TSH blood test or thyroid stimulating hormone blood test is a simple blood test. TSH is a hormone which stimulates the thyroid gland into secreting the thyroid hormones. TSH is formed by the pituitary gland, which is the gland located at the base of the brain. It is the main gland of the endocrine system. The pituitary gland tells the thyroid gland, to produce and release the hormone triiodothyronine which is more known as T3, and thyroxine hormone which is more called T4. The doctor will ask you to get this test done, if you are showing any abnormal signs of thyroid function. This test is also performed regularly by patients associated with abnormal thyroid function conditions like hyperthyroidism and hypothyroidism.
TSH test helps to measure the amount of thyroid stimulating hormone present in the blood. Given below are the details of this test, that will help you to prepare before the test, and understand the results.
Preparing for the Test
Fasting for this test is not required, as this blood test can be performed at any time of the day. However, the health care provider will ask to stop taking certain drugs which interfere with the test. Drugs like amiodarone, lithium, potassium iodide, prednisone, antithyroid medications, and dopamine can affect the test results.
How is the Test Performed?
The procedure of TSH blood test to detect any thyroid problems differs for both children and adults. For infants or children, a sharp tool called lancet is used to puncture the skin and allow the blood to come out. This blood will be collected in a small glass tube called pipette, or collected onto a test strip. The bandage is placed over the punctured skin, to stop any bleeding. For adults, the blood is drawn out of a vein, which is usually located inside the elbow or back of the hand. The health care provider will wrap an elastic band on the arm, before inserting the needle inside the vein. The elastic band will exert pressure on the site and make the vein swell with blood. The health care provider after drawing the blood in the needle, will collect it in an airtight vial, and remove the elastic band from your arm. Once the blood is collected, the needle is removed, and the punctured area will be covered to prevent bleeding.
Is the Test Painful?
The test is mildly uncomfortable, as while the needle is inserted the person feels moderate pain, or a pricking sensation. Later on, a throbbing sensation will be felt on the punctured site.
The normal TSH level value can differ from laboratory to laboratory. But, in general, the normal range is between 0.4 - 4.0 mIU/L. If a person without showing any symptoms of an underactive thyroid shows a value over 2.0 mIU/L, then it is possible that he/she might develop hypothyroidism in the future. This is perhaps an early stage of hypothyroidism. A person showing such results, should be closely monitored by the doctor. Show your doctor the reports, to discuss in detail about the TSH test results.
Abnormal Results Explained
Abnormal TSH blood level indicates a disorder. Given below, are the disorders associated with high or low TSH levels.
High TSH Levels
- The person has resistance of thyroid hormone.
- It means the patient has primary hypothyroidism. Hashimoto's thyroiditis is one of the most common types of primary hypothyroidism.
- The patient is going through the condition of TSH-dependent hyperthyroidism.
- A person who is exposed to mice, can also show above the normal TSH levels. These people are mostly lab workers or vet doctors.
- Cretinism is also a sign pointing to higher than normal TSH levels.
- Although uncommon, a pituitary gland tumor can release too much TSH.
- Elevated TSH levels also suggest that the patient who has been diagnosed with hypothyroidism (underactive thyroid gland) is not taking enough medicine.
Low TSH Levels
- This means that the person has a condition of hyperthyroidism.
- Due to some kind of damage, the pituitary gland is not releasing sufficient TSH. So, there is a deficiency of thyroid stimulating hormone.
- A person who is using certain medications like glucocorticoids, bexarotene, and dopamine agonists can also show lower than normal TSH levels.
- A pregnant woman may have low TSH levels in the first trimester.
- Excessive consumption of thyroid medicine for treatment of an underactive thyroid gland can lower TSH levels.
If you get an abnormal TSH blood test result, then consult your doctor. The treatment varies from individual to individual. The treatment suggested by your doctor will involve use of certain medicines that will help you maintain normal TSH level. Depending upon the condition, you may have to undergo follow-up tests (every two or three months). They will help monitor your TSH levels.
Disclaimer: This article is for informative purposes only and does not in any way attempt to replace the advice offered by an expert on the subject.