Autoimmune hemolytic anemia (AIHA)

The presence of autoantibodies that bind to the patient’s own erythrocytes leading to premature red cell destruction. AIHA may develop gradually, with concomitant physiological compensation, or may have a fulminant onset with profound, life-threatening anemia especially with warm abs and in children with reticulocytopenia that reported to occur in 39% of children. AIHA = Hemolytic anemia + frequent mismatch ±Positive direct coombs test.

Classification • 1ry (No evidence of an underlying systemic illness) 1. Warm-reactive AIHA 2. Paroxysmal cold hemoglobinuria 3. Cold agglutinin disease • 2ry 1. Autoimmune disease (Systemic lupus, Rheumatoid arthritis, Scleroderma, Dermatomyositis, Ulcerative colitis, Giant cell hepatitis ……etc) 2. Medications (Quinine, Quinidine, Phenacetin, P-aminosalicylic acid, Penicillins, Cephalosporins, Tetracycline, Sulphonamides…….etc) 3. Malignancy (Leukemias and Lymphomas) 4. Infections (EBV, CMV, HIV, HSV, Hepatitis, Varicella, Measles, Mycoplasma pneumonia) 5. Immune deficiency (ALPS , SCID, CVID
-Evidence of hemolytic anemia (low Hb and reticulocytosis, increased total and indirect bilirubin, elevated LDH) -Serological evidence of anti-erythrocyte antibodies, detectable by the direct coombs test. -Frequent mismatch is pathognomonic even with negative direct coombs test.
*Do not forget to check for Kidney functions and blood pressure to exclude acute renal shutdown with severe hemolysis or to exclude hemolytic uremic disease
Severe cases may need very strong transfusion support and represent a clinical emergency. 1. Life saving measures if decompensated (see management in isolated anemia) 2. Arrange for packed RBCs TRANSFUSION see management in isolated anemia) Try to get compatible blood 1. Try a single high dose steroids (Methyl prednisolone at a dose of 30 mg/kg/dose) and recheck for compatibility after 15 to 30 minuts.
. O-ve (Least incompatible) If failed Give O-ve (Least incompatible) after consenting the parents. Better to be given in an ICU or under close monitoring of the patient. Blood should be given under cover of high dose steroids (Methyl prednisolone at a dose of 30 mg/kg/dose)
3. Full history taking and thorough clinical examination 4. Laboratory assessment: • CBC with differential count. • Rtx : Usually ↑ but may be ↓ as they are destroyed by the Abs • Blood film : Spherocytes , Polychromasia , Normoblasts • DAT (Direct antiglobulin test or coomb’s test): +ve (May be –ve in <5%) • TSB (Indirect hyperbilirubinemia) , LDH and AST ↑ • ESR ↑: Malignancy and autoimmune disease as SLE and RA • Virology screening : EBV and CMV IgG and IgM NB: Patients <1 year and those with history of repeated infections or a positive family history of immune deficiency should do Igs and CDs to rule out immune deficiency
Consult a hematologist to start Specific therapy: 1st line: o Patients with rapid hemolysis and very severe anemia, or complex cases such as Evans syndrome, start intravenous methylprednisolone at 30mg/kg/d mg/ for 3 days, then taper according to response (i.e. stable Hb, decreasing Retix) at 2.5 or 5m/kg every 3 to 5 days. o Intravenous immunoglobulins (IVIG) at dose 2- 4 gm/kg total dose divided over 2 days may be used alone or in combination with steroids. o Plasma exchange is to be considered if the anemia could not be stabilized with other therapies

• Frequent mismatch is considered pathognomonic if patients has no H/O previous transfusions. • Direct coombs test (DAT) may be false-negative due to IgA autoantibodies (that are not detectable by most routine reagents), low-affinity IgG, or RBCbound IgG below the threshold of the test. Approximately 10% of AIHA remain DAT negative, and the diagnosis is made after exclusion of other causes of hemolysis and on the basis of the clinical response to therapy.