Immunological assays for several biological markers for thyroid disorders in a biological sample are performed in a single test with a combination of sandwich-type, sequential competitive, and serological assays by the use of particles classified into groups that are distinguishable by flow cytometry, one group for the assay of each marker. Each group of particles is coated with a different immunological binding member, and coating densities, co-coating materials, and special buffer solutions are used to adjust for differences in the sensitivities and dynamic ranges of each of the markers in the typical sample.