Extensive Thyroid Hormone Profile
Thyroid hormones are essential in regulating metabolism in adults, and growth and development during pregnancy and infancy. It is essential to conduct a complete thyroid hormone profile to truly assess the availability of the thyroid hormones to the tissues and an individual’s metabolic rate.
This is a non-invasive test that accurately measures thyroid hormone levels including TSH, T3 and T4. This is different from a standard medical blood test that normally only tests TSH. If TSH is “in range” no further testing is conducted, and yet T3 and T4 may not be at optimal levels.
An underactive thyroid (hypothyroidism and sub-clinical hyopthyroidism) is one of the most common hormonal disorders, seen in conjunction with changes in oestrogen and progesterone in peri-menopausal, menopausal and post-menopausal women.
Symptoms of hypothyroid include:
- dry and coarse skin and hair
- hair loss
- weakness and lethargy
- unexplained weight gain or difficulty losing weight
- heavy and irregular periods
- depression and mood disorders
Symptoms of overactive thyroid or hyperthyroidism (thyrotoxicosis) include:
- rapid heart beat
- nervousness and palpitations
- weight loss despite increased appetite
- frequent bowel movements
TSH, T3 and T4
Normally, thyroid-stimulating hormone (TSH) from the pituitary gland stimulates the production of inactive T4 (thyroxine) and active T3 (triiodothyronine) from the thyroid. T4 is converted to T3 in the liver, requiring selenium and zinc.
Reverse T3 (rT3)
T3 is the most active (and some might argue the most important) thyroid hormone, 83% of which is produced from the conversion from T4. Reverse T3 (rT3) is different; it is an inactive form of T3 that is produced in the body particularly during periods of stress.
An increased production of rT3 may also be seen in:
- Fasting and starvation
- Liver disease
- Chronic fatigue syndrome (CFS)
This is an invaluable test as rT3 may be elevated whilst T3 is normal, and indicates poor thyroid function.
Thyroid antibodies may be tested additionally to investigate the presence of autoimmune thyroid conditions Hashimoto’s thyroiditis (autoimmune hypothyroidism) and Graves disease (autoimmune hyperthyroidism).
Approximately 70% of the bodies iodine is in the thyroid gland, thus iodine is intimately connected with thyroid function. The major hormone secreted by the thyroid is inactive T4 (thyroxine), containing four iodine atoms. The removal of one iodine atom converts T4 to active T3 (triiodothyronine). This occurs mainly in the liver and other tissues where T3 acts, such as the brain.
Other actions of iodine include the formation and integrity of normal breast tissue, foetal brain development and function, and anti-microbial effects.
Thus, this is an essential test in helping to determine optimal thyroid function. Furthermore, it is essential to establish appropriate iodine levels prior to pregnancy due to its role in the developing foetus.