Thyroid Function Testing
Dr. Nusbaum has been interested in how the thyroid affects aging for many years. Did you know that all hormones interact with each other? Changes in one hormone invariably affect the activity and behavior of other hormones. For instance, testosterone is converted in fatty tissue to estrogen by an enzyme called aromatase, and the administration of testosterone may increase estrogen levels as well when needed. In addition, the symptoms of different hormone deficiencies overlap. Fatigue, for instance, may be a manifestation of deficiency of estrogen, testosterone, thyroid hormone, or cortisol, or of several of them at the same time.
Thyroid hormone status should be assessed in all patients undergoing consideration for hormone replacement therapy. Thyroid hormone activity impacts both the production and the activity of sex hormones. Hypothyroidism may suppress menstruation, and cause many of the symptoms of menopause: fatigue, weight gain, depression, memory loss, hair loss, dry skin. A woman may appear to be entering menopause when in fact she has a thyroid disorder, and correction of her thyroid would restore her menses and may eliminate the other symptoms.
Hypothyroidism is very common in women, affecting over 10%. It is generally an autoimmune disorder, meaning an attack by the body’s immune system against itself, and anti-thyroid antibodies can be measured. It occurs less frequently in men. Thyroid insufficiency may raise blood pressure and cholesterol, increasing the risk of cardiac disease.
Treatment generally involves administration of thyroid hormone in doses to normalize the TSH (Thyroid Stimulating Hormone) level. Symptoms start to improve in less than a week. The most economical and popular replacement treatment is oral Synthroid or its generic equivalent. Animal-derived formulations containing both T3 and T4, called Armour thyroid or Naturthroid are also available. Most commercial preparations contain only T4, which some individuals do not easily convert to T3, which is the more active form of thyroid hormone. Thyroid-related depression should be addressed with T3 augmentation if indicated.