Measuring devices are disclosed for determination of at least one parameter of a blood sample. The measuring device includes a flow-through measuring cell, in which is disposed luminescence-optical sensor elements, which can be brought into contact with the blood sample, and at least one light source for excitation of the luminescence-optical sensor element and at least one photodetector for receiving the luminescence radiation emitted by the luminescence-optical sensor element. The light source and the photodetector are located on opposite sides of the flow-through measuring cell. The sensor elements are placed on an excitation side of the flow-through measuring cell, which faces the light source, and the light source emits excitation radiation of wavelength less than 600 nm, while the luminescence radiation of the sensor elements lies in a wavelength range greater than 600 nm, thus exposing the excitation radiation to stronger absorption by the blood sample than the luminescence radiation.
