TFTs or Thyroid Function Tests are the tests by which the function of the thyroid gland is checked. These are blood tests and are conducted on patients to determine whether their thyroid gland is functioning properly or not.

What role does the thyroid gland play in the body?

The thyroid gland is a part of the endocrine system and is responsible for secreting the hormone thyroxine. The gland uses iodine to make the hormone. The release of thyroxine in turn is controlled by the TSH or thyroid stimulating hormone, secreted by the pituitary gland. Thyroxine is responsible for controlling the metabolism of the human body, how quickly sugar is made and used up in the body and how forcefully the heart squeezes.

When there is excess of thyroxine in the blood, the TSH reduces automatically. Thyroid disorders can occur with increased levels of TSH (hyperthyroidism), or reduced levels of TSH (hypothyroidism).

Are thyroid tests sufficient to determine thyroid disorders?

  • The most common type of TFT is the TSH testing. It has been found in a significant section of the population that TSH test might not be sufficient to determine whether the thyroid gland is properly functioning or not. TSH is just a measure of how well the pituitary and thyroid glands are communicating with one another. Testing of TSH alone might not be sufficient to judge the functioning of thyroid gland.
  • Sometimes TFTs can produce incongruent results. For example, raised level of thyroid hormones (TH) and non-suppressed TSH, or high levels of TSH and normal TH. In such cases, further investigations are deemed necessary.
  • TFTs may show different results in exceptional scenarios, for example, in pregnancy, under certain medications and non-thyroidal illnesses.
  • TSH levels can also vary under conditions like stress, fatigue and obesity, thus giving inappropriate results.

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