The invention provides diagnostic methods, kits, and systems, and related computer-readable media, which use multiple blood marker values, including serum and plasma marker values, to aid in the diagnosis of the status or progress of a liver disease in a patient.The invention also provides methods and systems, and related computer-readable media, that use blood marker values, including serum and plasma marker values: (1) to screen for active ingredients useful in the treatment of a liver disease; (2) to aid in the selection of treatment regimens for patients that are predisposed to, or suffer from, liver disease; and (3) to aid in the design of clinical programs useful in monitoring the status or progress of liver disease in one or more patients.