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H22 Hematology
Hemolytic Anemia
Toronto Notes 2019
Autoimmune Hemolytic Anemia
Table 14. Classification of AIHA
Antibody Allotype Agglutination Temperature
Direct Coombs Test (direct anti-globulin test)
Etiology
Blood Film Management
Warm (75-90% cases)
IgG
37oC
Positive for IgG ± complement
Idiopathic
Secondary to lymphoproliferative disorder (e.g. CLL, Hodgkin lymphoma)
Secondary to autoimmune disease (e.g. SLE) Drug-induced (e.g. penicillin, quinine, methyldopa)
Spherocytes
Treat underlying cause Corticosteroids Immunosuppression Splenectomy
Folic acid
Rituximab (2nd-line to steroids)
Cold
IgM
4-37oC
Positive for complement
Idiopathic
Secondary to infection
(e.g. mycoplasma pneumonia, EBV) Secondary to lymphoproliferative disorder (e.g. macroglobulinemia, CLL)
Agglutination
Treat underlying cause
Warm patient/avoid cold
Rituximab regiments (1st-line)
Plasma exchange (2nd-line for high IgM levels) Folic acid
Low dose alkylating agents (chlorambucil, cyclophosphamide) or interferon may be useful but less effective
Schistocyte
Vessel wall
Microangiopathic Hemolytic Anemia Thrombotic Microangiopathy
Definition
• hemolyticanemiaduetointravascularfragmentationofRBCs
Etiology
• seeThromboticThrombocytopenicPurpuraandHemolyticUremicSyndrome,H30 • seeDisseminatedIntravascularCoagulation,H32
• eclampsia,HELLPsyndrome,AFLP
• malignanthypertension
• vasculitis
• malfunctioningheartvalves
• metastaticcarcinoma
• drugs(calcineurininhibitors,quinine,simvastatin) • infections(severeCMVormeningococcus)
• catastrophicantiphospholipidantibodysyndrome
Investigations
• bloodfilm:evidenceofhemolysis,schistocytes • hemolyticworkup
• urine: hemosiderinuria, hemoglobinuria
Hereditary Spherocytosis
• mostcommontypeofhereditaryhemolyticanemia
• abnormalityinRBCmembraneproteins(e.g.spectrin)
■ spleen makes defective RBCs more spherocytotic (and more fragile) by membrane removal; also acts as site of RBC destruction
• autosomaldominantwithvariablepenetrance
Investigations
• bloodfilm(showsspherocytes),osmoticfragility(increased),molecularanalysisforspectringene
Treatment
• inseverecases,splenectomyandvaccinationagainstpneumococcus,meningococcus,andH.influenza type b (avoid in early childhood)
Thrombus
RBC
Figure 9. Schistocyte
© Kristina Neuman 2010