1. An automated medical diagnostic system, comprising: a graphical user interface (GUI) displaying a matrix of cells, each cell being representative of a patient health item (PHI) associated with a particular disease, wherein a first axis of the matrix of cells is organized according to standard anatomic systems and a second axis of the matrix of cells is organized according to different parts of a medical workup; and a processor programmed to execute a plurality of diagnostic functions, said processor uses the matrix for input from a user of the GUI, wherein the processor selectively executes the diagnostic functions according to each newly input PHI so as to result in and display a list of possible diagnoses and updated differential diagnosis, wherein: one or more cells is representative of a nested matrix of selectable cells, each cell of the nested matrix being representative of at least one disease associated with a subset of the cause of disease acting on an anatomic subsystem of the body; when the processor determines that a newly input PHI renders a particular disease impossible to reach a diagnostically significant threshold, the processor removes the particular disease from further consideration in the differential diagnosis and disables the particular disease from suggesting additional PHIs; and when the processor determines that a diagnostically significant threshold is reached, the processor segregates any diseases that do not meet or exceed such threshold from suggesting additional PHIs.