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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.
High levels of T4 are associated with symptoms such as anxiety, insomnia, diarrhea, and muscle aches and pains. These symptoms collectively are known as hyperthyroidism.
Low levels of T4, known as hypothyroidism, are associated with symptoms such as depression, weight gain, dry skin, hair loss, constipation and cold intolerance.
Fasting is not required. Take all medications as prescribed. Do not take supplements the day of the test. This test is also included in the Life Extension 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.