The present invention pertains to Method for monitoring a dialysis treatment of a patient, preferably for monitoring a haemodialysis, haemodiafiltration and/or peritoneal dialysis treatment of a patient, the method including the steps of: irradiating a sample of a dialysis fluid used in the dialysis treatment with linearly polarized irradiation light; detecting the intensity of the fluorescence light emitted by the dialysis fluid in a first polarization plane; detecting the intensity of the fluorescence light emitted by the dialysis fluid in a second polarization plane which is different from the first polarization plane; determining the anisotropy of the fluorescence light emitted by the dialysis fluid; and determining the concentration of at least one fluorophore in the dialysis fluid on the basis of both, the determined anisotropy and the intensity of the fluorescence light emitted by the dialysis fluid.