If you need to know which are the T4 reference ranges or you require more information about the role of T4 in the blood, you can visit normal T4 level in the blood
A T4 (Thyroxine) level in the blood above the normal range may be a sign of hyperthyroidism, a disease where the thyroid gland produces too much thyroid hormones.
T4 values should be studied along with the values of T3 hormone (Triiodothyronine) and TSH hormone (thyroid-stimulating hormone) for a better diagnosis.
There are two types of hyperthyroidism and it is important to study TSH values to discern them:
T4 blood values are usually given in µg/ml but sometimes you can see these values in nmol/l following the International System of Units (SI). In case your values are in nmol/l you can convert them using this tool:
Hyperthyroxinemia or high T4 blood levels mean:
T4 (thyroxine) values are very high and it may be the consequence of suffering from hyperthyroidism, a hyperfunction of thyroid gland.
If the TSH (thyroid-stimulating hormone) value is above the normal range is a sign of primary hyperthyroidism where there is a problem of the thyroid gland.
It can be advisable to study free T4 in the blood to get more information about the disorder.
When the T4 level in the blood is higher than normal, you may suffer from irritability and weight loss. You should visit your doctor or an endocrinologist to prescribe you a proper treatment.
There are some health circumstances or drugs than can raise your T4 level in the blood:
The following diseases may raise the T4 level in the blood:
There are some antithyroid drugs, such as carbimazole, that may reduce your T4 level in the blood. They should be used only under medical prescription.
Another possible treatment, if your doctor considers it appropriate, is thyroidectomy (surgical removal of all or part of the thyroid gland) following by oral synthetic T4 (Levothyroxine).
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The following values are considered to be above the normal range:
IMPORTANT: These levels are expressed in µg/dl. They are an example of a healthy man of about 45 years old with no known disease and not taking any medication. The ranges can be different depending on the laboratory or on your personal circumstances.
T4 | |||||||
|---|---|---|---|---|---|---|---|
| Marked hyperthyroxinemia | |||||||
| 12.1 µg/dl | 12.2 µg/dl | 12.3 µg/dl | 12.4 µg/dl | 12.5 µg/dl | 12.6 µg/dl | 12.7 µg/dl | 12.8 µg/dl |
| 12.9 µg/dl | 13 µg/dl | 13.1 µg/dl | 13.2 µg/dl | 13.3 µg/dl | 13.4 µg/dl | 13.5 µg/dl | 13.6 µg/dl |
| 13.7 µg/dl | 13.8 µg/dl | 13.9 µg/dl | 14 µg/dl | 14.1 µg/dl | 14.2 µg/dl | 14.3 µg/dl | 14.4 µg/dl |
| 14.5 µg/dl | 14.6 µg/dl | 14.7 µg/dl | 14.8 µg/dl | 14.9 µg/dl | 15 µg/dl | 15.1 µg/dl | 15.2 µg/dl |
| 15.3 µg/dl | 15.4 µg/dl | 15.5 µg/dl | 15.6 µg/dl | 15.7 µg/dl | 15.8 µg/dl | 15.9 µg/dl | 16 µg/dl |
| 16.1 µg/dl | 16.2 µg/dl | 16.3 µg/dl | 16.4 µg/dl | 16.5 µg/dl | 16.6 µg/dl | 16.7 µg/dl | 16.8 µg/dl |
| 16.9 µg/dl | 17 µg/dl | 17.1 µg/dl | 17.2 µg/dl | 17.3 µg/dl | 17.4 µg/dl | 17.5 µg/dl | 17.6 µg/dl |
| 17.7 µg/dl | 17.8 µg/dl | 17.9 µg/dl | 18 µg/dl | 18.1 µg/dl | 18.2 µg/dl | 18.3 µg/dl | 18.4 µg/dl |
| 18.5 µg/dl | 18.6 µg/dl | 18.7 µg/dl | 18.8 µg/dl | 18.9 µg/dl | 19 µg/dl | 19.1 µg/dl | 19.2 µg/dl |
| 19.3 µg/dl | 19.4 µg/dl | 19.5 µg/dl | 19.6 µg/dl | 19.7 µg/dl | 19.8 µg/dl | 19.9 µg/dl | 20 µg/dl |
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