ÎLess common manifestations of HIT include:
> Venous limb gangrene (5%-10% of patients with HIT with DVT treated acutely with a vitamin K antagonist [VKA])
> Necrotizing skin lesions at heparin injection sites > Adrenal hemorrhagic necrosis (due to adrenal vein thrombosis) > Acute systemic reactions within 30 min of an IV heparin bolus injection (eg, fever/chills, tachycardia, hypertension, dyspnea, cardiopulmonary arrest)
> Disseminated intravascular coagulation (DIC) severe enough to deplete fibrinogen
ÎPetechiae or other signs of bleeding are rarely seen despite severe thrombocytopenia (but with a nadir rarely < 20 x 109
/L).
Table 1. Incidence of HIT (%) According to Patient Population and Type of Heparin Exposure
Heparin, prophylactic dose Heparin, therapeutic dose Heparin, flushes
Postoperative patients 1-5 1-5
LMWH, prophylactic or therapeutic dose Cardiac surgery patients
Patients with cancer
Heparin, prophylactic or therapeutic dose LMWH, prophylactic or therapeutic dose Intensive care patients Heparin, flushes Obstetrics patients
0.1-1 0.1-1 1-3
Medical 1
0.1-1 0.6 0.4
< 0.1 < 0.1
