An apparatus for extracorporeal blood treatment for chronic therapy comprises a nutritional bag (33) containing a nutritional solution, a weighing device (36) configured to determine a weight (W) of the nutritional bag (33), a nutritional line (34) for infusing the nutritional solution into either a blood return line (7) or into the patient vascular system. An ultrafiltration device (30) is configured to achieve a fluid removal from the patient through a semipermeable membrane (5) of a filtration unit (2) and a sensor (31, 32) is configured to determine an ultrafiltration rate (UFR). A control unit (100) connected to the ultrafiltration device (30), to the weighing device (33) and to the sensor (31, 32) is programmed for receiving a patient prescription and for controlling the ultrafiltration device (30) to achieve the patient prescription based on the weight (W) and on ultrafiltration rate (UFR).
