The invention provides a method for detection of active form of analytes in a sample, comprising the following steps : a) analyte or group of analytes from the sample is immobilized on the surface of a solid carrier either by non-specific non-covalent adsorption or by covalent binding of surface functional groups of the analyte and corresponding functional groups of the solid carrier, or preferably via a binding molecule which is bound to the surface of the solid carrier before immobilization of the analyte or group of analytes and is capable of selectively binding the analyte or group of analytes contained in the sample during incubation of the solid carrier with the sample; b) analyte or group of analytes is incubated with a detection probe which binds selectively to the analyte or group of analytes via a compound for selective binding to the analyte active site; whereas the probe consists of a low molecular compound for selective binding to the analyte active site; an oligonucleotide tag, optionally with a covalently attached fluorophore, biotin or a chemical group, and a chemical linker covalently linking the compound for selective binding to the analyte active site and the oligonucleotide tag; c) then the solid carrier is washed to remove unbound detection probe; and subsequently, the amount of bound detection probe is determined, whereas this amount is directly proportional to the amount of the analyte or group of analytes in the sample. The described method has broad application in medicine. Given the exceptional sensitivity of only a few dozen molecules, it provides the ability to determine the protein markers in blood in a concentration yet undetectable.