Thyroid Test Results – What You Need to Know

Nothing is more confusing than thyroid test results especially when it’s not uncommon to only see TSH and T4. What’s worse is that you may have thyroid stimulating hormone (TSH) numbers within range but still feel terrible!

I remember going to my endocrinologist and asking why is it that he just tests for TSH and occasionally T4. His response was that the TSH is how he prescribes thyroid hormone replacement. I really felt there was more to it though so I began to explore functional medicine. 

The problem with just testing for TSH is that it doesn’t show how your body uses the T4 hormone. You may be feeling poor because your body isn’t converting it to free T3. So what do you ask for on your next visit?

What Thyroid Tests to Request

I want you to know all the thyroid tests to requests and what they mean. Be sure to bookmark this for future reference!


Thyroid stimulating hormone (TSH) is actually a pituitary hormone.  When TSH is secreted it’s asking the thyroid gland to produce thyroid hormones T4 and T3. High TSH can indicate a disorder of the thyroid gland while low TSH can indicate over-production of T4 and/or T3 which then causes the pituitary to reduce TSH production. Low TSH can also be caused by problems in the pituitary gland itself. 

The ideal range for TSH is .5-2.0/2.5 uU/mL.

Free T4

T4 (thyroxine) is an inactive hormone produced by the thyroid gland that’s converted to the active form, T3 within cells. It’s like a storage hormone. By itself, it isn’t usable. It must be converted to T3 within cells to be usable. Free T4 represents 0.4% of the total T4 levels. High TSH combined with low free T4 indicates hypothyroidism while low TSH and high free T4 indicates hyperthyroidism. 

thyroid test results

The ideal range for Free T4 is 1-2 ng/dL.

Free T3 

Free T3 (Triiodothyronine) is the active form of thyroid hormone that regulates the metabolic activity of cells. Free T3 is bound to protein and considered the active form. Elevated T3 levels are seen in hyperthyroidism but levels can be normal in hypothyroid patients because it doesn’t represent the conversion of T4 to T3. 

The ideal range for Free T3 is 3-4 ng/dL.


TPOab (Thyroid Peroxidase Antibodies) is an enzyme used by the thyroid gland to make thyroid hormones by liberating iodine for attachment to tyrosine on thyroglobulin. This is detected in 95% of people with Hashimotos and around 70% of those with Graves’ disease. In patients with autoimmune thyroiditis (Hashimotos), the body produces antibodies that attack the thyroid gland. When TPOab levels are high, this can indicate an autoimmune disorder. Thyroglobulin is an indicator of the person’s average iodine exposure over the period of weeks. The greater the iodine, the lower the thyroglobulin. 

Ideal range of TPOab <50/75 most labs will be below 20 and you want this number to be as close to 0 as possible.

Symptoms of Thyroid Problems

When your thyroid isn’t functioning properly, symptoms can include:

  • Weight gain or inability to lose weight even with exercise and diet
  •  Feeling cold all the time when others don’t
  •  Low energy and stamina (unrelieved by sleep)
  •  Irregular bowel habits – constipation/loose stools  Dry, thinning, or itchy skin
  •  Hair loss
  •  Insomnia
  •  Water retention
  •  Menstrual irregularities
  •  Low sex drive
  •  Infertility
  •  Memory lapses or slow/fuzzy thinking
  •  Dry/brittle hair and nails
  •  Depression
  •  Osteoporosis
  •  Weight loss
  •  Muscle and joint aches and pains
  •  High blood pressure
  •  Increased cholesterol levels
  •  Heat or cold intolerance

What Else Can Affect Thyroid Function?

Like anything in the body, it’s not a closed system. Thyroid function can be affected by the function of other hormone systems such as estrogen and cortisol, by nutritional deficiencies particularly iodine and selenium and by environmental toxin exposure. Bromine (a flame retardant), arsenic (common in rice), selenium (this is rarer as we tend to be deficient), mercury (from silver dental amalgams, fish and water contamination) and cadmium. 

Conventional medicine practitioners can test for the thyroid (and pituitary markers) and estrogen levels but won’t necessarily be able to test for elevations in contaminants, nutrient deficiencies and toxicities. Functional medicine labs, however, can do this well.

I work with clients to find underlying root causes of their imbalances and symptoms using functional medicine lab testing. Then, I develop personalized protocols based on my client’s symptoms and lab test results. If you’d like to explore how to work with me, visit my one-on-one coaching page and book a free chat to see how I can support you.

Disclaimer: This article is provided for informational purposes only. It is not intended to diagnose, treat or cure disease. If you suspect you have a thyroid dis-ease, contact your primary care provider.


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