This has been a pet peeve of mine for a while. But I'm sure there's a grammatical reason for this I've just never picked up.
It's the way the media refer to the Ministry of Health, calling it the Health Ministry. Eg:
http://www.stuff.co.nz/national/politics/2750683/Plan-to-gut-Health-Ministry
vs
http://moh.govt.nz/moh.nsf
Can someone please explain to me why they do it that way?