HUS vs TTP
How to tell HUS and TTP apart when a board question makes them look alike.
Step 2 CK pairs are in open beta while clinical review finishes. Spot an issue? Tell us.
Recent bloody diarrhea with dominant acute kidney injury favors HUS.
Side by side
Child with recent bloody diarrhea, hemolytic anemia, thrombocytopenia, and acute kidney injury suggests typical HUS.
Adult with MAHA, thrombocytopenia, and prominent neurologic symptoms with minimal diarrhea history suggests TTP.
Shiga-toxin endothelial injury in renal microvasculature drives platelet consumption and hemolysis.
ADAMTS13 deficiency causes widespread platelet-rich microthrombi and organ ischemia.
HUS often shows creatinine elevation, schistocytes, platelets low to moderate, normal PT and aPTT, and stool assay positive for Shiga toxin in typical cases.
TTP usually has severe thrombocytopenia, schistocytes, normal PT and aPTT, very high LDH, and ADAMTS13 activity below 10 percent when available.
The trap
Giving empiric antibiotics and antimotility agents in suspected Shiga-toxin HUS can worsen toxin release and kidney injury. Supportive renal-focused care is preferred unless another infection is proven.
The repair move
Next best step: provide supportive care with careful IV fluids, monitor electrolytes and urine output, transfuse red cells if needed, and initiate dialysis for severe kidney injury in HUS. If adult TTP is suspected with neurologic findings and MAHA, start immediate plasma exchange and steroids without waiting for ADAMTS13 result.
Try a free question
CoreA 5-year-old has anemia, thrombocytopenia, schistocytes, and creatinine rise after bloody diarrhea. What is the next best step in management?
Show answer and explanation
Answer: A. Supportive care with renal monitoring and dialysis if needed. Typical HUS is managed primarily with supportive kidney-focused care.
Why the other choices are tempting
- B. Wrong. Plasma exchange is standard for TTP, not routine pediatric typical HUS.
- C. Wrong. Antimotility agents may worsen toxin-mediated disease.
- D. Wrong. Anticoagulation is not standard HUS therapy.
- E. Wrong. Untreated HUS can progress to severe renal complications.
Flashcards
Tap a card to flip it.
Which historical clue is most useful for diagnosing typical HUS?
Recent bloody diarrheal illness, often from Shiga-toxin infection.
Which organ involvement tends to dominate in HUS compared with TTP?
Acute kidney injury is usually more prominent in HUS.
Quick answers
What is the fastest way to tell HUS from TTP?
Recent bloody diarrhea with dominant acute kidney injury favors HUS.
What is the key clue for HUS?
Child with recent bloody diarrhea, hemolytic anemia, thrombocytopenia, and acute kidney injury suggests typical HUS.
What is the key clue for TTP?
Adult with MAHA, thrombocytopenia, and prominent neurologic symptoms with minimal diarrhea history suggests TTP.
What is the common trap with HUS vs TTP?
Giving empiric antibiotics and antimotility agents in suspected Shiga-toxin HUS can worsen toxin release and kidney injury. Supportive renal-focused care is preferred unless another infection is proven.