Introduction: Heparin-induced thrombocytopenia (HIT) is a rare and serious immune-mediated complication of heparin therapy which is seldom reported in association with COVID-19. This report aims to present a case of accelerated HIT in a severe COVID-19 patient. Case report: A 63-year-old man presents with symptoms of COVID-19 for one week. He was conscious, ordinated, feverish, and had diffused chest crackles. Initial laboratory tests revealed elevated C-reactive protein of 87.66 mg/dL, elevated D-dimmer of 1258.9 ng/ml, elevated ferritin of 1020 ng/ml, and his platelet count was within the normal range. Polymerase chain reaction (PCR) confirmed the diagnosis of COVID-19. On the 9th day of admission, he developed a progressive worsening of dyspnea. His D-dimmer level significantly increased to 7020 ng/ml, and his interleukin-6 was 27.3 pg/ml. Hence, we started him on unfractionated heparin (UFH) for thromboprophylaxis. On the 12th day of hospitalization, the platelet count dropped from 258000 to 111000 cells/μL. He had a high probability of HIT (4Ts score = 6). As a result, we discontinued UFH and switched him to apixaban. His platelet count normalized (174000 cells/μL) within two weeks of ceasing UHF. Discussion: HIT results from the production of antibodies against platelet factor 4/heparin complexes. It is associated with a diminished platelet count within 5-10 days post heparin initiation. Because thrombocytopenia can occur in COVID-19 patients, HIT is seldom suspected. Conclusion: HIT should be considered a differential diagnosis in COVID-19 patients with thrombocytopenia.
