Hypothyroidism: An Undertreated Illness
Hypothyroidism is usually described as a condition caused by an under-function of the thyroid gland. However I prefer to describe it as a condition whereby the body is deprived of the influence of active thyroid hormone. I prefer this definition because there are several conditions where in the thyroid gland may be functional, but either the quality of the active hormone is inadequate, or toxic substances in the body curtail transport of the hormone across cell membranes depriving the cell of adequate amounts of hormone. Of course the thyroid gland itself may be dysfunctional, unable to produce adequate amounts of thyroid hormone, or as we age, active thyroid hormone is produced less in the body.
Symptoms of low thyroid function are fatigue, sleep disturbance, weakness, depression, weight gain, dry skin, falling hair, cloudy thinking or abnormal hormone function. Many patients have these classic signs but are never diagnosed with this problem because their thyroid tests are normal.
Proper Thyroid Function
As with all glands in the body, the pituitary gland exerts primary control. Thyroid Stimulating Hormone (TSH) is produced in the pituitary and stimulates the thyroid gland to produce thyroxin T4, liothyronine T3, and triiodotyrosine. T4 is not metabolically active but must be converted to T3 to be effective. T3 is the most active hormone which stimulates normal metabolic function within each cell. A normal amount of T3 and T4 in the blood feeds back to the pituitary to curtail production of TSH.
Therefore if a poorly functional thyroid glad does not produce enough T3 or T4, the pituitary produces more TSH in an attempt to stimulate the thyroid gland to produce more hormone. So a high TSH level in the blood would indicate an abnormally low T3 and T4 production, which in turn means low metabolic function. a very low TSH level on the other hand means a greater production of T3 and T4, since the pituitary does not have to prime the thyroid gland quite as much.
Most physicians rely solely on the TSH level to determine whether the thyroid gland is producing enough T3 and T4. This test can be exceedingly misleading if someone is taking thyroid hormone as therapy for low thyroid function, or if the quality of the T3 produced by the thyroid gland is not normal. A person with a normal T3, T4, and TSH can be hypothyroid if the thyroid gland produces reverse T3, instead of normal T3. Reverse T3 is not metabolically as active as normal T3, and therefore despite normal blood tests, a person can be suffering from a lack of normal thyroid hormone in cells. This condition is known as Wilson's Syndrome. It is also a medical fact that as one ages, the deiodinase enzyme which conterts T4 to T3 becomes less efficient in its activity. There despite a normal TSH level, actual influence of thyroid hormone on the system can deteriorate.
Toxins circulating in the body can saturate receptor sites on cell membranes and can also damage them thereby making them unavailable for hormones and other essential cellular nutrients. Once receptor sites are damaged or saturated, thyroid hormone circulating in the bloodstream becomes unavailable to the cell in required amounts producing the symptoms of hypothyoidism. In this case, blood tests may be normal.
Testing Thyroid Effectiveness
One way of testing the effect thyroid hormone is the basal temperature test. The temperature is taken using a mercury thermometer, shaken down at bedtime, and placed under the armpit immediately upon awakening in the morning, before getting out of bed or before any movement. The thermometer is kept under the armpit for 10 minutes and the temperature recorded. Those with temperatures below 97.8 were found to have low metabolic function due to an abnormality of thyroid absorption in the cell or inadequate production of T3 or T4.
In all these cases, the use of the natural thyroid hormone (Armour) is the most useful since it contains controlled amounts of T3 and T4. Synthetic T4 (Synthroid) will not work if the enzyme required to convert T4 to T3 is not normal. Often patients are placed on Synthroid or a similar drug for low thyroid and feel no different even though the TSH levels become normal. The reason is obvious. Their T4 is not converting adequately to the active T3 hormone or not enough T3 is getting into cells for whatever reason. The blood test looks great - the patient feels lousy.
Although hyperthyroidism can be elusive, some detective work can often clinch the diagnosis and appropriate treatment given.