<unk> 
2 points: platelets > 50% fall AND nadir > 20k
1 points: patient 30-50% fall OR nadir 10-19k
Timing
2 points: clear onset 5-10 days OR platelet fall < 1 day with prior<unk>  exposure within 30 days
1 point: likely onset 5-10 days OR fall < 1 day with prior<unk>  exposure 30-100 days
Thrombosis
2 points: new thrombosis or skin necrosis at injection sites
1 point: suspected thrombosis or progressive/recurrent thrombosis
Likelihood of other causes
2 points: none apparent
1 point: possible
Scoring
≤ 3, low probability (≤5%)
4-5, intermediate prob (~15%)
≥ 6, high prob (~65%)
2 points: platelets > 50% fall AND nadir > 20k
1 points: patient 30-50% fall OR nadir 10-19k
2 points: clear onset 5-10 days OR platelet fall < 1 day with prior<unk>  exposure within 30 days
1 point: likely onset 5-10 days OR fall < 1 day with prior<unk>  exposure 30-100 days
2 points: new thrombosis or skin necrosis at injection sites
1 point: suspected thrombosis or progressive/recurrent thrombosis
2 points: none apparent
1 point: possible
≤ 3, low probability (≤5%)
4-5, intermediate prob (~15%)
≥ 6, high prob (~65%)
Heparin-Induced Thrombocytopenia 
Marrow infiltration 
Disseminated intravascular coagulation
Viral infections 
Liver disease induced coagulopathy
Marrow suppression 
Vitamin K deficiency
Congenital thrombocytopenia