Does not require fasting
Measurement in the laboratory
Includes 23 test results
159,00 €
Free thyroxine (T4-V) or tetraiodothyronine is a thyroid hormone
Thyroxine is a hormone secreted by the thyroid gland. If there is too little thyroxine in the body, the condition is called hypothyroidism. If the thyroxine level is high, the condition is called hyperthyroidism.
Free thyroxine T4-V
- Thyroxine is a hormone secreted by the thyroid gland.
- If there is too little thyroxine in the body, it is called hypothyroidism.
- If there is too much thyroxine, it is called hyperthyroidism.
- The thyroid gland affects the body’s metabolism.
Table of contents
Thyroxine is a hormone secreted by the thyroid gland. If there is too little thyroxine in the body, the condition is called hypothyroidism. If the thyroxine level is high, the condition is called hyperthyroidism.
Thyroxine T4
Thyroxine is one of the two important thyroid hormones. The thyroid regulates the entire body’s metabolism.
The thyroid is a gland weighing about 20 grams and it is located in the neck. Its overactivity or insufficiency may cause various symptoms in the body.
What is free thyroxine T4-V?
Thyroxine (or tetraiodothyronine) is one of the important thyroid hormones in addition to triiodothyronine. Thyroxine amounts to more than 80 per cent of the thyroid hormones in blood.
Free thyroxine is not bound to transporter proteins. Thyroxine is a derivative of the amino acid tyrosine. It contains four iodine atoms.
Most of the thyroxine circulating in the body is bound to transporter proteins. The total amount of T4 depends on the amount of transporter proteins.
The letter T in the lab test abbreviation T4-V refers to thyroxine. The four iodine atoms are indicated by the number 4 and the letter V stands for the Finnish word for “free”.
In hypothyroidism, the amount of thyroxine in the blood is lower than normal and in hyperthyroidism it is higher than normal.
In addition to the T4-V study, the amount of thyroid stimulating hormone (TSH) secreted by the pituitary gland should be analysed.
How can I order a thyroxine test?
You can order a free thyroxine (T4-V) test from Puhti’s online store here.
Through Puhti’s service, you can access laboratory tests without a referral, and if necessary, you can order a separate remote consultation with a doctor after the tests, for example, if there is suspicion of illness.
What are the reference values for free thyroxine S-T4-V?
The reference values for free thyroxine S-T4-V for all people are 9–19 pmol/l (picomoles per litre).
The reference values vary from laboratory to laboratory and according to the analysis method. Puhti samples are taken and analysed at the laboratories of Mehiläinen.
The analysis can be misrepresentative due to a rheumatoid factor, albumin binding abnormalities, heparin therapy and T4 antibodies.
High T4-V, free thyroxine
Free thyroxine may also be high due to reasons other than actual thyroid dysfunction. All of the following conditions and situations may cause free T4 to rise:
- Hyperthyroidism is diagnosed if other tests also suggest it and the patient develops symptoms indicative of it.
- Postpartum period may cause the values to rise. In this case the test should be repeated after some time so that the body has time to recover. The value may decrease on its own over time or the condition may develop into hyperthyroidism.
- Certain medications may increase the values.
- Diseases that involve an increase in free fatty acids may also increase the amount of free T4.
Low T4-V, free thyroxine
The amount of free T4 is decresed in hypothyroidism.
Why is free thyroxine T4V studied?
When examining hyperthyroidism or hypothyroidism, the amount of free thyroxine should be studied as its concentration is less affected by the amount of transporter proteins. This provides a more accurate picture of the function of the thyroid gland.
The overall level of thyroxine is more influenced by the amount of transporter proteins, which can be analysed with a separate test.
Free thyroxine should be studied if symptoms of thyroid dysfunction occur. Typical symptoms of hyperthyroidism include weight loss, rapid heartbeat and sweating. Typical symptoms of hypothyroidism are weight gain, slow pulse, fatigue and general poor condition.
Potential insufficiency in newborns is automatically checked as a standard procedure as failure to treat it can lead to serious health problems.
Determining the amount of free T4 is important, especially if other tests, such as TSH, are within the reference values or there are inconsistencies in the interpretation of their results.
- RECOMMENDED!Does not require fastingSampling between 6-10 a.m.Includes 25 test results169,00 €
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