First and foremost, she needs to get herself to safety from her boyfriend and talk to a professional about this situation.
The thyroid can be damaged by trauma such as choking and lead to a thyroiditis.
Hi,
Check out www.emedicinehealth.com/thyroid_problems/page4_em.htm
Untreated hypothyroidism - (is she HYPO or HYPER thyroid?) can cause severe effects on brain and can cause intestinal obstruction as well as heart problems. This site also goes on to say that and infection or TRAUMA can make it worse. Check it out and maybe send her a link. I admire you for wanting to help your friend - but I have to say - it will be hard. I have a friend that I have known for over 25 years - and she is still on again off again with the same jerk who chokes her and slaps her around. I am waiting for a call from her mom telling me she's dead....hate to say it but it wouldn't surprise me. It drove me nuts for a while - I just couldn't understand why she would stay with someone like that - but I finally figured out that I couldn't make her do anything - all you can do is give her the info - it is up to her to change her life. I will keep you both in my thoughts and prayers.
Peace to you,
Charley