1/5 - The Mystery

The S...

Metadata

• Author: @tony_breu on Twitter
• Full Title: 1/5 - The Mystery
  The S...
• Category: #tweets
• URL: https://twitter.com/tony_breu/status/1573717588072448000

Highlights

• 1/5 - The Mystery
  The serum LDH in TTP is more than twice that seen in autoimmune hemolytic anemia (AIHA)
  🤔If the source of LDH in both conditions is lysed RBCs, shouldn't the values should be similar? (View Tweet)
• 2/5 - The Proof
  Let's start by confirming that the LDH in TTP is higher than what's seen in AIHA:
  ☞AIHA: ~700-800 IU/L (median)
  ☞TTP: ~1500 IU/L (mean)
  https://t.co/F7NKXTjPqv
  https://t.co/wCRCtDdgTi (View Tweet)
• 3/5 - The Answer
  💡The main source of LDH in TTP isn't lysed red blood cells.
  Recall that there are multiple LDH isoenzymes. RBCs contain LDH-1 and LDH-2, so these should be the main type elevated in TTP. They aren't.
  https://t.co/V4FcJZuziW (View Tweet)
• 4/5 - The Evidence
  One study looked at the LDH isoenzymes in patients with TTP.
  The percentage of LDH-1 and LDH-2 were not elevated above normal.
  🔑Instead, the percentage of LDH-5, the isoenzyme found in skeletal muscle and liver was elevated.
  https://t.co/DVruM501XK
  (View Tweet)
• 5/5 - The Implications
  ⚡️The authors of this study propose that the elevated LDH in TTP reflects tissue injury as a result of microvascular ischemia. (View Tweet)