A blood analysis system functions as a non-invasive blood parameter analyzer when a monitor is coupled with an optical sensor and as an invasive blood sample analyzer when the monitor is coupled with a blood analysis adapter. The blood analysis adapter has a transmitting assembly and a receiving assembly in electrical communications with the adapter connector so as to receive emitter signals for driving emitters within the transmitting assembly and so as to transmit a detector signal for responding to at least one detector in the receiving assembly. A cuvette containing a blood sample is irradiated with multiple wavelength light from the emitters, the detector responds to the multiple wavelength light after attenuation by the blood sample, and the monitor analyzes the blood sample according to the detector signal.