In a screening test method, and a device for implementing the screening test method, a diagnostic substance is provided that contains at least one biomarker connected with at least one ferromagnetic particle, the biomarker binding specifically to a target molecule that is formed by specific pathological prostrate tissue. The diagnostic substance is administered to the blood stream of a patient. A magnetometer is used to detect enrichment of the ferromagnetic particle in the prostrate, as an indicator of a level of the specific pathological prostrate tissue.