Clinical course, platelet counts, and anti-PF4/heparin antibody reactivity in the EIA and the SRA of 2 patients with prolonged heparin application despite clinical HIT. (A) A 74-year-old man developed thrombocytopenia, pulmonary embolism, and left femoral artery thrombosis on day 6 of postoperative UFH thromboprophylaxis. Despite increased (therapeutic) heparin dosing, the platelet count recovered from 59 × 109/L (nadir, day 10) to 155 × 109/L (day 13). On day 13, the positive SRA test result became available, and heparin was replaced by danaparoid. (B) An 81-year-old woman developed thrombocytopenia beginning on day 9 of postoperative UFH thromboprophylaxis after perforated sigmoid colon resection. Blood cultures on day 10 were positive for Enterococcus faecium, and the platelet count decline was considered to be related to “line sepsis.” Despite continued UFH thromboprophylaxis, the platelet count recovered from 79 × 109/L (nadir) to 157 × 109/L (day 23). On day 23, the positive SRA test result became available, and UFH was replaced by danaparoid.
