What is a Thyroid Function Test? How is it done? What are the tests to check your thyroid gland? Everything you should know, in this post and of course our doctors are always there to help you. Just fill in your details in the form above and we will answer all your questions for FREE!
What are the thyroid function tests?
This test measures the series of blood tests of the thyroid gland. It is used to measure the amount of thyroid-stimulating hormones (TSH), thyroxine (T4) and triiodothyronine (T3) in the blood.
Also Read: Free T3 Test
What is TSH?
TSH stands for thyroid-stimulating hormone also known as thyrotropin. It is a hormone that controls the function of the thyroid gland. It acts as a messenger to the thyroid gland. The pituitary gland produces TSH. It stimulates the production of three thyroid hormones:
- T4 (thyroxine)
- T3 (triiodothyronine)
- Calcitonin
T4:
It is a type of thyroid hormone, also known as thyroxine. It regulates the metabolism. Thyroxine plays an important role in muscle function, digestion, and bone development. There are two forms of the T4 hormone in the blood:
- Free T4
- Bound T4
Normal levels of total T4 in adults: 5-12 mcg/dl
T3:
It is a hormone called triiodothyronine (T3). The T3 test is done to diagnose the thyroid problem called hyperthyroidism. There are two forms of the T3 hormone:
- Free T3
- Bound T3
What is the function of the thyroid gland?
- It regulates the production of thyroid hormones from the thyroid gland.
- It regulates the metabolism of the body.
- It regulates the body temperature.
- Thyroid hormones help in controlling weight, muscle strength, and even mood.
- It helps in growth and brain development in children.
What are the normal TSH levels?
These are the expected levels of TSH according to age.
- Infants – 5 days old: 0.7 – 15.2 ulU/mL
- Infants 6 to 90 days old: 0.7 – 11.0 ulU/mL
- Babies 4 to 12 months old: 0.73 – 8.35 ulU/mL
- Children up to 6 years old: 0.7 – 5.97 uIU/mL
- Children 7 to 11 years old: 0.6 – 4.84 uIU/mL
- Teenagers 12 to 20 years old: 0.51 – 4.3 uIU/mL
- Adults 21 to 99 years old: 0.27 – 4.2 uIU/mL
What are normal TSH levels during pregnancy?
The TSH levels fluctuate throughout the pregnancy. This test is essential for people who are pregnant to have a normal amount of TSH and thyroid hormones to ensure the healthy development of their babies.
The normal TSH levels during pregnancy include:
- First trimester: 0.18 – 2.99 uIU/mL
- Second trimester: 0.11 – 3.98 uIU/mL
- Third trimester: 0.48 – 4.71 uIU/mL
Why would I need a thyroid function test?
This test is done to check the various conditions :
- To monitor and diagnose the treatment of a thyroid disorder.
- To help in evaluating pituitary gland function.
- This test tells if you have hyperthyroidism or hypothyroidism.
- To monitor the goitre (enlargement of the thyroid gland).
- To evaluate a thyroid nodule.
What are the causes of hypothyroidism?
- Hashimoto’s thyroiditis
- Thyroiditis
- Previous thyroid treatment
- Congenital hypothyroidism
What are the symptoms of hypothyroidism?
The increased levels of TSH indicate hypothyroidism. When the thyroid gland does not produce an adequate amount of hormones, then the pituitary gland produces more TSH to compensate. The thyroid gland produces too little T4 and slows down the metabolism.
The symptoms of hypothyroidism may include:
- Fatigue
- Weight gain
- Dry skin
- Increased sensitivity to cold weather
- Hairfall, thinning of hair
- Swelling of the face and neck
- Irregular periods
- Fertility problems
- Constipation
What are the causes of hyperthyroidism?
- Graves’ disease
- Thyroid nodules
- Excessive iodine intake
What are the symptoms of hyperthyroidism?
The low levels of TSH indicate hyperthyroidism. It is also known as an overactive thyroid. The thyroid gland produces too much T4 (thyroxine) and speeds up the metabolism. If the thyroid gland is secreting more levels of hormones that are high, then the pituitary gland produces less TSH.
The symptoms of hyperthyroidism may include:
- Irregular heart rate
- Weight loss
- Muscle weakness
- Mood changes
- Sleep disturbed
- Irritability or nervousness
- Frequent bowel movements or loose motion
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For more information, you can visit Healthline and Testing.com.
