Many people are asking if they have a thyroid problem. Their hair is falling out, they suddenly become sensitive to certain foods, they always have cold hands or they have gained weight without any apparent reason.

What is the normal thyroid levels range

There are “normal lab values” for blood tests results, but there are also “optimal” ranges which actually tell you far more about your thyroid. My basic thyroid levels (TSH, T3, T4) have always been in the “NORMAL” range. However, when I was sick, they were not in the “OPTIMAL” ranges. Below is a list of functional/optimal ranges for thyroid markers. If your results are outside these levels, you should definitely start treating your thyroid levels.  so you can start feeling better.

I have written about my recommendations for a good endocrinologist in my other post.

Take your latest blood test results and compare to the chart below:

Chart of normal and optimal thyroid TSH levels.

Chart of normal and optimal thyroid TSH levels.

Why are T4 and T3 levels important?

The function of the thyroid gland is to use, convert iodine into thyroid hormones: 

Thyroxine (T4) and Triiodothyronine (T3).

Thyroid cells are the only cells in the body which can absorb iodine. These cells combine iodine and the amino acid tyrosine to make T3 and T4. T3 and T4 are then released into the blood stream and are transported throughout the body where they control metabolism (conversion of oxygen and calories to energy).

The whole human well-being is depended on thyroid hormones.

The thyroid gland is the sole source of T4 and the source of only 10 to 20% of T3. The remaining 80 to 90% of T3 comes from conversion of T4 to T3 by organs such as the liver, kidneys, brain, and skin. In other words, the body itself breaks down T4 to produce the amount of T3 it needs.When a patient begins to take levothyroxine, the level of T4 rises and becomes stable over a five-week period. From then on, the level of T4 in the blood changes very little after each pill—the level of T4 is slow to rise and slow to fall.

On the other hand, when a patient regularly takes T3, the level of T3 in the blood tends to rise and fall rapidly over a period of hours after each pill. In addition, since T3 is much more potent than T4, a patient may experience symptoms of hyperthyroidism for several hours after taking a substantial dose of T3.

Indeed, patients taking thyroid hormone preparations containing substantial amounts of T3 may prefer them to preparations containing only T4. Their reasons vary, but many patients say that it is easier to maintain their weight and that they have more energy when they take this combination of thyroid hormones. However, these benefits may come at a price—patients are often hyperthyroid for several hours each day. Hyperthyroidism predisposes these patients to osteoporosis, heart rhythm disturbances, and, possibly, a shorter life span. Substituting one disease for another is not desirable.

Commercially available thyroid hormone preparations made from animal thyroid glands invariably contain T3 and, as noted above, should not be used. Another reason to avoid these animal thyroid hormone preparations is the difficulty in preparing tablets that have exactly the same amount of thyroid hormones in each tablet. On the other hand, brand-name synthetic levothyroxine generally can be relied upon to have the stated amount of T4 in each tablet.


Optimal Lab Values-how to interpret your results

Thyroid Function Tests: Normal Ranges. – Normal Laboratory Values