Abstract

Theranostics or theragnostics are new terms which start to appear occasionally in publications from 2001 onwards, with a marked increase in references from 2011. In the last few years more than 1100 articles using this term were published each year. In 2011 the journal Theranostics was founded. This paper addresses the question of whether this new term is appropriate. The etymology of the term is analysed. A literature search for definitions of “theranostics” is carried out and the definitions examined as to whether they give grounds for justifying the use of a new term. The differences between diagnostics and therapy are explored. A broad and a narrow definition are found. According to the broad definition theranostics provides a closer relationship between diagnostics and therapy. According to the narrow definition diagnostics and therapy become a single intervention. On closer examination it turns out that in the narrow definition the diagnostics capacities are limited to monitoring. Neither the broad nor the narrow definition actually demonstrate a new concept in medicine. Rather, they describe the well-known practice of medical decision making. In this respect, the new term cannot be justified. The level of diagnostics is new but not the relationship between diagnostics and therapy. The term theranostics is misleading as it obscures the existing differences between diagnostics and therapy and wrongly insinuates that steps between diagnostics and therapy could be omitted.