Inclusion Criteria:  All patient requiring Renal replacement Therapy  Exclusion Criteria:  Age < 18 years Pregnancy Hypercalcemia ≥ 3 mmol/L. Major under guardianship Major deprived of liberty Impossible to obtain free and informed consent Presence of hemostasis or coagulation disorders: Thrombocytopenia < 30 G/L. Curative anticoagulation. Severe liver disease with PT<30%. Coagulation factor deficit. Non-membership in a social security system.