What Do We Measure in a Thyroid Profile?

What do we Measure in a Thyroid Profile?

It is important to know that most of the T4 & T3 found in our blood are bound to a protein. But only the Freeform that is not bound, can carry out the functions in various organs. There are instances when the levels of these proteins can change in our blood. This can happen during pregnancy and in women taking birth control pills when the amount of these binding proteins increase. This results in the less available free form of T4 and T3 in the blood.

• Blood tests to measure thyroid hormone levels - A thyroid profile is done on a blood sample collected from a vein the arm. To see ifthe thyroid gland is overactive or underactive the drawn our blood sample will help in measurement of the following hormones - TSH- thyroid stimulating hormone- is the best Initial test to see the functioning of our thyroid gland. A low level of TSH indicates an overactive thyroid, that is, the gland is producing too much T4 and T3- This is called Hyperthyroidism

A high level of TSH means that the thyroid gland is not producing enough hormone, this is called Primary Hypothyroidism. Sometimes there is a problem in the pituitary gland, which can also lead to a low TSH. This is a Secondary Hypothyroidism.

• Free T4 - Is the most important test done to see the functioning of the thyroid gland. A high level is seen in Hyperthyroidism, while a low level is seen in Hypothyroidism.
• Free T3- It is usually only tested for Hyperthyroidism or to know its severity.

There are also some additional tests to check the health of the thyroid gland in certain conditions-

• Thyroid antibodies - is done when there is suspicion of autoimmune disease that is affecting the gland and the thyroid profileshows that there is a thyroid problem.
• Thyroglobulin- this is a protein produced by the thyroid gland cells as well as thyroid cancer cells. It is measured in people who are being treated for thyroid cancer.(2^✔ ✔Trusted Source
  Information About - Thyroid Function Tests
  
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Normal Values of a Thyroid Profile

1. TSH- 0.4 to 4 mU/L
2. Free T4- 9-25 picomoles/L
3. Free T3- 3.5- 7.8 picomoles/liter
4. Microsomal thyroid antibodies(TPO)- 0.0-5.0 IU/ml

Diagnosis of Thyroid Disease

• A high T4 and Low TSH indicates - Hyperthyroidism or overactive thyroid gland
• A low T4 and High TSH indicates - Hypothyroidism or underactive thyroid gland
• Subclinical Hypothyroidism - when TSH level is high or mildly high, but T4/T3 levels are normal
• Subclinical Hyperthyroidism- when TSH level is low or very low but T4/T3 levels are normal.

OVERT HYPERTHYROIDISM   

TSH LEVEL	THYROID HORMONES
<0.1 mIU/L or undetectable	Elevated T4 or T3
OVERT HYPOTHYROIDISM
>4.5 mIU/L	Low T4
SUBCLINICAL HYPERTHYROIDISM
<0.1 mIU/L	Normal T4 and T3
0.1–0.4 mIU/L	Normal T4 and T3
SUBCLINICAL HYPOTHYROIDISM
4.5–10.0 mIU/L	Normal T4
≥10 mIU/L	Normal T4

Table indicating the Thyroid Conditions &Various Levels of Thyroid Hormones(3^✔ ✔Trusted Source
Thyroid Dysfunction: Screening

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