The invention provides immunochromatographic test strips and methods and systems or kits for detecting and quantifying S-Adenosylmethionine (SAM), S-Adenosylhomocysteine (SAH) and Homocysteine (HCy) in a sample, comprising: (a) making fluorophore conjugated antibodies; (b) immobilizing SAM, SAH and HCy on a solid support; (c) providing a sample, combining said sample with a conjugate selected from the group consisting of lanthanide chelate conjugates and quantum dot conjugates (QD) with anti-SAM, anti-SAH or anti-HCy, wherein said combining is performed under conditions that allow formation of a competitive complex comprising said conjugate, said SAM, SAH or HCy on the solid support and SAM, SAH or HCy in a sample when present; and (d) detecting the presence of the complex, if present, by monitoring a spectral emission mediated by the fluorescent conjugates in the complex, wherein the emission indicates the presence and quantity of SAM, SAH or HCy in the sample.