A multi-analyte diagnostic system for use with a computer (900). The diagnostic system includes a flow analyzer (25) including a co-planar light source-optical detector array (120), the flow analyzer being communicatable with the computer (900). The diagnostic system also includes a memory medium readable by the computer (900) and storing computer instructions. The instructions include the following steps. A biological sample is run through the flow analyzer (25). The identity and quantity of at least one analyte of interest in the biological fluid is determined substantially simultaneously to the sample-running step.