Prognostic Value Serum Concentration of Indoxyl Sulfate During Acute Kidney Injury in Septic Shock Patients.

Inclusion Criteria: * Patients over 18 years hospitalized in the medical intensive care unit in Amiens university hospital * Presence of a septic shock (sepsis associated with a persistent hypotension after fluid resuscitation and requiring vasopressors to maintain MAP \> 65 mmHg and/or serum lactate level \> 2 mmol/ L). * Evidence of AKI (KDIGO \> or equal1) in the 72 hours following the admission in the ICU: diuresis \< 0.5ml / kg / h for 6 to12 hours or \> or equal 1.5 to1.9 fold increase or \> 26.5 micromol / l in serum creatinine from baseline * signed written informed consent form * covered by national health insurance Exclusion Criteria: * known pre hospitalization (in the last 3 month preceding the hospitalization) advanced chronic kidney disease defined by an estimated glomerular filtration rate \< 60 ml / min / 1.73m square * Pregnancy * Presence or strong clinical suspicion of renal obstruction * Moribund patients (expected life \< 48h) * Cardio respiratory arrest * Hemoglobin level below 10 g / dl