There are a number of different blood tests for thyroid conditions, maybe you have taken a thyroid test or you’re thinking about checking your thyroid in the future. It’s great that you are taking control of your health but understanding what your results mean is just as important.

Let’s talk about what your thyroid results actually mean.




What your thyroid stimulating hormone (TSH) results mean


Thyroid stimulating hormone, which is also known as TSH is a pituitary hormone that is produced and released by the pituitary gland in response to fluctuating levels of thyroxine and triiodothyronine in the blood.

Thyroid stimulating hormone plays a significant role in regulating metabolism, the body’s basal temperature, energy levels, mood and muscle strength.

If thyroid hormone levels are low, the pituitary gland is stimulated to produce more thyroid stimulating hormone. If thyroid hormones are normal or high, the pituitary gland will cease in producing thyroid hormones.

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What does high thyroid stimulating hormone (TSH) mean?
If your results show that you have a high concentration of circulating thyroid stimulating hormone, it may indicate that the thyroid gland is not producing enough thyroxine. This condition is called hypothyroidism.

What does low thyroid stimulating hormone (TSH) mean?
If your results show that you have low or normal concentrations of circulating thyroid stimulating hormone, and low concentrations of thyroxine, this may indicate a type of hypothyroidism called central hypothyroidism. Conversely low concentrations of TSH and elevated concentrations of thyroxine or triiodothyronine can indicate hyperthyroidism.


What your thyroxine (T4) results mean


Thyroxine (T4) is a thyroid hormone. Thyroxine is the inactive form of triiodothyronine. Thyroxine plays a role in a majority of the body’s cell functions such as digestion, muscle control, memory, the maintenance of strong healthy bones and brain development. Thyroxine levels can tell you a lot about your thyroid health.

What does high thyroxine mean?
High thyroxine may indicate that you have an overactive thyroid (hyperthyroidism). High thyroxine may also be caused by Grave’s disease (an autoimmune condition), hyperfunctioning nodules on your thyroid (toxic adenoma, toxic multinodular goiter, or Plummer’s disease) and thyroiditis (inflammation of your thyroid gland).

What does low thyroxine mean?
Low thyroxine may indicate that you have an underactive thyroid (hypothyroidism). Low thyroxine may also be caused by Hashimoto’s thyroiditis (an autoimmune condition), anti-thyroid medications (to correct hyperthyroidism), thyroid surgery, radiation therapy (such as that used for treatment of head and neck cancer), pregnancy, iodine deficiency and in rare cases, pituitary disorder or congenital disease (babies born with a defective thyroid or no thyroid gland).


What your triiodothyronine (T3) results mean


Triiodothyronine (T3) is a thyroid hormone. Triiodothyronine is an active form of thyroxine. Only 20% of the total volume of triiodothyronine is produced in the thyroid gland, 80% of triiodothyronine is activated in other organs in the body such as the liver and kidneys.

What does high triiodothyronine mean?
High triiodothyronine may indicate that you have an overactive thyroid (hyperthyroidism).

This may be caused by Grave’s disease (an autoimmune condition), hyperfunctioning nodules on your thyroid (toxic adenoma, toxic multinodular goiter, or Plummer’s disease) and thyroiditis (inflammation of your thyroid gland).

What does low triiodothyronine mean?
Low triiodothyronine may indicate that you have an underactive thyroid (hypothyroidism). Conditions that cause low triiodothyronine include Hashimoto’s disease and iodine deficiency.

A long term illness, severe weight loss and/or starvation may also cause low triiodothyronine. Triiodothyronine, as a biomarker is not as commonly used as thyroxine or thyroid stimulating hormone as it doesn’t always offer the full story when it comes to your thyroid health.


What your thyroid peroxidase antibodies (TPO/TPEX) results mean


Thyroid peroxidase (TPO) is an enzyme in the thyroid gland that plays a role in the production of thyroid hormones.

What does the presence of thyroid peroxidase antibodies mean?
The presence of thyroid peroxidase antibodies suggests that the cause of your thyroid condition is autoimmune in nature, examples include Hashimoto’s disease and/or Grave’s disease.

If you have high thyroid peroxidase antibodies in the blood, it means that the immune system is continuously making antibodies that attack normal thyroid gland tissue and can cause inflammation and damage the function of the thyroid.


What your thyroglobulin antibodies (TGAB) results mean


Thyroglobulin is a protein that is made by the cells of the thyroid gland. Thyroglobulin antibodies are proteins that are made by the immune system during an autoimmune attack from the body directed at the thyroid gland.

What does the presence of thyroglobulin antibodies mean?
The presence of thyroglobulin antibodies in the blood may suggest that the cause of your thyroid disorder (either hypothyroidism or hyperthyroidism) is autoimmune in nature.


If you’re reading this article, you probably want to understand what your thyroid results mean. If you haven’t, maybe you’re considering taking a thyroid test.

With LetsGetChecked, you can take a thyroid test from the comfort of home with online results available in just one week. Order today and receive complimentary clinical support as part of the service.


Written by Hannah Kingston | Medically reviewed by Gwen Murphy, PHD, MPH.