View source for Autoimmune hemolytic anemia

==Background==
*Autoimmune hemolytic anemia (AIHA) = generation of auto-antibodies towards red blood cell membrane antigens, leady to hemolysis. 
*Can be primary (idopathic) or due to another disease process (e.g. malignancy, autoimmune disease, infection)

==="Warm" Autoimmune Hemolytic Anemia===
''Autoantibodies agglutinate to RBCs at higher temperatures''
*IgG mediated, usually pan-reactive to patient's and transfused RBCs
*Extravascular (i.e. in spleen) hemolysis→ unconjugated > conjugated hyperbilirubinemia
*Haptoglobin low, LDH may be normal
*Causes:
**[[Lymphoma]], especially Non-Hodgkin's lymphoma
**[[Leukemia]], particularly [[chronic lymphocytic leukemia]]
**Collagen vascular diseases (E.g. [[Systemic Lupus Erythematosus]], [[Rheumatoid arthritis]], [[Giant cell arteritis]]
**Viral-induced or [[HIV]]-associated
**Medications: methyldopa, quinidine, [[penicillin]]

==="Cold" Autoimmune Hemolytic Anemia===
''Autoantibodies agglutinate at lower temperatures''
*IgM mediated
*Intravascular hemolysis→ high LDH, low haptoglobin, hemoglobinuria
*Causes:
**Infection, most commonly [[Mycoplasma pneumoniae]] and [[mononucleosis]], also [[varicella]], [[listeria]], [[influenza]]
**[[Multiple myeloma]] and other plasmacytomas
**Idiopathic

==Clinical Features==
*Signs and symptoms of [[anemia]] (fatigue, pallor, palpitations, etc.)
*[[Jaundice]] and scleral icterus
*Signs/symptoms of underlying disease process
*Cold-type:
**Acrocyanosis, Raynaud's, vascular occlusion with peripehral tissue ischemia

==Differential Diagnosis==
{{Anemia DDX}}

==Evaluation==
*CBC, LFTs, LDH, haptoglobin 
*Direct Coombs test - blood sample is removed of plasma and incubated with anti-human immunoglobulin (aka "Coombs reagent"). This detects if autoantibodies are attached to RBCs or compliment. If the RBCs are coated with IgG (positive direct Coombs test), this suggests the diagnosis of "warm AIHA. If the RBCs are coated with only compliment, this suggests the diagnosis of "cold" AIHA

==Management==
===Warm AIHA===
*Oral [[prednisone]] 1-1.5mg/kg/day for 1-3 weeks with taper after hemoglobin stable
**may need several months of low dose [[prednisone]] to remain in remission
*[[Splenectomy]] and/or cytotoxic drugs for for steroid-refractory disease
*[[Plasmapheresis]] as temporizing measure for severe disease
*Transfuse [[pRBCs]] only if truly life-threatening anemia, least incompatible units possible

===Cold AIHA===
*No treatment for mild disease
*Immunosuppressive or cytotoxic medications can be considered
*[[Plasmapheresis]] for severe disease

==Disposition==

==See Also==
*[[Paroxysmal nocturnal hemoglobinuria]] (PNH)
*[[Systemic lupus erythematosus]]
*[[Rheumatoid arthritis]]
*[[Scleroderma]]

==References==
<references/>
[[Category:Heme/Onc]]