Thrombophilia is a broad medical term which describes a multifactorial condition where the blood has an increased tendency to clot. Individuals with thrombophilia can present with arterial or venous thrombosis. The causes of thrombophilia include inherited and acquired disorders, and a combination of causes may be present.
Inherited causes of thrombophilia may be discovered through family testing. These include:
- Antithrombin, Protein C and Protein S deficiency
- Factor V Leiden and prothrombin gene mutations
Acquired causes of thrombophilia may present later in life and can be associated with:
- Malignancy including myeloproliferative neoplasms
- Antiphospholipid syndrome and other autoimmune connective tissue disorders. These may be associated with a lupus anticoagulant and/or anti-cardiolipin antibodies on laboratory testing.
Retinal Vein Thrombosis (also known as Retinal Vein Occlusion) is a form of retinal vascular disease and can affect central or branch retinal veins. The condition is uncommon under the age of 60 but becomes more frequent in later life. The condition may be associated with risk factors including hypertension, hyperlipidaemia, diabetes mellitus, atherosclerosis, and smoking.
VITT, TTP and HIT are rare disorders characterised by arterial or venous thrombosis in combination with a low platelet count (due to platelet consumption). Donors who recover from these disorders are unlikely to be eligible to donate due to the therapy they received (e.g the primary treatment for TTP is plasma exchange with FFP) or an underlying condition (e.g. the indication for Heparin therapy that triggered HIT). VITT was recognised as a complication of some SARS-CoV-2 (COVID-19) vaccinations.
Axillary Vein Thrombosis can be precipitated by excessive use of the arm (e.g. sports or working above head level) but other precipitants include venous compression in thoracic outlet syndrome, diabetes, smoking, malignancy and venous canulation. The donor may be eligible to donate if the underlying cause has been identified and corrected, but this should be balanced with the remote risk of local complications from a subsequent donation.
Superficial thrombophlebitis, also known as superficial vein thrombosis, is a common condition usually, but not exclusively, affecting the lower limbs. It is characterised by inflammation in a superficial vein associated with clot formation. This is different to, and less serious than, a deep vein thrombosis (DVT). If the superficial clot extends to where the superficial and deep veins join, a DVT can develop. Superficial thrombophlebitis normally settles within two to six weeks. Some individuals may be treated with anticoagulants to reduce the risk of extension. Recurrent superficial thrombophlebitis is sometimes associated with a diagnosis of thrombophilia.
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