Thrombotic microangiopathies Deck (20):
1

What are thrombotic microangiopathies?

A group of diseases characterized by widespread microvascular thrombosis.

2

How do patients present clinically?

1.microangiopathic hemolytic anemia
2.Thrombocytopenia
3.renal failure

3

What are the possible causes of Thrombotic microangiopathies?

1.HUS (primarily in children
2.TTP (primarily in adults)

4

What is the etiology of Thrombotic microangiopathies?

Typically there are fibrin thrombi in the microvasculature with Glomeruli being affected if enough vessels are affected it can lead to cortical renal stenosis.




5

What is the fundamental pathogenesis of thrombotic microangiopathies?

Loss of thromboresistance by endothelial cells. (loss of NO and prostacyclin to keep blood flowing freely and liquid) As a result platelets are activated and they aggregate and adhere to vessel walls.

6

Where would you expect to see HUS?

In a child post infection from SHIGA toxin from diarrheal E. coli H7:0157

7

What is the cause of TTP?

von Willebrand factor multimers from ADAMTS 13 deficiency

8

Where does fibrin deposit if there is endothelial damage in the thrombotic microangiopathies?


1.Lumen
2.Subintima
3.Media

9

In severe cases where there is involvement of larger blood vessels what occurs?

Concentric thickening resembling an onion skin appearance on biopsy

10

What chemical agents/therapeutic agents can also cause endothelial damage?

1.Radiation
2.Chem with Cisplatin
3.Gemcitabine or bleomycin
4.Cyclosporin

11

Why shouldn't Calcineurin inhibitors such as Tacrolimus be used for immunosuppression in kidney transplant?



Because they are nephrotoxic

12

What is the major difference between TMA and DIC?

In PT and PTT are normal in TMA but prolonged in DIC


13

What subset of patients does HUS primarily affect?

Small children under 5

14

What is the pathogenesis of thrombosis in HUS?

Endothelial cells bind shiga toxin resulting in endothelial damage with increased production of endothelin and decreased production of NO





15

How do cell die in HUS?

Internalization of Shiga-toxin

16

What is the typical presentation of TMA from HUS?

1.Sudden onset
-irritability
-lethargy
-weakness
-pallor
-Oliguria 5-10 days following gastroenteritis manifested by fever, abdominal pain vomitin and diarrhea (often bloody)

17

What would blood testing in HUS reveal?

1.Schistocytes
2.Low platelet count

18

What treatments are required in HUS?

1.Blood transfusion
2.Renal dialysis
3.Eculizumab (monoclonal antibody to C5 that blocks complement activation

19

What are the associations with TTP?

1.Neurologic dysfunction
2.Renal dysfunction
3.Fever

20

What should one do if TTP is suspected (older adult subacute onset of malaise fatigue petechiae pallor confusion nausea)

Plasmapheresis