My daughter has a mulitnodular goitre discovered 3 years ago at age fifteen and also just diagnosed with poly cystic ovary syndr

Miss Mouse, what do your daughter's doctors say about her health issues? What treatment is she under for the goitre?

You clearly are well acquainted with thyroid issues; for those who aren't, here's a simple explainer:

http://www.time.com/time/magazine/article/0,9171,760036,00.html

Was your daughter treated surgically? Does she take daily medicine for her thyroid? Were you given a list of things to watch for as she grew older?

Here is some information on polycystic ovary syndrome, what causes it and the symptoms:

http://www.4woman.gov/faq/pcos.htm#a

Here's a paragraph from that page on possible causes:

"The cause of PCOS is unknown. Most researchers think that more than one factor could play a role in developing PCOS. Genes are thought to be one factor. Women with PCOS tend to have a mother or sister with PCOS. Researchers also think insulin could be linked to PCOS. Insulin is a hormone that controls the change of sugar, starches, and other food into energy for the body to use or store. For many women with PCOS, their bodies have problems using insulin so that too much insulin is in the body. Excess insulin appears to increase production of androgen. This hormone is made in fat cells, the ovaries, and the adrenal gland. Levels of androgen that are higher than normal can lead to acne, excessive hair growth, weight gain, and problems with ovulation."

It's possible that the two are linked; it's also possible that the PCOS is causing your daughter's weight gain.

Here's a Cedars-Sinai article on MRIs of the pituitary gland. It's done with contrast dye, and gives doctors a view of any abnormal growths, infections or other problems:

http://www.cedars-sinai.edu/11089.html

Does your daughter have her own gynecologist yet, and does that gynecologist know about her thyroid issues? It might be good to investigate further the PSO connection to weight gain, and make sure the thyroid doctor and the gynecologist are talking to one another. See what they recommend, or ask for a specialist on issues of pituitary and growth hormone.

Best of luck to you and your daughter. Hormone issues are complicated; she's lucky she has you on her side!