Manchester United revealed yesterday that Fletcher had compromised his own recovery from a chronic bowel complaint in order to do his duty for club and country.
However, with the 27-year-old's situation giving cause for concern once more after another absence, previously attributed by the club to "a virus", the decision has been made for Fletcher to stand down.
"I am obviously absolutely devastated for Darren because I know how hard he has worked to get back to playing regularly for his club and country," said Levein.
"He is one of the most inspirational players I have had the pleasure of working with.
"I spoke with Sir Alex Ferguson and Darren this week and the most important thing at this stage is for the player to be given time to rest and recuperate.
"He is a central part of our plans for the World Cup 2014 qualifiers but at this stage his health is paramount."
A thoroughly likeable individual, there will be few who do not share the hope Rio Ferdinand expressed on Twitter that Fletcher eventually makes a full recovery.
Other athletes, including Sir Steve Redgrave, have maintained top level sporting careers despite health problems.
However, as the 'attacks' are so varied in strength and deeply personal, a full recovery is by no means guaranteed.
"Whilst he (Fletcher) was able to maintain remission of symptoms for a considerable period this has proved more difficult recently and Darren's continued desire to play and his loyalty to both his club and country has probably compromised the chances of optimising his own health and fitness," said a statement issued by United.
"He has therefore accepted medical advice to take an extended break from the demands of training and playing in order to afford the best chance possible of achieving full remission once again."
Aside from genuine concern for his fellow countryman, for Sir Alex Ferguson it exacerbates an already acute shortage of bodies in his midfield ahead of the packed festive programme.
It is anticipated Tom Cleverley will return during the Christmas campaign.
However, with Anderson currently sidelined and skipper Nemanja Vidic ruled out for the rest of the season with a knee injury, yesterday's news may force United to revise their previously stated intention of not buying in January unless Ferguson intends offering Paul Pogba and Darron Gibson a far more prominent role than had originally been envisaged.