**Abstract**

Renal replacement therapy (RRT) ensures the removal of water and solutes that are not or no longer sufficiently ensured by the kidneys: Acute renal failure (AKI) remains the oldest indication, regardless of the patient's age. All the methods of extracorporeal purification (peritoneal dialysis, conventional hemodialysis, and continuous extracorporeal purification) have been developed in children to compensate for renal function when it becomes totally or partially inadequate, and primarily or secondarily the RRT must be initiated without delay in life-threatening situations (hyperkalemia, metabolic acidosis, lysis syndrome, pulmonary edema refractory to medical treatment…). There are insufficient data to define the optimal time for initiation of RRT outside of life-threatening situations. Despite the lack of specific studies, the benefit of ERA in life-threatening situations seems reasonable, which is why most experts recommend its use in these situations. The CRRT has proven its effectiveness in pediatrics. The continuous and progressive nature of CRRT, particularly hemofiltration, makes it the therapy of choice for unstable ICU patients. The choice of the RRT method in a given center is therefore based on the type of patient to be treated, but also on technical availability, experience, and local skills.

**Keywords:** child, neonate, peritoneal dialysis, salt and water depletion, hemodiafiltration, continuous extrarenal therapy
