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Free Thyroxine (fT4) and another hormone called triiodothyronine (T3) are produced by the thyroid gland. They help control the rate at which the body uses energy and are regulated by a feedback system. TSH stimulates the production and release of T4 (primarily) and T3 from the thyroid gland.
Most of the T4 and T3 circulates in the blood bound to protein, while a small percentage is free, meaning not bound. Blood tests can measure total T4, free T4, total T3, or free T3. The total T4 test has been used for many years, but it can be affected by the amount of protein available in the blood to bind to the hormone. Free T4 is not affected by protein levels and is the active form of thyroxine. The free T4 test is thought by many to be a more accurate reflection of thyroid hormone function and, in most cases, its use has replaced that of the total T4 test.
Your blood spot samples will test: Free Thyroxine (fT4) levels.
You may want to consider this test if you want to:
- Detect too much or too little thyroid hormone
- Distinguish between different thyroid disorders
- Help diagnose pituitary disorders
- Aid in the diagnosis of female infertility
- Monitor the effectiveness of thyroid disorder treatment
- Screen for thyroid disorders
Everything you need to collect your sample and return it to the lab is included in the test kit you will receive.
You can review these illustrated Collection Instructions now or wait to receive them in your package.
Your test results will be returned to us within 5 to 7 business days from the date the lab receives your sample. Once we know that your results are available, we will send you an email so that you can login and review them.
NOTE: Per state laws, if you live in California, you will need to email us a prescription from a medical practitioner (could be a physician, physician's assistant, naturopath etc.) in order for us to process your order and send you your test. New York residents may not receive tests per state laws. Having your tests shipped to you outside of California or New York may be the best way to go. (The Air Quality tests and Pet tests do NOT need a prescription and can be sent anywhere needed.)
Because the test kits include postage-paid return shipping, there is an extra shipping charge of $10.00 that will be added to your test order.
This Free Thyroxine (fT4) test is used to help evaluate thyroid function and diagnose thyroid diseases, including hyperthyroidism and hypothyroidism, usually after discovering that the thyroid stimulating hormone (TSH) level is abnormal.
Please note that because return postage is included with this test kit, there is an extra shipping charge of $10 for kits shipped in the USA. The extra shipping charges for kits shipped outside the USA will vary according to cost/location. (This extra charge is NOT added to the Canine Health Check Test Kit or Any of the Air Quality Test Kits.
Everything you need to collect your sample and return it to the lab is included. You should receive your results approximately 5 to 7 business days after the lab has received your sample. There are no additional lab or postage fees required after test purchase.
This is a safe, easy to use home blood spot test for men and women of any age.