How do thiazides cause hypercalcaemia?

I was discussing with a renal consultant the reasons for avoiding thiazides in patients with sarcoidosis with renal involvement. I think it is well established that they can cause hypercalcaemia but after (not very much) searching on the internet and in textbooks I can't seem to find out why? Does anybody know?

Authored By Amy Huxtable on Sunday 19th January 2014