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Thyroxine - Total

Thyroxine - Total

For men & women
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Thyroxine (T4) Total test measures the thyroxine hormone in the blood. Thyroxine is produced by the thyroid gland, and plays a vital role in metabolism and growth. T4 circulates in the blood in two forms, free and bound form (bound with other proteins).
The T4 Total test is done to diagnose any suspected thyroid disease and to monitor treatment efficacy in patients having thyroid disease.
Excessive amounts of T4 in the blood result in symptoms associated with hyperthyroidism like weight loss and increased heart rate. Insufficient amounts of T4 leads to hypothyroidism and causes weight gain and dry skin.
Thyroid disorders are common (especially in women) but are treatable with medication and some dietary changes.



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What does Thyroxine - Total measure?

Thyroxine (T4) Total test measures the total levels (both free and bound forms) of Thyroxine hormone (T4) in the blood.

The thyroid gland secretes the following hormones:

  • Triiodothyronine (T3)

  • Thyroxine (T4)

Thyroid Stimulating Hormone (TSH), also called Thyrotropin is a hormone secreted into the blood by the pituitary gland (a gland present in the brain). It directs the thyroid gland to produce and release the thyroid hormones (T3 & T4) into your blood. The iodine from the food stimulates the thyroid gland to make the thyroid hormones.

The thyroid hormones regulate growth and metabolism. If the thyroid gland produces very high amounts of these hormones (T3 and T4), symptoms of weight loss, rapid heartbeat, tremors, sweating, anxiety, increased sensitivity towards heat, etc occurs. This is known as Hyperthyroidism.

The decreased production of thyroid hormones (T3 and T4) results in Hypothyroidism which may lead to 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 thyroid hormones (T3 & T4) from the thyroid gland and vice-versa.

T4 hormone constitutes about 90% of thyroid hormones and circulates in the blood in two forms:

1) Bound form - It is bound to the proteins present in blood and this prevents it from entering the body tissues. The three main proteins in the blood that the T4 hormone is bound to are albumin, transthyretin and Thyroxine-binding globulin (TBG). TBG is 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.

Hence, the T4 hormone can be measured as Free T4 or Total T4. The total T4 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.

While the total T4 test is a useful indicator of T4 levels in the presence of normal binding proteins, it is not useful when levels of binding proteins are increased or decreased. For example, increased total T4 levels can be seen despite normal levels of free T4 levels and normal thyroid function due to an increase in thyroxine-binding proteins.

Thyroxine (T4) Total test is also done as a part of the Thyroid profile Total test which includes two more tests: Thyroid Stimulating Hormone (TSH) and Triiodothyronine (T3) Total.

FAQs related to Thyroxine - Total

Inform the doctor about the medications you may be taking. No other specific preparations are usually required before this test.
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.
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.
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.
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.
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.
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.
Your doctor may order the following tests: Thyroid stimulating hormone (TSH) test, Thyroxine (T4) Free hormone test, Thyroid Hormone Binding Globulin (THBG) and Thyroid profile.
Content created by
Written by:
Dr. Lipika Khurana
BDS, PGDHHM
Reviewed by:
Dr. Swati Gupta (Anand)
MBBS, MD Lab Medicine
Want to know moreRead our editorial policy
Last Updated15th Jul 2025

Thyroxine - Total test price for other cities

Price inAhmedabadRs. 150
Price inAllahabadRs. 189
Price inBangaloreRs. 189
Price inBhopalRs. 189
Price inChandigarhRs. 189

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Thyroxine - Total