Thyroid UK

Can half a thyroid work as well as a full thyroid?

My sister-in-law had half of her thyroid removed to remove a growth. I was quite surprised to learn this weekend that she is not on any medication for hypothyroidism; can half a thyroid work as well as a full thyroid?

I'm just quite interested, and a little worried that she may have been left with half a thyroid which is struggling to cope without any medication, or doesn't it work like that. I certain think she did suffer with hypothyroidism before her surgery as she wasn't herself and gained quite a lot of weight which was not usual for her as she had always been petite.

If anyone has any comments or experience with part removal of a thyroid I would be interest to hear from you.

3 Replies

Extract from the following link:-

Will I have to take medication if I still have half of my thyroid?

Approximately 1/2 - 3/4 of patients that have half a thyroid will not need hormone replacement. However, there are no accurate predictors of who will need medication and who will not.

Your thyroid function will be tested about six weeks after surgery and a determination will be made at that time.


That's great, thank you; feel a little better now as I was quite worried.


Hi, I had a partial thyroidectomy in Oct 12. I started feeling poorly 4wks later but my dr would not blood test until end Jan. My TSH had gone from 1.5 pre op to 4.95 3 months after and 2 1/2stones weight gain. I was told to come back for a blood test 6 months later. I returned the next month feeling even worse and TSH was 6.98. I was put on a low dose of levo.

I was told my half thyroid would 'pick up the slack' and compensate for the removed half. This hasn't been the case for me but it's very reassuring that your sis in law has remained the same. She may find it useful to keep a record of her blood test results or keep a diary of how she is feeling.


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