- Thyroxine (t4) Test (total) is designed to test for Total Thyroxine (T4) hormone and accurately assesses T4 levels in the blood
- Analyse Stability: The dried blood spot samples are stable for more than 1 month at room temperature.
- Contains Blood Spot collection kit
- Test sample can be collected at the comfort of your home
- Free delivery in the UK (International delivery from £3.99)
- Customers are responsible for shipping their sample to laboratory.
- Test kit includes laboratory fee. No additional laboratory cost and tax.
- Test Result: You will receive your test result via email within 3-5 working days after Laboratory receives your sample. On your test result you will see your hormone levels in graphics and numbers. You will also see Laboratory's comments by Hormone Specialist Phd Dr. on your test result which suggests a healthy diet, what kind of exercise you should do and some reading materials how to maintain your hormone level balanced. After receiving your test result we strongly recommend you to show your test result to your GP and see if you need any treatment or further action needs to be taken.
- Test must be used within 12 months after purchase date.
- Test Requisition Form includes Symptom Checklist
- Requisition Form to complete including your personal and medical history
- Contains collection instructions
- Instructions on How to Use blood spot Collection Kit
- Shipping Instruction
- Return Envelope
Thyroxine (T4) is the primary thyroid hormone circulating in the blood. Total T4 includes both free T4 and protein-bound T4, and therefore represents the thyroid gland’s capacity to synthesize, process, and release T4 into the bloodstream. In contrast, free T4 and free T3 are representative of the bioavailability of active thyroid hormones to peripheral tissues. A low level of total T4 with elevated levels of thyroid-stimulating hormone (TSH) and thyroglobulin suggests hypothyroidism caused by either low iodine intake, or inhibition of iodine uptake or the iodination of thyroglobulin by goitrogens.
Excessive amounts of iodine can result in either hypo– or hyperthyroidism, depending on preexisting conditions. For example, elderly people who have lived for a long period in a low iodine environment develop autonomous thyroid nodules as a compensatory mechanism to boost thyroid hormone production. When iodine exposure is suddenly increased, these nodules hyper-respond and the result is hyperthyroidism with high T4 production. On the other hand, hypothyroidism as a result of excess iodine can occur when iodine forms iodolipids within the thyroid follicle that inhibit the iodination of thyroglobulin, depressing T4 and T3 synthesis (the Wolff-Chaikoff effect). This can usually be reversed by lowering iodine intake to less excessive amounts, so that thyroid hormone synthesis returns to normal. However, individuals with pre-existing subclinical hypothyroidism or Hashimoto’s disease may progress to a permanent clinical hypothyroid state and require thyroid hormone medication. The reference range for total T4 is 5—10.8 µg/dL.
How to Use