Acute drug-induced immune thrombocytopenia - A work of articaine.

BACKGROUND: Drug-induced immune thrombocytopenia (DITP) is a rare, but serious complication to a wide range of medications. Upon suspicion, one should do a thorough clinical evaluation following proposed diagnostic criteria and seek laboratory confirmation. If confirmed, it is important to ensure avoidance of the drug in the future. STUDY DESIGN AND METHODS: Herein, we describe a young adult male who experienced two bouts of severe thrombocytopenia following dental treatment. The thrombocytopenia was acknowledged due to unexpected hemorrhaging during the procedures. On both occasions, he was exposed to four different drugs, none commonly associated with DITP. After the second episode of severe procedural-related thrombocytopenia, an investigation into the cause was initiated. We describe the clinical approach to elucidate which of the four implicated drugs was responsible for thrombocytopenia and the laboratory work-up done to confirm that the reaction was antibody-mediated and identify the antibody's drug: glycoprotein specificity. An alternative drug was tested both in vivo and in vitro, to identify an option for future procedures. RESULTS: Sequential exposure revealed the local anesthetic substance articaine to induce thrombocytopenia. Laboratory work-up confirmed drug-dependent antibodies (DDAbs) with specificity for the glycoprotein Ib/IX complex, swiftly identified by a bead-based Luminex assay. Further investigations by monoclonal antibody immobilization of platelet antigens assay (MAIPA) revealed a probable GPIb binding site. An alternative local anesthetic, lidocaine, was deemed safe for future procedures. CONCLUSION: Articaine can induce rapid-onset, severe immune-mediated thrombocytopenia causing bleeding complications. A modified bead-based Luminex platelet antigen assay proved a useful addition in the DITP-investigation.

Anti-PF4/polyanion antibodies in COVID-19 patients are associated with disease severity and pulmonary pathology.

Thromboembolic events are frequent and associated with poor outcome in severe COVID-19 disease. Anti-PF4/polyanion antibodies are related to heparin-induced thrombocytopenia (HIT) and thrombus formation, but data on these antibodies in unselected COVID-19 populations are scarce. We assessed the presence of anti-PF4/polyanion antibodies in prospectively collected serum from an unselected cohort of hospitalized COVID-19 patients and evaluated if elevated levels could give prognostic information on ICU admission and respiratory failure (RF), were associated with markers of inflammation, endothelial activation, platelet activation, coagulation and fibrosis and were associated with long-term pulmonary CT changes. Five out of 65 patients had anti-PF4/polyanion reactivity with OD ≥0.200. These patients had more severe disease as reflected by ICU admission without any evidence of HIT. They also had signs of enhanced inflammation and fibrinogenesis as reflected by elevated ferritin and osteopontin, respectively, during the first 10 days of hospitalization. Increased ferritin and osteopontin persisted in these patients at 3 months follow-up, concomitant with pulmonary CT pathology. Our finding shows that the presence of anti-PF4/polyanion antibodies in unselected hospitalized COVID-19 patients was not related to HIT, but was associated with disease severity, inflammation, and pulmonary pathology after 3 months.

Thrombosis and thrombocytopenia after HPV vaccination.

BACKGROUND: Vaccine-induced immune thrombotic thrombocytopenia (VITT) has so far only been reported after adenovirus vector severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines. OBJECTIVE: We report findings in a 25-year-old woman who presented with thrombocytopenia, venous thrombosis, elevated D-dimer levels, and high levels of platelet-activating antibodies to platelet factor 4-polyanion complexes 10 days after Gardasil 9 vaccination for human papillomavirus (HPV). The patient exhibited clinical and laboratory features in line with the recently defined VITT syndrome, described after adenoviral vector vaccination to prevent coronavirus disease 2019. CONCLUSION: We report a case of VITT following HPV vaccination. This should raise awareness of the possibility of VITT also occurring after other vaccines, not exclusively adenoviral vector-based SARS-CoV-2 vaccines.