Adrenal gland or suprarenal gland (US English)

I am not aware of any difference between American and UK usage of that word, I am sure most of the American journals I read on the topic referred to the Adrenals andsuprarenals equally and interchangeably but the last time I read anything on the topic was more than 10 years ago now so I may be remembering wrong.

If you want to check, either look at a recent American medical text book (google scholar may be able to help you there) or do a search on PubMed (google 'Entrez PubMed' then search for 'adrenal gland' and 'suprarenal gland' in the search engine there and pick a couple of abstracts to look at - check the publication country/location of university and see what they use.)

As an USian, in my experience the average person is more likely to be familiar with "adrenal gland".

Unless there's a solid reason to do otherwise, even my doctor just says adrenal gland.

Adrenal.

Suprarenal probably shows up in medical journals, but rarely anywhere else. I don't think I've ever seen it used.