A modular hand-held point of care testing system, which includes a plurality of different assay adapters configured to receive a plurality of different assay devices that perform assays on one or more samples; a shared door that that interchangeably receives the plurality of different assay adapters; wherein at least two of the plurality of assay adapters or at least two of the assay devices comprise different identifiers that distinguish the assays from each other; an apparatus comprising a portable frame configured to interchangeably receive the shared door and a means for decoding the different identifiers when received by the frame; and a means for reading assay results.