TOPIC DISCUSSION: TTP/HUS

Old article, but nice review:
NEJM 2006;354:1927-1935

Key Points:

-90% mortality of TTP if untreated
-Pentad not needed for dxn, only MAHA and low plts along with appropriate clinical setting
-Childhood HUS with diarrheal prodrome (Shiga toxin/E.Coli O157:H7) treatment is only supportive care and antiobiotics should be withheld intially unless toxic/bacteremic since it may release more Shiga toxin and exacerbate the HUS
-ADAMTS13 deficiency (cleaving ulVWF) NOT seen in diarrheal prodrome HUS
-Neuro symtpoms more with TTP, renal more with HUS
-Distinguish TMA due to other disorders incl malignant HTN and autoimmune disorders
-LDH levels will be sky high often, schistos, polychromatophilic red cells, indirect bili, neg direct Coombs
-Acute flares may or may not have low levels of ADAMTS13, so cannot go by this, it only tells you risk of relapse
-PEX!!!! If delay, can use plasma infusion but not as effective. Steroids maybe
-Causes: Idiopathic (rare to have renal manifestations), pregnancy, autoimmune d/o, diarrheal prodrome (HUS), immune mediated and dose dependant drug toxicity, HST (TMA usually limited to kidney, unlikely to benefit from PEX)
-PEX works even if no severe ADAMTS13 deficiency