| A | B |
|---|
| Autoimmune Hemolytic Anemia (AIHA) | Acquired disorder characterized by premature erythrocyte destruction due to abnormal production of antibodies against the patient's own RBC antigens |
| Compensated Anemia | Rate of RBC production equals the rate of RBC destruction |
| Uncompensated Anemia | Rate of RBC destruction exceeds the rate of RBC production |
| Uncompensated anemia laboratory test results | Increased reticulocyte count;increased bilirubin and LDH; decreased Haptoglobin |
| Types of AIHA | 1. WARM- 70% - autoantibody optimally reactive 30-37C. 2. COLD - 18% - reactive 4-30 C. 3. DRUG INDUCED - 12%. |
| Characteristics of benign cold autoantibodies | 1) Reactive RT or below 2) Titer less than 64. 3) Common specificity anti-I,-IH. 3) DAT positive due to C3 usually 1+ or less. 4) Not clinically significant |
| Characteristics of Pathologic cold autoantibodies | 1) Reactive 30-37C. 2) Titer >1000. 3) Common specificity = anti-I. 4) DAT positive due to C3 2-4+. 5) Clinically signifiant 6) Secondary to viral infections i.e. M. pneumonia |
| Treatments for WAIHA | 1) Corticosteroids 2) IVIG 3) Splenectomy - when Steroid therapy fails 4) Immunosuppressive Drugs - last resort |
| WAIHA | 1) Caused by IgG autoantibody reactive at 37C. 2) RBC destruction is extravascular via the reticuloendothelial system. 3) DAT positive due to IgG or IgG and C3 |
| Cold Hemagglutin Disease (CHD) | 1) Occurs predominantly in older individuals. 2) Anti-I is the most common specificify. Anti-i is less common and rarely anti-Pr. 3) DAT positive due to anti-C3. 4) Treatment: stay in warm climate and transfusion support if needed |
| Paroxysmal Cold Hemoglobinuria (PCH) | 1) Least common 1% of all AIHA 2) Seen most commonly in children following viral infection 3) Biphasic hemolysin - IgG antibody attaches to RBC's at lower temps., binds complement, RBC's lyse as blood circulates to warmer core body temperatures. 3) Eluate negative 4) Antibody specificity is anti-P. 5) Donath Landsteiner Test is diagnostic |
| Drug Induced Immune Hemolytic Anemia (DIIHA) | Rare - 1/1,000,000 |
| Drug induced antibody production | 1) Antibody against the membrane bound drug (Drug-adsorption (Hapten) Mechanism) 2) Antibody against an RBC membrane component 3) Antibody against a drug/RBC component (Immune Complex Mechanism) |
| Drug Induced Causes of DAT | 1) Antibody production. 2) Non-immunologic protein adsorption (NIPA) onto the RBC membrane |
| Serologic Classification of Drug - Induced Antibodies | 1) Drug dependant - drug must be present in the test system. 2) Drug Independant - autoantibody induced by drug but invitro reactivity does not require presence of the drug |
| Drug dependant antibody characteristics | 1) Antibodies reactive only with drug-treated RBC's i.e. penicillin and some cephalosporins. 2) Antibodies reactive with untreated RBC's suspended in a solution of the drug i.e. quinine and ceftriaxone |
| Drug independant antibody characteristics | 1) Drug action alters T-cell function that results in failure to recognize "self" antigen as self but rather as foreign. 2) Drug examples: methyldopa, fludarabine 3) Serologically cannot distinguish drug independant autoantibodies from idiopathic warm autoantibodies |
