FT4

fT4 - thyroxine test

FT4 test performed from the blood to determine the concentration of free thyroxine - the thyroid hormone. Free thyroxine (fT4) plays an important role in the regulation of metabolism, such as in the absorption of glucose.

Ft4 test what is it

The ft4 test is used to assess thyroid function. The work of the thyroid gland is controlled by the pituitary gland, which secretes the hormone thyrotropic hormone - TSH. It stimulates the thyroid gland to secrete the hormones fT4 thyroxine and fT3 triiodothyronine. Determination of the level of this hormone is necessary in the diagnosis of thyroid diseases.

fT4 high

The causes of elevated fT4 values are:

• Iodine-induced hyperthyroidism (earlier than fT3),
• early stages of Hashimoto's disease,
• treatment with high doses of thyroxine,

fT4 low

Reasons for lowered fT4 values:

• hypothyroidism,
• thyroiditis,
• conditions after strumectomy (thyroid resection),
• conditions after radiation therapy,
• thyreostatic treatment,

fT4 result

Falsely elevated results can be caused by:

• high concentrations of the thyroxine-binding protein TBG,
• drugs (amiodarone, heroin, methadone, shadowing agents).

False low values are caused by drugs (androgens, carbamazepine, diazepam, heparin, betablockers, rarely autoantibodies).

Why should fT4 Thyroxine hormone be tested regularly?

• The fT4 test is usually performed in people who have a suspected hypothyroidism or hyperthyroidism.
• People with hypothyroidism or hyperthyroidism
• People with hypertrophy of the gland, known as goiter, should also check their fT4 regularly.
• Free fT4
• Free thyroxine ft4 testing is also performed in the diagnosis of thyroid cancer, autoimmune diseases or the cause of infertility in women.

Check out the symptoms of hyperthyroidism or hypothyroidism in the next tab.