Thyroid Profile Free Blood
What is this test?
This profile test measures the levels of both Free Thyroxine FT-4 and Free Triiodothyronine FT-3 in the blood and it also includes Thyroid Stimulating Hormone TSH test.
What is Thyroid Stimulating Hormone?
Thyroid Stimulating Hormone (TSH) is a pituitary hormone that stimulates the thyroid gland to produce triiodothyronine (T3) and thyroxine (T4) hormones. These hormones help to control the rate at which energy is used in almost every tissue in the body.
What are T3 and T4?
Thyroxine (T4) and Triiodothyronine (T3) which are secreted into the blood binds reversibly to the transport proteins like thyroxine-binding globulin (TBG), thyroxine binding prealbumin (TBPA), and albumin. Remaining unbound T4 and T3 circulates freely in blood and used by the body. This freely circulating Thyroxine (T4) and Triiodothyronine (T3) are known as Free Thyroxine FT-4 and Free triiodothyronine FT-3.
Why this test is performed?
The doctor may ask to get this test done if the patient exhibits symptoms such as unexplained weight loss or weight gain, fatigue, weakness, or difficulty in concentrating. In some cases, this test is performed to find out the effectiveness of the treatment. If a patient is on the treatment of artificial thyroid hormones then the doctor prefers this test to evaluate and to check the thyroid hormone levels in the body. This helps the doctor to rule out the patient’s disease condition.
Precautions:
Drugs like amiodarone, thiourea, lithium, phenylbutazone, sulfonamides, and birth control pills may change the levels of Free Thyroxine FT4 in the blood. Drugs like carbimazole, methimazole may affect the levels of TSH in blood. So, inform your doctor prior to the test if you are on these medications.
During pregnancy, FT3, FT4 levels may be abnormal and it is very common, though you can keep track of it and consult your doctor.
Pathology test parameters:
The Thyroid Profile Free test has the following components i.e:- Free Thyroxine T4, Free Triiodothyronine T3, and Thyroid Stimulating Hormone TSH.
Test Preparation
Inform your doctor if you are on any medications, have any allergies or underlying medical conditions before your Thyroid Profile Free Blood. Your doctor will give specific instructions depending on your condition on how to prepare for Thyroid Profile Free Blood.
There are no specific preparations required for the Thyroid Profile Free test.
Understanding your test results
If the test results are in normal range then the thyroid gland is functioning normally and may not need further medical intervention.
In the case of increased FT3 and FT4 levels in the blood than the normal range then it may be due to transient hyperthyroidism, Hashimoto's thyroiditis (an auto-immune disorder where the immune system of own body attacks the thyroid gland and decreases the production of hormones that are required for the body), Grave’s disease (an immune system disorder which results in the overproduction of thyroid hormones), subacute thyroiditis (acute inflammation of the thyroid gland), toxic adenoma (increased hormone production from single large nodule/lump in the thyroid gland), toxic multinodular goiter, thyroid cancer, increased production of thyroid stimulating hormone
If the levels of FT4 and FT3 are less than the normal range then it may be due to hypothyroidism, previous treatment of hyperthyroidism, subacute thyroiditis (acute inflammation of the thyroid gland), neck radiotherapy before the test, iodine deficiency or more, pituitary dysfunction, idiopathic myxedema (severe hypothyroidism), starvation, long-term illness, or euthyroid sick syndrome, etc
If TSH levels alone increased and FT4, FT3 levels are within the range then it may be due to mild hypothyroidism.
In case of reduced levels of TSH, it may indicate hyperthyroidism.
If all the three TSH, FT4, and FT3 levels are low then it may be due to nonthyroidal illness or pituitary hypothyroidism.
| Gender | Age groups | Value |
| FEMALE | All age groups | 1.8 - 5.4mcg/dl |