title: A case of pseudothrombocytopenia after infusion of abciximab in vivo and anticoagulant-independent platelet clumping after rechallenge with abciximab in vitro.
abstract: A 45-year old man was treated for unstable angina pectoris with percutaneous transluminal angioplasty and stenting of his left anterior descending coronary artery. The procedure was followed by infusion of abciximab. The patient's automated platelet count in an EDTA-anticoagulated blood sample at admission to the hospital was normal, but dropped to 5 x 10(9)/l three hours after the procedure. The infusion of abciximab was stopped and the patient received platelet transfusions although there were no signs of bleeding. Two days later his platelet count was still low (37 x 10(9)/l) in an EDTA-anticoagulated blood sample, but normal (193 x 10(9)/l) in a heparin-anticoagulated sample. Platelet clumps were present only in the sample anticoagulated with EDTA, and pseudothrombocytopenia was diagnosed. The patient's recovery was uneventful. At follow-up visits four months and one year after discharge from hospital, the patient's blood samples were anticoagulated with three different anticoagulants: EDTA, citrate and heparin. The platelet count was normal in all three samples but after mixing with abciximab in vitro it dropped profoundly due to platelet clumping, regardless of the choice of the anticoagulant. Our report raises two points: (a) one needs to consider the possibility of pseudothrombocytopenia in a patient with a low automated platelet count after infusion of abciximab but without signs of bleeding, and (b) the in vitro results suggest that our patient who had initially responded to abciximab with pseudothrombocytopenia could develop true thrombocytopenia after repeated exposure.
authors.affiliation: Department of Angiology, University Medical Centre Ljubljana, Slovenia.
authors.forename: M
authors.initials: M
authors.lastname: Kozak
authors.forename: T
authors.initials: T
authors.lastname: Dovc
authors.forename: P
authors.initials: P
authors.lastname: Rozman
authors.forename: A
authors.initials: A
authors.lastname: Blinc
mesh_terms: D000077284:Abciximab; D000789:Angina, Unstable / Q000628:therapy; D015906:Angioplasty, Balloon, Coronary; D000911:Antibodies, Monoclonal / Q000009:adverse effects* / Q000494:pharmacology; D000925:Anticoagulants / Q000009:adverse effects* / Q000494:pharmacology; D001780:Blood Coagulation Tests; D003937:Diagnosis, Differential; D004492:Edetic Acid / Q000494:pharmacology; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000009:adverse effects* / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000009:adverse effects* / Q000494:pharmacology; D010976:Platelet Count; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors*; D013921:Thrombocytopenia / Q000097:blood / Q000139:chemically induced* / Q000175:diagnosis
chemical_list: D000911:Antibodies, Monoclonal; D000925:Anticoagulants; D007140:Immunoglobulin Fab Fragments; D010975:Platelet Aggregation Inhibitors; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D004492:Edetic Acid; D000077284:Abciximab