A:
TSH stands for thyroid stimulating hormone. It’s a simple blood test. Doctors order a TSH blood test if a person:
- Has symptoms that suggest a thyroid problem, or
- Is taking thyroid medication, such as Synthroid, to see if the dose is correct.
Thyroid stimulating hormone is made by the pituitary gland in the brain, then released into the blood stream. When TSH reaches the thyroid gland, it stimulates the gland to produce more thyroid hormone.
If the blood levels of thyroid hormones (T3 and T4) drop below the normal range, the TSH level rises. If there is too much thyroid hormone in the blood, the TSH level gets very low.
An abnormally high TSH level almost always indicates an underactive thyroid gland (hypothyroidism). A very low TSH level usually means there is too much thyroid hormone in the blood (hyperthyroidism).
There are some rare causes of an underactive thyroid gland with a low TSH. For example, if a person has a diseased pituitary gland.
TSH is a more sensitive indicator of thyroid function or correct thyroid dose than T3 or T4. Similar to you, many people have a high TSH with T3 and T4 that fall into the normal range. Usually, the T3 and T4 will be at the low end of normal when the TSH is high.
Here are some reasons why your TSH might be rising:
- Most people take a generic version of levo-thyroxine (Synthroid). You might be taking levo-thyroxine made by a different company than the pills you took before.
- Have you started any new supplements or medications? Iron, other supplements and certain medications can interfere with absorption of levo-thyroxine. Check with your pharmacist about drug interactions.
- Certain foods can lower the absorption of levo-thyroxine. Maybe you started taking your thyroids pills with meals. It’s best to take your pills one hour before eating.
You didn’t mention your actual TSH value. The reports from most labs show a normal range of 0.45 to 4.5. But many thyroid experts use a normal range of 0.3 to 3.0.
You are having symptoms of hypothyroidism and your TSH is rising. So you do want to make an adjustment. If none of the above reasons for a rising TSH applies to you, you likely need a higher dose of levo-thyroxine.
