I am concerned, with the continuing weight gain along with the depression, that it is possible your DD is not receiving adequate treatment for her hypothyroid. It is relatively common in America for doctors to undertreat hypothyroid. If you are fully confident she is being adequately treated, then of course disregard the suggestions below.
Perhaps you are already doing this: get photocopies of your DD's labwork. Learn all you can about her particular type of thyroid disorder, and follow the labwork carefully.
Do you know whether your DD has had thyroid antibodies tested? This is important to check. There are three different antibody tests. Autoimmune hypothyroid can be slightly trickier to treat than garden-variety thyroid failure.
If your DD does have an autoimmune thyroid disorder, like Hashimoto's disease, you may wish to have her tested for celiac disease. Autoimmune thyroid disorders are several times more common in young celiacs than among young non-celiacs. Celiacs (not to say your DD is one) who get on a gluten-free diet at an early age have reduced risk of acquiring additional autoimmune diseases. And, for those who are gluten-sensitive, the special diet has been shown in several research studies to reduce thyroid autoantibodies. Which is a good thing.
Many docs base treatment of hypothyroid on TSH alone, which is less helpful than regular free T3 & free T4
thyroid hormone testing. When you examine the lab printouts, check to see that your DD's levels for the free hormones are at least mid-range. If they are at the lower end of the range, she may still be symptomatic. There are other T3 & T4 tests, but the free hormone tests are most helpful.
During adolescence there is increased demand for thyroid hormone due to growth & development. For girls, there is an extra glitch that gets thrown in, and that is that adolescent females tend to run extremely high levels of estrogen. The estrogen can bind up the thyroid hormone (whether from pills or homemade
) & make it less easy for the body to use.
Some people find that thyroid meds other than Synthroid are more helpful for them. These are typically meds that include some of the active thyroid hormone, T3. Armour thyroid contains both T3 & T4. It is dessicated from the gland of pigs, and has a huge following -- many of these people who did not do best on T4 meds like Synthroid. The other main T3 med is called Cytomel, a synthetic but bioidentical T3. I myself take T3 in a slow -release form, specially compounded, and have found that it has been a very helpful addition to my T4 med.
It's possible your DD's depression is due to her thyroid problem. Or, it could be simpler, related to weight issues, popularity, etc. Assuming this is not a deep, severe depression, and if you are not interested in antidepressant meds, I recommend you research & consider 2 things. The first is regular, mild aerobic exercise. Doesn't have to be terribly vigorous. Even a walk can kick in endorphins & lift mood. Numerous studies have shown mild exercise is as effective as SSRIs. So, I recommend this to your DD as a life-long habit. The PE/gym is great, but why not go for a walk, or take out your bike for a spin on the weekend. Having a friend to chat with on walks -- or a pet to exercise, can help ease the boredom of the regimen. Ditto for iPods.
The other thing I recommend you research & possibly try for mild to moderate depression, is EPA fish oil concentrate. One to Two grams per day of the EPA fraction (check the label of the supplement). I recommend the molecularly- distilled EPA concentrates, like Carlson's, Nordic Naturals & Omega Joy for purity (you don't have to worry about mercury & PCBs), as well as for taste. The distillation takes out much of the fishy flavor.
The best EPA concentrates are not cheap, however, there has been lots of good scientific research on EPA concentrate (Pub Med is great for research studies) & it has proven time & again to be helpful for depression. It's also great for the heart, soft skin, lots of good side benefits. However, EPA cannot be used by people with bleeding disorders like hemophilia, or people who are on blood-thinner medication. We've used EPA concentrate in our family for over 6 yrs. & find it indispensible.