Thyroid Stimulating Hormone Test (TSH Thyroid Test)

​​Thyroid stimulating hormone test (TSH thyroid test)

It is a simple blood test which measures TSH (thyroid stimulating hormone) levels in blood. Thyroid stimulating hormone is an important hormone secreted by pituitary gland (in brain) into the bloodstream. Abnormal levels of this hormone can have a profound effect on various organs and their functioning.

TSH is also called as thyrotrophin. After its release into blood stream, it binds to receptors on the thyroid gland (butterfly shaped gland, present at the bottom of your throat). The thyroid gland then secretes optimum amount of thyroxine (T4) and triiodothyronine (T3) into bloodstream. If optimum amount of these two hormones is reached, they send negative feedback to pituitary to stop secreting TSH.

These hormones have an effect on various body functions such as brain, heart, metabolism, bone, digestion, temperature regulation, mood, muscle strength etc.

A high level of TSH (with/without low T4 and T3) results in hypothyroidism (underactive thyroid gland). It presents as: weight gain, constipation, hair loss, dry skin, slow heart rate, fatigue

Low levels of TSH (with /without high T4 and T3) results in hyperthyroidism (overactive thyroid gland). It presents as: weight loss, rapid heart rate, anxiety, bulging eyes, insomnia, hand tremors.

Why is TSH thyroid test prescribed?

Your healthcare provider may ask for this test in following situations:

• As a part of routine health check up to look for thyroid gland functioning
• If there are symptoms of hyperthyroidism or hypothyroidism as mentioned previously
• To monitor response of treatment of above-mentioned conditions
• Detect abnormal levels during pregnancy which can have adverse effect on foetus.

What are the components of thyroid stimulating hormone test?

An abnormal TSH report does not tell the cause of this abnormality. For this further test are required like T4, T3, which together is called as Thyroid Function Test (TFT) or Free T3 & Free T4 (Free TFT).

Procedure and prerequisites

The sample for thyroid stimulating hormone test is taken from blood by inserting a small needle into vein of your arm. A small amount of blood is then collected in test tube or vial. You may feel little pain due to needle prick. You may resume your daily activities immediately. No particular preparation is needed for this test. Certain medications can have an effect on thyroid function so consult your doctor before taking this test

Reference range

Normal range-0.5-5.0 milli-international units per litre (mIU/L)

Reference range may vary from lab to lab.