TRUE about Heparin Indiced Thrombocytopenia (HIT) syndrome are all, EXCEPT:: (A) LMWH shouldn't be used for treatment, (B) It causes both aerial and venous thrombosis, (C) More common with fractionated heparin, (D) Occurs commonly in about a week of heparin therapy
Answer is C. Frequency of HIT after exposure to unfractionated heparin (UFH) is 1% to 5%, whereas the frequency of HIT associated with the used of low-molecular-weight heparin (LMWH) is only 1%. HIT occur due to the formation of antibodies against the complex of heparin bonded to platelet factor 4. Most patients develop HIT after exposure to heparin for 4 days but may occur suddenly in patients with recent exposure (< 100 days). It is paradoxically associated with increased risk of aerial and venous thrombosis. The 4 "T"s have been recommended to be used in a diagnostic algorithm for HIT: thrombocytopenia, timing of platelet count drop, thrombosis and other sequel such as localized skin reactions, and other cause of thrombocytopenia not evident.