From discovery in 1922 Vitamin D has undergone a metamorphosis from a nutrient to a hormone to a cytokine. Indeed it is an exciting time to be involved in vitamin D research and nothing I will say in the context of this debate will seek to discredit anything my learned colleague will undoubtedly present regarding our evolving insight into Vitamin D’s place in human biology, health and disease. On that basis alone the increase in vitamin D testing that has occurred in the last decade is understandable. Coupled with changes in how we define vitamin D deficiency and the wider availability of automated assays there has been an explosion in the number of tests performed in routine clinical practice. But there are differences between cautious optimism, measured enthusiasm and irrational exuberance. Something can be said to be overrated when it is given too much credit and we overestimate its merits; when it is hyped; when we rate it too highly.

But how high is too high? Fortunately we have a hierarchic set of principles to guide us. We are endocrinologists. Our approach is supposed to be scientific and our conduct is supposed to follow a well established model of observation, hypothesis generating and testing behaviour preordained by our forebears.

With great prescience Andy Warhol’s prediction that "in the future, everyone will be world-famous for 15 minutes” is based on the idea that the "hierarchy of subjects worthy to be represented will someday be abolished." Hence anybody and anything can be famous, not merely that which is worthy of fame, once that hierarchy dissipates. That was 1968. Witness today the phenomenon of celebrities who are famous for being famous! In 2013 I contend we are on the precipice of abandoning scientific rigour and the habit of repeat measurements of Vitamin D in clinical practice are unfettered snapshots that risk reducing it to the analytical equivalent of twittering? Perhaps interesting and possibly newsworthy, at times unfathomable but definitely overrated.