Thyroxine, otherwise known as T4, is a hormone produced and secreted by the thyroid gland. At the tissue level, T4 is converted into the more active form of the hormone called T3. For this reason, T4 is considered a measurement of total production of thyroid hormone.
Hypothyroidism is a condition where T4 blood levels are low. This causes cellular dysfunction and metabolic breakdown. Symptoms may include weight gain, constipation, dry skin, and hair loss. Low T4 levels may even lead to the development of chronic diseases such as heart disease and diabetes.
Hyperthyroidism is the term for elevated T4 blood levels. Symptoms can include anxiety, insomnia, heart palpitations, and bowel discomfort.
Fasting is not required for this test. Take all medications as prescribed.
For a more extensive evaluation of thyroid function, Life Extension® offers a Comprehensive Thyroid Panel.
The laboratory services are for informational purposes only. It is not the intention of National Diagnostics, Inc and Life Extension to provide specific medical advice but rather to provide users with information to better understand their health. Specific medical advice including diagnosis and treatment will not be provided. Always seek the advice of a trained health professional for medical advice, diagnosis or treatment.
Both the physician and the testing laboratory are independent contractors with whom National Diagnostics, Inc makes arrangements for your blood tests. Neither National Diagnostics, Inc or Life Extension will be liable for any acts or omissions of the physician, the testing laboratory, or their agents or employees.
Product reviews are provided for informational purposes only and reflect solely the views and opinions expressed by the contributors and not those of Life Extension. We do not verify or endorse any claims made in these reviews. Please read the full product reviews disclaimer.