Method of detecting presence of analyte in biological sample

The present invention relates generally to a method of detecting the presence of an analyte in a biological sample. A first method for detecting blood in a biological sample involves applying a sample to a first region of a test matrix, detecting globin or haemoglobin by means of an immunological test in a second region of the test matrix and detecting haem by means of a chromogen based test in a third region of the test matrix. This method is capable of differentiating between upper and lower gastrointestinal tract bleeding and is useful for the diagnosis of gastrointestinal tract diseases, in particular, lower gastrointestinal tract diseases such as colorectal cancer. A second method disclosed involve s applying a sample to a first region of a test matrix, the sample is allowed to flow to a second region where it contacts an anti-analyte immunointeractive molecule and a labelled anti-analyte immunointeractive conjugate. Any analyte-anti-analyte complex that is formed is immobilised and detected in this second region, any uncomplexed labelled anti-analyte immunointeractive conjugate is allowed to flow to a third region where it is detected.