If you suffer from fatigue, sluggishness or trouble losing weight, then you might be low on your thyroid hormone. Other symptoms could include intolerance of cold or cold body temperature, brittle/thinning hair, dry skin, constipation or indigestion. You might even be depressed, apathetic, have "brain fog" or low sex drive. Abnormal menstrual cycles or trouble getting pregnant can be also due to low thyroid.
WHAT IS A THYROID?
Thyroid hormone controls your energy, growth and metabolism. The thyroid gland sits in the front part of the neck and makes thyroid hormone from iodine and an amino-acid called tyrosine. Eighty percent of thyroid output is tyrosine with four iodine molecules attached, called T4, but this is not the active thyroid hormone.
Outside the thyroid gland — especially in the muscle, liver, kidney and brain — T4 must have one of its iodine molecules removed to form the active thyroid hormone, called T3, which is the form that gets into the cells to do its work. Thyroid binds to nuclear receptors and commands a whole array of energetic and building processes, from growth and metabolism, to energy production and detoxification.
Control of thyroid production is overseen by the pituitary gland, a small pea-sized structure that resides in the lower central portion of the brain. The nearby brain area called the hypothalamus determines if there is enough thyroid hormone in the body, and if not it sends a signal to the pituitary to increase thyroid production. The pituitary then releases thyroid stimulating hormone (TSH), which urges the thyroid to ramp up production of thyroid hormones.
Low thyroid is called hypothyroidism, and "primary" hypothyroidism is when the thyroid gland is impaired and quits making thyroid hormone. "Secondary" hypothyroidism is when the thyroid gland is fine, but the pituitary is damaged and does not send the proper TSH signal, or the thyroid gland does not get the signal.
The most common textbook form of primary hypothyroidism is called Hashimoto's, in which the body makes antibodies that attack the thyroid and turn off thyroid production. We find this most commonly in women, age 30-50, often after pregnancies or around menopause.
Some people have low thyroid due to iodine deficiency. There is debate as to whether the iodine in our table salt supply is really enough for optimal health. We recommend testing for iodine levels and supplementing only if indicated.
Secondary hypothyroidism can be due to anything that damages the pituitary or interferes with the ability of TSH to work properly. Inflammation and the stress hormone cortisol both interfere with pituitary output, causing a low-grade impairment of TSH production from the pituitary. Head injuries are a common cause of subtle pituitary damage.
I have hundreds of patients with low thyroid that are "under-converters" — who do not convert their T4 to T3, and as a result are low on thyroid. The lack of conversion can be due to aging, stress, prolonged illness, toxic metal or chemical exposures, other hormone imbalances, nutrient deficiencies and medications, amongst others.
BEWARE OF 'NORMAL' THYROID TESTS
The standard blood test for diagnosing and monitoring thyroid conditions is thyroid stimulating hormone (TSH) from the pituitary gland. TSH goes up to promote thyroid production, so if TSH is high, it suggests low thyroid, and visa-versa. There are numerous reasons, well documented in the endocrinology literature, why this test alone can't be trusted and is not at all sufficient to monitor thyroid status.
I recommend patients also get a free T4 and free T3 blood test, as well as two tests for antibodies to the thyroid, TPO and thyroglobulin antibody. Sometimes even the better blood tests are not accurate in determining thyroid status. The blood level of thyroid hormone may not reflect the level that actually gets into the cells or the cells may be resistant to thyroid hormone.
Not every low thyroid condition requires thyroid hormone. Often, Hashimoto's is curable. Controlling high stress and cortisol can improve thyroid function. Eliminating sugar and high glycemic foods from the diet will improve all hormone functions. Supplying nutrients for thyroid production, eliminating exposures to thyroid-toxic chemicals or chelating heavy metals out of the system can help improve thyroid function.
Most physicians use T4-only thyroid hormone for replacement, such as Levothyroid or brand name Synthroid. This is just fine as long as people convert the T4 to the active T3. Some patients do markedly better on forms of thyroid hormone that contain both T4 and T3, such as brand name Armour thyroid. And still other patients will only feel normal by taking a T3-only type of thyroid replacement.
If you are suspicious that you have a thyroid problem, ask your physician to check the blood tests suggested above. This will give you a starting point for treatment. If the blood levels are within the normal range, but you still have symptoms of low thyroid, you may need to consider some of the conditions mentioned above in order to have your thyroid "normal" for you.
If you have symptoms of low thyroid and they don't seem to relate to anything else, then you very likely are low on thyroid hormone. The routine blood tests might be "normal," even if your thyroid function is not.
GJ Free Press health columnist Scott Rollins, M.D., is board certified with the American Board of Family Practice and the American Board of Anti-Aging and Regenerative Medicine. He specializes in bioidentical hormone replacement, thyroid and adrenal disorders, fibromyalgia and other complex medical conditions. He is founder and medical director of the Integrative Medicine Center of Western Colorado (www.imcwc.com) and Bellezza Laser Aesthetics (www.bellezzalaser.com). Call 970-245-6911 for appointments or more information