Cold Blood
A short Tweetorial
3 confusing diseases
1. Cold agglutinin disease
2. Cryoglobulinemia
3. Paroxysmal cold hemoglobinuria
2 of these disease are seen often on both the heme consult service and boards.
Cold Agglutinin Disease
Hemolytic anemia precipitated by cold
Monoclonal IgM binds RBCs (I antigen), agglutination, and fixes complement in cold->hemolysis
DAT+ for C3 and - for IgG
Associated with IgM gammopathies/LPL
Polyclonal form after Mycoplasma infection
Rx = Rituximab
Cryoglobulinemia = precipitate at cold temp
I:
MPGN, palpable purpura
Monoclonal IgG/IgM
LPL, MGUS, myeloma, CLL
II:
Meltzer's triad = palpable purpura, arthralgias, weakness
Mononeuritis multiplex
Monoclonal IgM + polyclonal IgG
HCV, HIV
III:
Polyclonal IgM+IgG
Autoimmune dz
Paroxysmal cold hemoglobinuria
Cold polyclonal IgG (Donath Landsteiner Ab)
Unlike cold-reacting IgM, no RBC agglutination
But able to fix 1st 2 components of complement in cold
Antibody dissociates at warmer temps
Complement cascade completed on rewarming and hemolysis occurs
Paroxysmal cold hemoglobinuria
Polyclonal IgG specific to P antigen of RBC
DAT positive (anti-C3)
Associated with upper respiratory infections
Historically associated with secondary or tertiary syphilis
Clinical manifestations: Dark urine after exposure to cold
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