A small, butterfly-shaped gland situated in the front of the neck, the thyroid is a little organ with a very big job: It primarily produces hormones that regulate body metabolism — energy produced through the food you eat. These hormones act as messengers that tell your tissues when to burn energy and how to develop.
Two hormones that emanate from the brain — thyrotropin-releasing hormone (TRH), made in the hypothalamus, and thyroid-stimulating hormone (TSH), produced by the pituitary gland — control the thyroid gland's release of its two main hormones: thyroxine (T4) and triiodothryonine (T3).
T4, the most abundant and long-lasting thyroid hormone, is used as a precursor to make T3, which is the more potent thyroid hormone. It has a shorter half-life and the majority is produced from T4 within peripheral tissues. Reverse triiodothyronine (rT3) is an inactive isomer (a compound sharing a similar molecular formula but differing in structure) of T3, which blocks the effect of T3 at the receptor site.
As you age, you are more likely to experience thyroid dysfunction. It is estimated that 3% to 8% of the general population suffers from subclinical hypothyroidism or mild thyroid failure1— a condition where the thyroid does not produce adequate amounts of the hormones thyroxine (T4) and triiodothyronine (T3) to suit individual needs. The majority of those afflicted with subclinical hypothyroidism tend to have high-normal serum TSH values and low-normal free T4 and free T3 levels.
Since thyroid levels may not appear obviously out of range, this type of thyroid dysfunction can be quite difficult to diagnose. For practitioners who rely solely on a TSH measurement, often considered the gold-standard for assessing thyroid status, making an accurate diagnosis can be even more challenging. Unfortunately, a patient who has been experiencing symptoms of subclinical hypothyroidism and has undergone repeated blood testing may never receive proper treatment because many physicians will view the patient's blood levels as "normal."
Normal is NOT Optimal
Laboratory reference ranges are a set of values that have been assigned to specific biochemical measurements within a given medium (blood, saliva, tissue) in the body. These intervals were established from population studies conducted by laboratories many decades ago and have not been upgraded since.2 In fact, it is very likely that the selection criteria did not exclude those with subclinical disease.
The problem with relying solely on the TSH test for diagnosis of subclinical hypothyroidism is that by the time it becomes relevant, the disease already could be ravaging the tissues, leading to substantial destruction and dysfunction. A combination of blood testing and symptom recognition could have identified the condition early on, thus preventing significant damage. Diagnosing thyroid dysfunction should not be limited to examining just TSH levels, but should also include free T4, free T3, and thyroid antibodies — TPO and antithyroglobulin (TgAb).
Approximately 80% of those suffering from subclinical hypothyroidism will test positive for thyroid antibodies3 — proteins that stimulate an inflammatory immune response and cell destruction. Recent studies have shown a greater presence of thyroid antibodies in those with a TSH level between 3.0 and 5.0, and a trending shift toward developing overt clinical hypothyroid disease.4 People with the lowest incidence of thyroid disease/autoimmune thyroiditis had an average, optimal TSH of 1.18µIU/mL.5 There is a major discrepancy between an "optimal" TSH level of 1.0 and a "normal" TSH that falls somewhere between 0.45 and 4.0 µIU/mL. You're not crazy: You feel sick because your thyroid levels are not optimal for what your body needs!
What can I do?
If you suspect you are suffering from subclinical hypothyroidism, monitoring your health is essential. First, keep track of your symptoms: Be especially aware of how you have been feeling and take your basal body temperature each morning. An initial indicator of an underactive thyroid is a lower body temperature.6 Document this information in a journal if you tend to forget. Schedule an appointment to share this information with your practitioner, or consult ForeverHealth.com to find a local practitioner who specializes in treating thyroid conditions.
Common symptoms of subclinical hypothyroidism include:
- Feeling Cold
- Weight Gain
- Dry Skin/Coarse Hair
- Muscle and Joint Discomfort
Second, take a blood test to measure your levels of thyroid hormones and antibodies — a full-spectrum panel that includes TSH, free T4, free T3, reverse T3, and thyroid antibodies. As mentioned previously, the goal is not to be "normal" but to be "optimal." A TSH level between 1.0 and 2.0 µIU/L is IDEAL and has a lower association with disease risk. Corresponding optimal free T4 and free T3 levels should be situated within the upper-third of the reference interval. Ideal reverse T3 values should be <20 ng/dL or <200 pg/mL. A negative to low-level presence of antibodies is also ideal. Forever Health offers a comprehensive Thyroid Panel that includes all these measurements; check out our blood test section for more information.
Managing Subclinical Hypothyroidism
After a thorough evaluation of your chief complaints and objective data, including labs, your practitioner may suggest various treatment options. In cases where medication or prescription-strength resolutions are warranted, he or she may opt for a bioidentical glandular T3/T4 combination called Nature-Throid or Armour Thyroid. Using one of these compounded formulas is the most effective way to optimize both T4 and T3. Keep in mind, however, there are unique situations where you may respond better to the traditional thyroid medications: Levothyroxine (Synthroid/T4) or Liothyronine (Cytomel/T3). With either option, be sure to keep track of any changes in symptoms and continue monitoring your thyroid levels so dosing can be adjusted if needed.
- Endocrinol Metab (Seoul). Mar 2014;29(1):20–29.
- Am J Clin Pathol. 2010;133(2):179.
- Mayo Clin Proc. 2009 Jan; 84(1):65–71.
- Subclinical Hypothyroidism. http://www.patient.co.uk/doctor/subclinical-hypothyroidism. Published 2015. Accessed May 19, 2015.
- J Clin Endocrinol Metab. 2005 Sep;90(9):5483-8.
- P R Health Sci J. 2006 Mar;25(1):23-9.