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Heparin-Induced Thrombocytopenia

 Syn. Heparin induced thrombocytopenia , HIT

Signs & Symptoms

 Recent heparin exposure #criteria
Note: High risk in range 4-15 days and the highest is in past 5-10 days. Unfractionated heparin>low molecular weight heparin (=LMWH)>fondaparinux
Ref: Uptodate [ Clinical presentation and diagnosis of heparin-induced thrombocytopenia] Epocrates [ https://online.epocrates.com/diseases/1202/Heparin-induced-thrombocytopenia]
Unfractionated heparin #criteria
Note: High risk in range 4-15 days and the highest is in past 5-10 days. Unfractionated heparin>low molecular weight heparin (=LMWH)>fondaparinux
Ref: Uptodate [ Clinical presentation and diagnosis of heparin-induced thrombocytopenia] Epocrates [ https://online.epocrates.com/diseases/1202/Heparin-induced-thrombocytopenia]
Low molecular weight heparin #criteria
Note: High risk in range 4-15 days and the highest is in past 5-10 days. Unfractionated heparin>low molecular weight heparin (=LMWH)>fondaparinux
Ref: Uptodate [ Clinical presentation and diagnosis of heparin-induced thrombocytopenia] Epocrates [ https://online.epocrates.com/diseases/1202/Heparin-induced-thrombocytopenia]
History of HIT
Ref: Uptodate [ Clinical presentation and diagnosis of heparin-induced thrombocytopenia] Epocrates [ https://online.epocrates.com/diseases/1202/Heparin-induced-thrombocytopenia]

Physical Examination

 Thrombocytopenia recovers spontaneously (negative symptom)
Ref: Epocrates [ https://online.epocrates.com/diseases/1202/Heparin-induced-thrombocytopenia]
Progressive thrombosis #criteria
Note: In 4 Ts score: • Confirmed new thrombosis, skin necrosis, or acute systemic reaction after intravenous unfractionated heparin bolus – 2 points • Progressive or recurrent thrombosis, non-necrotizing (erythematous) skin lesions, or suspected thrombosis that has not been proven – 1 point • None – 0 points
Ref: Uptodate [ Clinical presentation and diagnosis of heparin-induced thrombocytopenia] Epocrates [ https://online.epocrates.com/diseases/1202/Heparin-induced-thrombocytopenia]
Pruritic erythematous plaques without necrosis (negative symptom)
Ref: Uptodate [ Clinical presentation and diagnosis of heparin-induced thrombocytopenia]

Lab / Serology

 Thrombocytopenia #criteria
Note: The platelet count does not have to fall below 150 × 10⁹/L for HIT to be considered
Ref: Uptodate [ Clinical presentation and diagnosis of heparin-induced thrombocytopenia] Epocrates [ https://online.epocrates.com/diseases/1202/Heparin-induced-thrombocytopenia]
Thrombocytopenia occur within the first 24-48 hours (negative symptom)
Ref: Epocrates [ https://online.epocrates.com/diseases/1202/Heparin-induced-thrombocytopenia]
Dermal microvascular thrombi
Ref: Uptodate [ Clinical presentation and diagnosis of heparin-induced thrombocytopenia]

Imagin Study

 Persistent thrombosis lasts weeks after stopping heparin #Refractory_HIT #persistent_HIT
Ref: Uptodate [ Clinical presentation and diagnosis of heparin-induced thrombocytopenia]
Flow defect within dural sinuses
Note: Should be performed in patients with suspected cerebral venous thrombosis (=CVT)
Ref: Epocrates [ https://online.epocrates.com/diseases/1202/Heparin-induced-thrombocytopenia]
Multiple segmental defects seen with normal ventilation
Note: An alternative to computed tomography pulmonary angiogram (CTPA)
Ref: Epocrates [ https://online.epocrates.com/diseases/1202/Heparin-induced-thrombocytopenia]

Complication

 Stroke #criteria
Note: In 4 Ts score: • Confirmed new thrombosis, skin necrosis, or acute systemic reaction after intravenous unfractionated heparin bolus – 2 points • Progressive or recurrent thrombosis, non-necrotizing (erythematous) skin lesions, or suspected thrombosis that has not been proven – 1 point • None – 0 points
Ref: Uptodate [ Clinical presentation and diagnosis of heparin-induced thrombocytopenia] Epocrates [ https://online.epocrates.com/diseases/1202/Heparin-induced-thrombocytopenia]
MI
Ref: Uptodate [ Clinical presentation and diagnosis of heparin-induced thrombocytopenia]
Chills #criteria
Note: Due to Acute systemic reaction, Due to Anaphylaxis
Ref: Uptodate [ Clinical presentation and diagnosis of heparin-induced thrombocytopenia] Epocrates [ https://online.epocrates.com/diseases/1202/Heparin-induced-thrombocytopenia]

Risk Factors

 Elder
Ref: Uptodate [ Clinical presentation and diagnosis of heparin-induced thrombocytopenia]
Female
Ref: Epocrates [ https://online.epocrates.com/diseases/1202/Heparin-induced-thrombocytopenia]

Cause

Other