Thyroid Profile Free
What is Thyroid Profile Free?
The Thyroid Profile Free is a group of tests that are done together to detect or diagnose the thyroid diseases. It measures the levels of following three hormones present in free form in the blood: Thyroid Stimulating Hormone (TSH) ,Thyroxine (T4) - Free and Triiodothyronine (T3) - Free.
Note : On the day of test, those who are on thyroid medications, should take them in the same time and dosage as prescribed by the doctor. It should not be held for the test.
Why is Thyroid Profile Free done?
To diagnose any suspected thyroid disease (Hypothyroidism or Hyperthyroidism)
To monitor the patient’s response to thyroid diseases treatment
To investigate the cause of infertility
What does Thyroid Profile Free Measure?
The Thyroid Profile Free Test measures the levels of the following three hormones in the blood:
Thyroid Stimulating Hormone (TSH)
Thyroxine (T4) - Free
TriIodothyronine (T3) - Free
The thyroid gland (a small, butterfly-shaped gland located in front of the neck) secretes the following hormones:
Thyroid Stimulating Hormone (TSH) is a hormone secreted into the blood by Pituitary gland (a gland present in the brain). It directs thyroid gland to produce and release the thyroid hormones (T3 & T4) into the blood. The iodine from the food stimulates the thyroid gland to make the thyroid hormones.
The thyroid hormones regulates the growth and metabolism of the body. If the thyroid gland produces very high amounts of these hormones (T3 and T4), you may experience symptoms of weight loss, rapid heartbeat, tremors, sweating, anxiety, increased sensitivity towards heat, etc. and this is known as Hyperthyroidism.
The decreased production of thyroid hormones (T3 and T4) results in Hypothyroidism which may cause weight gain, fatigue, slow heart rate, increased sensitivity towards cold, depression, dry and thin hair, etc.
There is a feedback system in the body to maintain stable amounts of the thyroid hormones (T3 and T4) in the blood. When the levels of thyroid hormones decrease, the pituitary gland is stimulated to release TSH. High TSH in turn increases the release of T3 and T4 hormones from the thyroid gland and vice-versa.
T3 and T4 circulate in the blood in two forms:
1) Bound form - It is bound to proteins present in blood and this prevents it from entering the body tissues. The three main proteins in the blood that the thyroid hormones are bound to are albumin, transthyretin and Thyroxine-binding globulin (TBG), also called Thyroid hormone Binding Globulin (THBG).
2) Free form - It enters the body tissues where it is needed.
The total T3 or total T4 includes both the bound and the free forms circulating within the blood. Hence, thyroid hormones can be measured as Free T3, Total T3, Free T4 and Total T4.
The Thyroid Profile Free Test measures the free forms of T3 and T4 i.e. FT3 and FT4 along with TSH.
Interpreting Thyroid Profile Free results
Low T4 and T3 along with a high TSH level indicates hypothyroidism. The most common cause of hypothyroidism is Hashimoto thyroiditis
High T4 and T3 along with low TSH indicate hyperthyroidism. The most common cause of hyperthyroidism is Graves’ disease
Normal thyroxine T4 and T3 along with high TSH usually indicates mild or subclinical hypothyroidism
Normal T3 and T4 along with low TSH indicates mild or subclinical hyperthyroidism
Note: TSH levels show circadian variation (fluctuates during the 24-hour cycle), reaching peak levels between 2 - 4 am and are at low levels between 6-10 pm.
Tests Included (3 tests)
- Thyroid Stimulating Hormone, Ultrasensitive
- Thyroxine - Free