Inclusion Criteria:  Age ≥18 years; Hemodialysis treatment in the UMCG or DCG; Dialysis vintage ≥2 months; Conventional hemodialysis, thrice weekly treatment with three to five hours per dialysis treatment; Hemoglobin at previous routine monthly assessment greater than or equal to 6.5 mmol/l; Signed informed consent.  Exclusion Criteria:  Pregnancy; Presence of clinical signs of infection; Confirmed diagnosis of malignancies; Incapacity of the Dutch language; Inability to complete questionnaires; Short life expectancy; Kidney transplantation planned within 3 months.