Inclusion Criteria:  Age > 18 years; septic shock according to ACCP/SCCM criteria AKI KDIGO stage 3 clinical decision to begin citrate based-RRT for at least 48 hours Hb >= 9 g/dL Obtain the informed consent  Exclusion Criteria:  Pre-existing chronic renal insufficiency Weight > 125 kg Life expectancy <24 hr Declared do Not Resuscitate or Comfort Measures Platelets < 20 [10^3/ul] or active bleeding Pregnancy Contraindication to citrate