The invention relates to a test kit for better carrying out a method for detecting biomarkers in human or animal stool, which can serve as an indication of a pathological, particularly a malignant event in the gastrointestinal tract (esophagus, stomach, small bowel, biliary tract, pancreas, and bowel).The invention teaches a novel and more efficient methods, uses and embodiments of a combined rapid test. The combined rapid test cassette used for implementing the test kit and the optimally coordinated reagents thereof contains two lateral flow test strips for the synchronous—in the technical meaning—detection of the biomarkers M2-PK and the biomarker hemoglobin.The test serves as a “dual filter” for diagnosing probands as part of a colon cancer screening program. The test is very cost-efficient and cuts costs in the health system by the examination at an early stage of colon cancer and the consequences thereof.