Thyroid hormone- Free triiodothyronine (FT3)


  • Results within 24 hours

  • Blood draw included

Hyperthyroidism is when the thyroid is over active and can lead to symptoms such as weight loss and thinning of hair. This blood test will provide a measure of FT3 which can be used to diagnose this condition. A high free T3 result may indicate an overactive thyroid gland (hyperthyroidism) whereas a low free T3 results may indicate an underactive thyroid gland (hypothyroidism).

What are the symptoms of hyperthyroidism?

  • Anxiety
  • Mood swings
  • Thirst
  • Muscle weakness
  • Sensitivity to heat
  • Difficulty sleeping
  • Hyperactivity
  • Diarrhoea

Is any preparation for the test needed?

A variety of medications can interfere with the test, particularly contraceptives and large doses of aspirin, if these are an issue advice will be given prior to the test, but free T3 is impacted less by these medications. If you are sick it is best to wait before having a FT3 test, as your body decreases the production of T3.

How is hyperthyroidism treated?

Treatment for an overactive thyroid often includes taking thionamides, this medicine prevents your thyroid from producing excess hormones, the types most often used in treatment are called carbimazole and propylthiouracil.