TSH is thyroid stimulating hormone, which is made by the pituitary gland to regulate production of thyroid hormones. If levels of these hormones fall, the pituitary releases TSH to simulate the thyroid gland to produce more. High levels of TSH usually indicate underactivity of the thyroid (hypothyroidism).
Symptoms of hypothyroidism often develop gradually, sometimes over the course of several years. Women age 50 and older are at greater risk than men, although teenagers, children and even infants can be affected. When symptoms occur, they can include increasing fatigue and weakness, often with unintentional weight gain. Skin can become dry, rough and pale, with hair loss and dry, brittle nails. Other frequent problems are sensitivity to cold, muscle or joint aches, constipation, depression, irritability, memory loss, abnormal menstrual cycles with heavy blood flow, and decreased sex drive.
Use of sea salt or lack of iodine does not cause elevated TSH. Signs of iodine deficiency frequently include an enlarged thyroid gland (goiter), and weight gain, as well as the other symptoms of hypothyroidism. (Iodine deficiency is very rare in the U.S., even among people who avoid iodized salt; there are plenty of other dietary sources, including eggs and dairy products.)
In all likelihood your friend is hypothyroid. The most common cause is an autoimmune condition known as Hashimoto's thyroiditis. This disorder is more common in women and in those with a family history of autoimmune diseases. It involves immune-related inflammation of the gland, which interferes with production of thyroid hormones. The exact cause and triggers of Hashimoto's are unknown.
The best course of action for your friend is to have a medical workup. If her problem is hypothyroidism, most conventional doctors prescribe the drug Synthroid or another preparation of levothyroxine, a synthetic analog of the thyroid hormone T4; dosage is based on symptoms and TSH level. I prefer combinations of both thyroid hormones, T3 AND T4, which often work better and may also have a more positive effect on mood than T4 alone.
Andrew Weil, M.D.