Anticoagulants influence either coagulation, inflammation and inflammatory processes in deep vein thrombosis (DVT). Acute DVT cause an inflammatory response that may persist for a long period of time. There is a need to describe patterns of change in serum biomarker levels after acute DVT, and explore the association between trajectory biological patterns and clinical evolution in the era of various anticoagulants in the acute phase of treatment in order to be able to further avoid recurrence and late sequelae. It appears that direct oral anticoagulants and heparin alter inflammatory markers in different ways. It is therefore important to study the evolution of markers according to the different treatments used and secondarily to compare them with each other. Tinzaparin is used in the long term in patients with DVT, it is necessary to measure the evolution of inflammatory markers and then in another study to compare with the other molecules.

Inclusion Criteria:

• Adult patients with a first episode of symptomatic, proximal DVT of the lower limbs, confirmed by Duplex Ultrasound (DUS)
• Indication for treatment with Tinzaparin
• Patient covered by French national health insurance,
• Written informed consent.

Exclusion Criteria:

• Recent DVT (less than 2 months) objectively proven by venous ultrasound - Severe ilio-femoral DVT requiring recanalization
• Duration of treatment of more than 24 h since diagnosis
• Patients with acute symptoms (leg pain and swelling) for more than 5 days
• Planned surgery in the following 3 weeks, impossible to postpone
• Active haemorrhage or high risk of haemorrhage
• Symptoms of Post Thrombotic Syndrome
• Active neoplasm
• APL syndrome
• Renal insufficiency (Creatinine clearance (Cockcroft-Gault) <20 mL/min)
• Hepatic disease / or Hepatic Insufficiency / or serious liver disease
• Hyperkaliemia more than 5 mmol/L
• Patients with mechanical prosthetic heart valve
• weight more than 105 kgs in order to avoid difficulties with a dosage of 20000UI OF TINZAPARIN Any anti-inflammatory drugs or anti-platelet therapy
• Any other concomitant anticoagulant treatment such as VKA, heparin, fondaparinux and direct oral anticoagulants
• Contraindications to tinzaparin according to their SmPC
• Patient with asthma, If patients need to receive tinzaparin 10000UI antiX-a/0.5ml for the study,(due to sodium metabisulfite in the solution)
• Pregnant women or breastfeeding
• patient with age under 18
• Patient deprived of liberty by administrative or judicial decision or placed under judicial protection (guardianship or supervision)