Lateral flow test strips, systems, and methods are provided for measuring the presence and levels of analytes in samples in which the analyte may be complexed, for example within an analyte-antibody complex. Test strips are provided that can decomplex the analyte from the analyte-antibody complex during the lateral flow assay, resulting in high quality assays without the need for a decomplexation pre-treatment step. Various systems and methods for improving the performance of lateral flow assays are described, which include minimization of the Prozone effect, improved dynamic range, improving sensitivity by disrupting complexation of target antigens. The resulting lateral flow system has improved sensitivity and improved dynamic range, and may utilize fluorescence. The illumination system utilizes an LED, plastic lenses and plastic and colored glass filters for the excitation and emission light.