Just heard a trail for this program on Radio 4 this week.
In the book, there is a thyroid issue (that's the on-topic bit!) - obviously I don't know if it made the cut of translation to radio. Also, it is interesting as a description of medicine in the pre-war, pre-NHS era. With everything that implies.
10:45 Episode 1
15 Minute Drama, The Citadel Episode 1 of 5
By A J Cronin. Dramatised by Christopher Reason
Episode 1
Andrew Manson, a newly trained doctor arrives in Drineffy, a South Wales mining town. He is to be an assistant to the elderly Dr Page. Manson is idealistic and full of enthusiasm but this is soon tempered by reality when he meets the cynical Dr Denny another doctor in the town.
Set in the mid 1920s and based on A J Cronin's ground breaking novel, which partly inspired Nye Bevan to create the NHS.
In my view, the book is well worth reading. I hope the radio dramatisation works well. The book deserves it.