Final answer:
The antibody test with the highest sensitivity for HIT is the Enzyme Immunoassay (ELISA). This test detects antibodies against heparin-bound platelet factor 4 in patient serum.
Step-by-step explanation:
The antibody test with the highest sensitivity for HIT (Heparin-Induced Thrombocytopenia) is the Enzyme Immunoassay (EIA) or Enzyme-Linked Immunosorbent Assay (ELISA). The ELISA test is based on the principle of antigen-antibody binding. In this test, patient serum is added to a plate coated with a specific antigen (in this case, heparin-bound platelet factor 4). If the patient has antibodies against heparin-bound platelet factor 4, the antibodies will bind to the antigen on the plate, resulting in a positive test result. The ELISA test is highly sensitive and can detect even low levels of antibodies, making it the preferred test for diagnosing HIT.