Know Your Thyroid Hormones and Their Healthy Ranges

Getting to know the Thyroid Hormones

TSH stands for Thyroid-Stimulating Hormone and is also known as Thyrotropin. TSH is released by the pituitary gland to stimulate the enzyme thyroid peroxidase (TPO). TPO is made in the thyroid gland and combines iodine with hydrogen peroxidase to create thyroid hormones.

Thyroxine, more commonly known as T4, is one of the hormones produced by the thyroid gland. It is called T4 because it contains four molecules of iodine attached to one protein called thyroglobulin. About 93% of the hormones made in the thyroid gland consist of T4.

Triiodothyronineis given the name T3 because it has three molecules of iodine attached to the thyroglobulin. T3 makes up roughly 7% of the total hormones produced by the thyroid gland. Since this is the predominant thyroid hormone that the body uses, it must be made from other sources. The intestines convert about 20% of T4 into T3, but only in the presence of enough gut bacteria. The liver also converts T4 to T3 through conjugation pathways as well as many other cells in the body containing enzymes to spark this conversion.

Healthy Ranges of Thyroid Hormones

Laboratory ranges are not the same as functional health ranges for levels of sugar in the blood.

The numbers for normal levels of thyroid hormones in the blood are categorized into two sets. One is the standard procedure, which is the laboratory ranges viewed in the lab reports. The second is the functional range. For normal levels of thyroid hormones in the blood, the laboratory ranges are normally wide while those of functional ranges are fixed. So, what is the difference?

Laboratory ranges for normal levels of sugar in the blood are obtained from numerous labs that collect a vast array of tests. These results are normally averaged to obtain the ranges, but healthy people often don't have labs done which is a disadvantage of this process. It's typically unhealthy people who go to have labs done which means the ranges obtained are usually from these people.

If healthy people get to be averaged by the labs, then functional ranges would be obtained. The healthy functional ranges of thyroid hormones are listed below:

TSH:1.5 - 3 microunits/mL.

Thyroxineis measured in two forms:

Total T4: 5 - 12 mcg/dL

Free T4: 0.8-2.4 ng/dL.

Triiodothyronineis also measured in two forms:

Total T3: 60-181 ng/dL

Free T3: 230-420 pg/dL

Thyroid Nodules

Multi-nodules on the thyroid can be further classified as toxic or non-toxic depending on the secretion of thyroid hormones; if they are toxic then they would be secreting too much thyroid hormone in which thyrotoxicosis could occur and if they are non-toxic then that would mean that the nodules do not secrete too much thyroid hormone.

Non- toxic nodules and/or goiter may be treated if compression takes place or for cosmetic reasons. The typical management for toxic goiter/toxic nodules includes anti-thyroid medications, partial or complete thyroidectomy, and/or radioactive iodine, depending on the patient's age and clinical status of the gland.

While prescription thyroid hormones might bring lab levels back to normal, most often this does not address the reason why the thyroid faltered in the first place.

Depending on whether or not the nodules are toxic must be taken into account. It is essential to remember that there are reasons why thyroid nodules form in the first place; investigating possible mechanisms is essential to overall health. Thyroid hormones affect other systems in your body and, in return, other systems affect thyroid function.