AVP and clostridium difficile infection: Recently, the diagnostic performance of the test measuring copeptin, the C-terminal segment of the AVP prohormone which can be precisely measured as opposed to AVP per se, osmotically stimulated either by water deprivation or by hypertonic saline infusion, was proven to be superior to the classic indirect water-deprivation test in distinguishing CDI from primary polydipsia in patients with hypotonic polyuria [84].