Laboratory signs of VITT are significantly elevated D-dimers (up to five times the reference range), thrombocytopenia < 150,000/μl, reduced fibrinogen levels, positive PF4 antibodies in HIT-ELISA, and positive functional platelet activation tests (PAT) such as PIPA and serotonin release assay (SRA) test. Here, PF4 is linked to Thrombocytopenia.