FT4 can tell whether the thyroid is performing properly. It aids in the diagnosis of hypothyroidism or hyperthyroidism. The test may also be used to help evaluate a patient with an enlarged thyroid gland, called a goitre. It may also aid in the diagnosis of female infertility problems.
Many medicines including oestrogen, certain types of contraceptive birth control pills, those drugs used to help control epilepsy and large doses of aspirin could interfere with total T4 test results, so tell your doctor about any drugs you are taking. In general, free T4 levels are minimally affected by these medications, another reason why FT4 is routinely used to assess thyroid function.
This article was last reviewed on 16 January 2017. | This article was last modified on 16 January 2017.
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