Editing Thrombosis

== '''Thrombophilia''' ==

* Present in about 5% of the population, but most never get VTE

=== HERITABLE thrombophilia screen: ===

** Factor V Leiden
** Prothrombin gene mutation
** Protein S
** Protein C
** Anti-thrombin
** (Protein S, C and anti-thrombin levels are impacted by acute thrombosis so might need to check it again later)
**

*

*

=== ACQUIRED thrombophilia ===

** Anti-phospholipid antibodies (lupus anticoagulant, anti-cardiolipin antibody and anti-B2 glycoprotein I antibody)
*** Test if VTE is unprovoked or in an unusual site
*** Patient has a concomitant autoimmune disorder, previous arterial thromboses including CVA/MI, or a history of recurrent pregnancy failure or fetal death
*** Testing for lupus anticoagulant can be affected by DOAC (false positive)
** Underlying myeloproliferative disease
*** Suspect with splanchnic vein thromboses or VTE in another unusual site
*** Can be present despite normal blood counts
*** Test is JAK2 kinase
*** Consider CALR mutation testing and a BM biopsy if JAK2 is negative in patients with a high index of suspicion
** Consideration of malignancy
*** 10% of those with unprovoked VTE will be diagnosed with cancer in the first year
*** Medical history
*** Examination
*** FBE, calcium, LFts
*** CXR
*** Mammogram
*** Pap smear
*** PSA
*** NBCSP
*** Routine CT and tumour markers is not recommended, according to the Austin guidelines, but can be done depending on risk and clinical scenario
** Hyperhomocysteinaemia - testing not recommended routinely

== '''Anticoagulants in thrombosis''' ==

* DOAC - 3/12 is shortest acceptable treatment for provoked DVT
** Apixaban 10mg BD for one week then 5mg BD
** Rivaroxaban 15mg BD for 3 weeks then 20mg daily
* Warfarin preferred if: (starting dose 5mg daily in most patients)
** Weight 120kg or BMI >40
** Weight less than 40kg
** APLS
** Mechanical heart valve
** Any contraindication to DOAC, including eGFR <30
* Warfarin starting dose 5mg daily in most patients. Need to bridge while loading for patients with VTE, until INR >2 for 2 consecutive days
* Enoxaparin - primarily for cancer-related thrombosis, pregnancy and superficial vein thrombosis. 1mg/kg BD or 1.5mg/kg daily.
** Check enoxaparin anti-Xa levels in patients with renal failure, extremes of weight, suspected non-compliance or overdose. Therapeutic level (peak, 4 hours post dose) is 0.5-1.0 units/mL if on a twice daily regimen.
* Unfractionated heparin
** Primarily used when rapid onset and offset is desired
** Plasma heparin anti-Xa level can be used to guide dosing in some patients:
*** Failure to achieve an APTT result within the therapeutic range after 24 hours
*** Heparin resistance (i.e., requirement of >35,000 units of UFH per 24 hours to achieve an APTT result within therapeutic range)
*** Lupus anticoagulant (prolongs baseline APTT)
*** >100kg
*** Pregnant
*** Need to achieve therapeutic range rapidly
*** Markedly raised acute phase reactants


== '''VTE Prophylaxis''' ==
The only surgical patients that don't get chemoprophylaxis (assuming no contraindication) are those with surgery <30 mins and NO risk factors


Risk factors

* Acquired
** Previous VTE
** Malignancy
** Surgery
** Trauma
** Immobilisation
** Age >65
** Pregnancy
** Chronic inflammatory bowel and liver disease
** Cardiovascular disease
** Drugs - hormonal, cancer therapy
** Antiphospholipid antibodies
** Kidney disease
** Haematologic conditions
* Inherited
** Thromobophilia
** Anatomic
*** Varicose veins
*** Paget-Schroetter syndrome
*** May-Thurner syndrome
*** IVC abnormalities

[[Category:Haematology]]