An inj ectate for use in a method for measuring a biometric indicator of a mammalian subject, the inj ectate comprising (i) a first fluorescent tag having a first excitation wavelength and a first emission wavelength; (ii) a second fluorescent tag having a second excitation wavelength and a second emission wavelength, wherein both first and second fluorescent tags are conjugated to a static molecule, or wherein the first fluorescent tag is conjugated to the static molecule and the second fluorescent tag is conjugated to a dynamic molecule; and (iii) an inj ectate carrier wherein the method for measuring a biometric indicator comprises: (a) calibrating an inj ectate to obtain a calibration identification of the inj ectate that contains parameters of the inj ectate, (b) inputting the parameters of the calibration identification of the injectate to a fluorescent detector to calibrate the fluorescent detector; (c) determining existing level of fluorescence in the mammalian subject; (d) introducing the inj ectate into the vascular system of the mammalian subject; (e) exciting the first fluorescent tag with a first excitation wavelength and exciting the second fluorescent marker with a second excitation wavelength at an optical interface of an optical probe and the vascular system, or in a sample taken from the vascular system; (f) measuring the first emission intensity of the first emission wavelength of the first fluorescent tag and measuring the second intensity of the second emission wavelength of the second fluorescent tag at the optical interface of the optical probe and the vascular system, or in the sample taken from the vascular system, using the calibrated fluorescent detector, to obtain a spectrometric data set, which includes a first emission fluorescent intensity curve from the first fluorescent tag and a second emission fluorescent intensity curve from the second fluorescent tag; (g) periodically repeating steps (c) through (f); and (h) calculating the biometric indicator of the mammalian subject as a function of the first and second emission intensities measured in (f) and relative to the existing level of fluorescence measured in (c). (i) a first fluorescent tag having a first excitation wavelength and a first emission wavelength; (ii) a second fluorescent tag having a second excitation wavelength and a second emission wavelength, wherein both first and second fluorescent tags are conjugated to a static molecule, or wherein the first fluorescent tag is conjugated to the static molecule and the second fluorescent tag is conjugated to a dynamic molecule; and (iii) an inj ectate carrier (a) calibrating an inj ectate to obtain a calibration identification of the inj ectate that contains parameters of the inj ectate, (b) inputting the parameters of the calibration identification of the injectate to a fluorescent detector to calibrate the fluorescent detector; (c) determining existing level of fluorescence in the mammalian subject; (d) introducing the inj ectate into the vascular system of the mammalian subject; (e) exciting the first fluorescent tag with a first excitation wavelength and exciting the second fluorescent marker with a second excitation wavelength at an optical interface of an optical probe and the vascular system, or in a sample taken from the vascular system; (f) measuring the first emission intensity of the first emission wavelength of the first fluorescent tag and measuring the second intensity of the second emission wavelength of the second fluorescent tag at the optical interface of the optical probe and the vascular system, or in the sample taken from the vascular system, using the calibrated fluorescent detector, to obtain a spectrometric data set, which includes a first emission fluorescent intensity curve from the first fluorescent tag and a second emission fluorescent intensity curve from the second fluorescent tag; (g) periodically repeating steps (c) through (f); and (h) calculating the biometric indicator of the mammalian subject as a function of the first and second emission intensities measured in (f) and relative to the existing level of fluorescence measured in (c).