Hypothyroidism confirmed by laboratory analysis is sometimes not obvious with traditional testing. Subclinical hypothyroidism is relatively common yet often missed with basic thyroid screening. TSH (thyroid stimulating hormone) is usually the lab test ordered to rule out a thyroid condition, whether it is hypothyroidism, hyperthyroidism, Hashimoto’s or Graves disease. 

For a complete analysis to determine if there is an auto-immune thyroid disease, subclinical hypothyroidism or cellular hypothyroidism, a minimum of 6 blood tests should be evaluated. TSH levels have a broad range that is conventionally considered normal. However, for optimal thyroid health, TSH should be within a very narrow scope and should always be compared to the other thyroid hormones. Free T4 is the most abundant thyroid hormone and it is made in response to TSH levels in the thyroid gland. This hormone is mostly inactive and becomes activated when it is converted into T3 in the kidneys, liver and body cells. T3 is very active, 20% is made in the thyroid itself, it controls the rate of metabolism which leads to balance with weight, hair growth, mood, body temperature, menstrual cycles, digestion and pretty much every aspect of the human body.

Reverse T3 (rT3) is an important thyroid hormone but when elevated can point to conditions not related to thyroid. This blood marker is not conventionally tested but is very important to evaluate when diagnosing cellular hypothyroidism. T4 converts into both T3 and rT3, however rT3 is inactive and cannot contribute to an increased metabolic rate. When over producing rT3, not enough T3 can work to improve metabolism and cells become hypothyroid. Symptoms are any of the classic hypothyroid symptoms – hair loss, tiredness, weight gain, acne, depression, menstrual cycle irregularities and so on. However lab analysis can show healthy and normal TSH, T4, and T3 levels to give the impression that thyroid levels are optimum. It is not until rT3 and T3 are compared and a ratio is calculated that cellular hypothyroidism is apparent. 

The last of the 6 hormones in a comprehensive thyroid analysis are the antibodies. Anti-thyroperoxidase (anti-TPO) and anti-thyroglobulin antibodies are both made naturally in very small amounts to help the body recycle thyroid proteins when their lifespans have finished. However, in the auto-immune disease Hashimoto’s thyroiditis, either or both antibodies can be elevated above baseline because the body’s immune system has started an immune response against the thyroid using these antibodies. In some instances TSH, T4, T3 and rT3 are all healthy yet the auto-immune markers are high. Thyroid medication might not be required but there are many ways to lower the inflammation and prevent the need for hormone replacement in future. There are a few other antibodies that can be ordered to rule out hyperthyroidism caused by Grave’s disease too such as thyroid receptor antibodies.

Additional testing can be helpful to determine the surrounding aspects of thyroid health such as ability to convert thyroid hormones, transportation of hormones, utilization of hormones and even factors that contribute to auto-immune thyroid. Sex hormone binding globulin (SHBG) will bind to estrogen, testosterone and thyroid thus levels and can be used to look deeper into these hormone abilities. SHBG helps to transport hormones through the blood to the tissue and is made in the liver. Testosterone and insulin can also act to lower SHBG while estrogen and thyroid stimulate liver production of SHBG. Evaluating the levels of SHBG to the other hormone levels gives insight and further ways to evaluate hidden subclinical hypothyroidism.

Conversion of T4 into T3 can be both upregulated (increased) or downregulated (decreased) based on vitamins, minerals and other hormones. Selenium, magnesium, zinc, iron, Vitamin B12, Vitamin D and iodine are all connected to thyroid hormone levels. Sometimes correcting hypothyroidism is possible with replacing the deficient nutrients. These nutrients can be evaluated along with the 6 thyroid markers for a complete analysis.

A full baseline blood analysis of thyroid health can be ordered very simply with one trip to the lab. This includes:

  • Enhanced thyroid assessment: TSH, free T4, free T3, reverse T3, Anti-TPO, antithyroglobulin
  • Selenium, zinc, red blood cell magnesium
  • Ferritin (stored form of iron)
  • Vitamin D and Vitamin B12
  • Sex hormone binding globulin

Additional considerations to get the full picture of hormone health and the barriers to hormone production include evaluation of cortisol levels, sex hormones, heavy metals, urine iodine, insulin production and digestive analysis. Because the human body works together as a group of interacting systems, the connections between different hormones and ability to absorb nutrients well from a digestive health perspective are also part of the picture.

Hormones can be evaluated by blood, urine or saliva with each fluid offering differing ways to view levels, production and elimination of hormones. For example, the stress hormone cortisol can be tested by saliva or urine. A blood cortisol test is affected by day to day ups and downs so testing by blood can give a wide range of variability whereas saliva and urine are pooled values over time which gives an average. Elevated cortisol will lead to higher rT3 production and thus a hypothyroid symptom picture is observed. However, treatment efforts should primarily focus on lowering cortisol to improve thyroid hormone conversion to free T3.

Additional testing surrounding thyroid health can include the following specialty tests:

  • 4 point saliva cortisol
  • DUTCH complete testing – dried urine analysis of 4 point cortisol, estrogen, progesterone, testosterone, DHEA, melatonin and the breakdown products of these hormones
  • Heavy metal toxicity testing (lead, aluminum, mercury and other toxic metals, evaluated by urine provocation)
  • Genetic testing
  • Urine iodine
  • Digestive flora balance – microbiology stool analysis and SIBO breath testing

What Does the Thyroid Gland Do

The thyroid, which sits underneath the voice box at the base of the neck, is a butterfly-shaped gland of the endocrine system. Humans cannot survive without the hormones produced by the thyroid gland yet too much can also cause a serious health condition.

Thyroid hormones T4 and T3 are both produced in the thyroid gland, but T4 is made at a much higher rate. T3 is mostly made by the removal of one of the four iodine molecules included in T4 and this takes place in the thyroid gland but more so in the cells of the body, liver and kidney. T3 sets the pace or the metabolic rate that the whole body runs at. This means in a simplified explanation how slowly or quickly the cells use energy, convert substrates, detoxify and basically function.

Relating at a larger scale, the metabolic rate when too slow will lead to weight gain, fatigue, depression, heavy, irregular or painful periods, hair loss, acne, cold body temperature or difficulties in general with temperature regulation. Dry skin, brittle nails, dry eyes, low libido, brain fog, difficulties concentrating, constipation, muscle and joint aches are also associated with hypothyroidism.

When upregulation of hormone production or hyperthyroidism occurs, the opposite symptoms can be felt. Insomnia, anxiety, heart palpitations, sweating with heat, increased urination or frequency of bowel movements and diarrhea are some symptoms. Interestingly fatigue can be associated with hyperthyroidism and hypothyroidism. The most common reason for hyperthyroidism is Grave’s disease.

Common Thyroid Conditions

By far, hypothyroidism is the most common condition that affects the thyroid. Lack of thyroid hormone production leads to a slower metabolic rate and conventionally an elevated TSH above the lab reference range constitutes the diagnosis. Many people experience hypothyroid symptoms but have a TSH within the reference range. This is when a complete thyroid assessment of all 6 markers and additional nutrient and hormone testing can verify subclinical hypothyroidism. This just means that the body has a lower metabolic rate due to lack of thyroid hormone, but the TSH doesn’t correlate.

Cellular hypothyroidism is slightly different. The easiest way to think about it would be that the levels of the thyroid hormones are normal and often strong, but they are not getting transported into the cells and/or used at a normal rate. This can only be detected by looking at reverse T3 along with TSH, T4 and T3. By far this would be the most difficult to diagnose if only the TSH is tested and even if T4 and T3 are tested too, the key is rT3.

Hyperthyroidism occurs when there is an overproduction of T4 and/or T3. This is common to Grave’s disease and usually comes on suddenly over a short period of time. It can be triggered by stressful events such as pregnancies, extreme grief or stress or other big health events.

Hashimoto’s thyroiditis is the most common reason why hypothyroidism has occurred. When the thyroid is being attacked by the immune system, inflammation and destruction of thyroid tissue occurs. This often results in less thyroid production and a hypothyroid picture, but sometimes flares can induce a hyperthyroid state. This condition can be determined by testing for thyroid antibodies by blood.

Why is Thyroid Testing Important

Thyroid hormones regulate every body system to some extent. The digestion rate depends on thyroid hormones to move at a healthy rate and not lead to diarrhea if too quick or constipation if too slow. Sex hormones production – testosterone, estrogen and progesterone are all linked to thyroid hormone and can help libido, sexual function and menstrual cycles.

Symptoms may seem to be clearly related to one body system yet if that system’s regulation is not optimal, roots can be tied back to thyroid hormone production. By evaluating the important 6 thyroid markers, a thyroid condition can be uncovered and properly treated.

What are Thyroid Tests Like

Thyroid tests are best evaluated by a blood test. There are urine hormone tests but those prove to be less accurate and should not be used to confer a thyroid hormone condition. When arriving at the laboratory, a simple blood test will be administered and should take less than 5 minutes.

A thyroid report comes relatively quickly once the blood sample has been taken. Only a few days later, the TSH, T4, T4 and both antibodies will be reported. Reverse T3 takes up to 2 weeks to get results since it is a specialty test that requires a specific laboratory in California to measure.

Frequently Asked Questions

A blood test which is fasting and in the morning will yield the most accurate results. If on thyroid replacement hormones, do not take your medication the morning of the test. It can be consumed right after the blood draw so as not to miss a dose, but T3 levels may look elevated from baseline if medication is taken prior. There are some experts that suggest women should not test between Day 10-20 of their menstrual cycles due to the effects of estrogen at that time.

The genetic link between family members with hypothyroidism is Hashimoto’s thyroiditis. Testing both thyroid antibodies may reveal an early-staged thyroid condition where prevention of development is still possible.

Yes. Conventional testing is only TSH unless that is elevated or too low. Many people suffer from subclinical hypothyroidism which can be uncovered with evaluation of TSH, T4, T3 and rT3.

Yes. Knowing the amount of inflammation that is present helps to dictate the best treatment options. The levels can also be used as a benchiline for treatment and re-test in 6-12 months to determine the rate of change.