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Dr. Shreya Gupta

BDS, MDS - Oral and Maxillofacial Pathology

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Dr. Ashish Ranjan

MBBS, MD (Pharmacology)

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Triiodothyronine Total

(T3)

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You need to provide

Blood

This test is for

Male, Female

Test Preparation

No special preparation required

Overview

What is T3?

The Triiodothyronine (T3) Total test is used to measure Triiodothyronine (T3) hormone in the blood. T3 hormone is secreted by the thyroid gland. It is essential for growth and metabolism.

The test is performed to help evaluate thyroid gland function, diagnose thyroid disease, including hyperthyroidism and hypothyroidism. It also helps monitor treatment efficacy in patients with thyroid disease.

A high T3 level may indicate hyperthyroidism, symptoms like weight loss, rapid heartbeat, tremors, anxiety, and increased sensitivity to heat. A decreased production of T3 hormone may be indicative of hypothyroidism which may cause symptoms like weight gain, fatigue, increased sensitivity to cold, and slow heart rate.

The T3 levels can be managed by taking medication and possibly making a few dietary and lifestyle changes.

Why is T3 done?

To diagnose thyroid diseases (Hypothyroidism or Hyperthyroidism)
To monitor treatment in patients with thyroid diseases

What does T3 Measure?

Triiodothyronine (T3) Total Test measures the total levels (both free and bound forms) of Triiodothyronine (T3) hormone in the blood.

The thyroid gland secretes the following hormones:

Triiodothyronine (T3)
Thyroxine (T4)

Thyroid Stimulating Hormone (TSH) is a hormone secreted into the blood by a gland present in the brain (Pituitary gland) and it tells your thyroid gland to make and release the thyroid hormones (T3 & T4) into your blood. The thyroid gland uses iodine from food to make the thyroid hormones.

The thyroid hormones are essential for growth and metabolism. 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 to heat etc. and this is known as Hyperthyroidism.

Also, the decreased production of thyroid hormones (T3 and T4) results in Hypothyroidism which may cause symptoms like weight gain, fatigue, slow heart rate, increased sensitivity to 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 thyroid hormone levels decrease, the pituitary gland is stimulated to release TSH. This high TSH in turn leads to the release of more thyroid hormones (T3 & T4) from the thyroid gland and vice-versa.

Majority of the T3 hormone is formed from T4 hormone and a smaller fraction is produced directly by the thyroid gland. T3 hormone circulates in the blood in two forms:

1) Bound form - It is bound to proteins present in blood and this prevents it from entering body tissues. The two main proteins in the blood that the T3 hormone is bound to are albumin and Thyroxine-binding globulin (TBG), also called Thyroid hormone Binding Globulin (THBG).

2) Free form - It enters the body tissues where it is needed and this is the active form. Free Triiodothyronine (FT3) constitutes only 0.3% of the total T3 hormone.

The total T3 includes both bound and free forms circulating in the blood and can be affected by the amount of protein available in the blood to bind to them. The T3 hormone can be measured as Free T3 or Total T3. Triiodothyronine (T3) Total Test measures the total levels (both free and bound forms) of Triiodothyronine (T3) hormone in the blood and is usually done as a part of the Thyroid Profile Total test which includes two more tests: Thyroid Stimulating Hormone (TSH) and Thyroxine Total (T4) hormone.

Interpreting T3 results

Interpretations

T3 (Triiodothyronine), Total Reference Range(s)


	<1 Month	Not established
	1-23 Months	117-239 ng/dL
	2-12 Years	105-207 ng/dL
	13-20 Years	86-192 ng/dL
	>20 Years	76-181 ng/dL

Answers to Patient Concerns & Frequently Asked Questions (FAQs) about T3

Frequently Asked Questions about Triiodothyronine Total

Q. What are the symptoms of Hyperthyroidism?

Symptoms of Hyperthyroidism include: Rapid heartbeat (tachycardia) — commonly more than 100 beats/minute — irregular heartbeat (arrhythmia) or pounding of your heart (palpitations), sudden weight loss, nervousness, anxiety, irritability, tremor (usually a fine trembling in your hands and fingers), changes in menstrual patterns, increased sensitivity towards heat, changes in bowel patterns (especially more frequent bowel movements), an enlarged thyroid gland (goiter) which may appear as a swelling at the base of your neck, increased appetite, sweating, fatigue, muscle weakness, sleep disturbances, skin thinning, fine and brittle hair.

Q. What is Hypothyroidism?

Hypothyroidism, also called underactive thyroid or low thyroid is a condition in which the thyroid gland does not produce enough thyroid hormones. It can be commonly caused by intake of low iodine diet or Hashimoto's thyroiditis (an autoimmune disease). Less common causes include previous treatment with radioactive iodine, injury to the pituitary gland which secretes TSH, intake of certain medicines, previous thyroid surgery, or a lack of a functioning thyroid gland at birth.

Q. What are the symptoms of Hypothyroidism?

Hypothyroidism can cause symptoms such as tiredness (fatigue), hoarseness, constipation, feeling cold, dry skin, dry and thin hair, puffy face, weight gain, and muscle weakness. Along with that, one may experience decreased sweating, depression, slowed heart rate, increased blood cholesterol levels, pain, and stiffness in your joints, impaired memory, problems of infertility or menstrual changes, muscle stiffness, aches, and tenderness.

Q. Is there any risk associated with this test?

There is no risk associated with the test. However, since this test involves a needle prick to withdraw the blood sample, in very rare cases, a patient may experience increased bleeding, hematoma formation (blood collection under the skin), bruising or infection at the site of needle prick.

Q. How can hyperthyroidism affect a pregnant woman and her baby?

An untreated hyperthyroidism during pregnancy can lead to miscarriage, premature birth, low birth weight of the baby, preeclampsia (a very high rise in blood pressure in late pregnancy), thyroid storm (a sudden, severe worsening of symptoms of hyperthyroidism) and congestive heart failure.

Q. How can hypothyroidism affect a pregnant woman and her baby?

An untreated hypothyroidism during pregnancy can cause preeclampsia (a very high rise in blood pressure in late pregnancy), anemia, miscarriage, low birth weight of the baby, stillbirth (death or loss of a baby before or during delivery) and rarely, congestive heart failure. These problems are noticed mostly as a result of severe hypothyroidism. The mother’s thyroid hormones play an important role in the development of the baby’s brain and nervous system. Untreated hypothyroidism, especially during the first trimester can cause low IQ and can hinder the baby’s normal development.

Q. Is there any preparation required before the thyroid blood test?

No special preparation is required for this test. Inform the doctor about the medications you are taking as some medications like Corticosteroids, estrogen, progesterone, birth control pills, Lithium, Amiodarone etc. might interfere with the test results. A recent X-ray with iodine dye (contrast) or test using radioactive materials may also affect the results.

Q. What tests your doctor may order to detect the thyroid disease in addition to T3 Total test?

Your doctor may order the following tests: Thyroid stimulating hormone (TSH) test, T3 Free hormone test and Thyroid profile.

Q. What is Hyperthyroidism?

Hyperthyroidism is a condition in which the thyroid gland is overactive and there is an increased production of thyroid hormones by the thyroid gland. Causes of Hyperthyroidism include Graves’ disease, multinodular goiter, thyroid nodules, toxic adenoma, inflammation of the thyroid, eating too much iodine, and too much synthetic thyroid hormone. Diagnosis of this condition can help to relieve the symptoms and prevent long-term complications.

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About Thyrocare Technologies Limited

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Thyrocare Technologies Limited is India's first and most advanced Totally Automated Laboratory having its strong presence in more than 2000 cities / towns in India and internationally. Thyrocare is India's first fully automated diagnostic laboratory with a focus on providing quality at affordable costs to laboratories and hospitals in India and other countries. Thyrocare operates with a Centralized Processing Laboratory (CPL) in Mumbai - India for esoteric tests; and Regional Processing...

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User Reviews

Vivek Shukla

Very nice experience. Highly recommended.

Girish K Kulkarni

Awesome experience. Pathology test was never so easy.

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