What are the causes of slightly elevated thyroid level?

There are many reasons a thyroid level may become slightly elevated. Getting to the right reason, as well as understanding exactly which thyroid level is elevated, is key to getting your levels back in check. Depending on the cause of the elevation, catching your thyroid problems when your levels are only slightly off will let you get treatment before the symptoms become more severe.

Thyroid Levels Explained

If your doctor suspects that you have a thyroid problem, he or she will use a blood test to check three different thyroid hormone levels: TSH, T4 and T3. TSH is thyroid stimulating hormone and is produced by your pituitary gland. TSH prompts your thyroid to produce T4 (thyroxine), which is then converted to T3 (triiodothyronine). According to the Thyroid Foundation of Canada, T4 is actually an inactive hormone; the final T3 product actually does the "work" of the thyroid, which is likened to the cruise control in your car. Your thyroid controls your metabolism, so in effect it can speed up or slow down all of your body's systems.

Elevated TSH Levels

Slightly elevated TSH levels indicate that the thyroid is not producing enough thyroid hormone, a condition also known as hypothyroidism or underactive thyroid. (See Resources section for normal range.) Since TSH stimulates the thyroid, excess TSH indicates that the pituitary gland is trying to get the thyroid to become more active. Causes for elevated TSH include Hashimoto's Thyroiditis, an autoimmune condition in which the body's own immune system attacks the thyroid; pregnancy; and pituitary gland disorders. You may also develop elevated TSH levels after having radiation therapy, thyroid surgery, or if you have an iodine deficiency or are taking thyroid suppressing medication because of hyperthyroidism (overactive thyroid).

Elevated T4 and T3 Levels

Elevated T4 and T3 levels indicate that the thyroid is producing too much thyroid hormone (hyperthyroidism). According to the American Thyroid Association, T3 levels are the last thyroid level to become abnormal when there is a problem, so you may have an elevated T4 and normal T3 if you catch your condition early. The causes for elevated T4 and T3 levels include Graves' Disease, an autoimmune disease in which the thyroid is attacked and responds by becoming overactive; thyroiditis (inflammation or infection of the thyroid for reasons doctors do not understand); and thyroid nodules, which are growths on the thyroid.


Treatment depends on the cause of your thyroid level elevation. Elevated TSH is treated using thyroid hormone replacement medication. Elevated T4 and T3 levels are treated using thyroid suppressing medication or radioactive iodine therapy. Sometimes, thyroid nodules require surgery. If your elevated levels are caused by a temporary situation, like pregnancy or infection, they may return to normal without treatment.


It can take time to find the correct dosage of medication to treat your elevated thyroid levels. Your doctor will work with you to monitor your treatment.

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