Abstract: A lateral flow method for the determination of an analyte in a sample utilizes biospecific affinity reactions. The method comprises forming a complex comprising Reactant I - - - Analyte? - - - Reactant* wherein Reactant* and Reactant I exhibit biospecific affinity to the analyte, Reactant* is analytically detectable, and Analyte? is the analyte or an analyte-related reactant, determining a detectable signal from Reactant* in the complex (sample value), and obtaining the amount of analyte in a sample by comparing the sample value with one or more calibrator values, each of which corresponds to a standard amount of analyte. Before determination of the calibrator value, either calibrator or a binder for the calibrator has been bound to a matrix and is released at the determination of calibrator value.