The thyroid is a small gland located in the neck and is responsible for producing hormones that regulate the rate at which our cells utilize the fuel that we take in from our diet. These thyroid hormones can have a major impact on how we feel on a daily basis. A dysfunction in this gland can lead to a wide array of negative signs and symptoms.
The following are a few signs & symptoms of low thyroid production (hypothyroidism):
* weight gain
* puffy face
* decreased sexual interest
* cold intolerance
* cold hands and feet
* brittle nails
* swollen legs, feet, hands or abdomen
* rough dry skin
* menstrual irregularities
Thyroid hormones can have a major impact on how we feel on a daily basis.
TSH (thyroid stimulating hormone) is actually not a thyroid hormone but a pituitary hormone that does exactly what the name implies; it stimulates the thyroid gland to produce thyroid hormones.
Most doctors will simply look at this number by itself and if the patient falls within the large reference range of .27 – 4.5 mIU/L, they are considered “normal.”
In my practice I use the person’s clinical signs and symptoms first and foremost and the lab values second to determine the status of a person’s thyroid function.
When looking at TSH values, you need to know that the higher the number is, the more sluggish the thyroid is working and the lower the number the more optimal in most cases.
The optimal TSH range that I see in healthy patients is .27-1.5 mIU/L, and where they need to be within that range depends essentially on how they feel clinically.
For example, a person presenting with fatigue, hair loss, constipation, and depression may have a resolution of some of their symptoms when their TSH gets to 1.5 mIU/L but not until their levels reach .5mIU/L do we see all those symptoms improve completely if they are, in fact, related to low thyroid function.
Free T4 and Free T3 – These are 2 separate tests, but we will discuss both together.
T4 is the dominant form of thyroid hormone produced by the thyroid gland, but it’s actually considered to be a storage form of thyroid hormone and is essentially inactive until it gets converted in our tissues to T3.
Looking at both of these values together is important in determining how well your thyroid hormones are functioning at the level of the cell.
Our TSH level, as discussed in Part 1 of Blood Testing For Thyroid Metabolism , is a pituitary hormone and its secretion is determined by how much actual thyroid hormone is floating around in the blood.
Ideal range for Free T4 is in the middle of the reference range and up, (.27-4.5 mIU/L. ) and the ideal range for Free T3 is within the upper 75th percentile of the reference range.
This is Part 3 of our discussion on Blood Testing For Thyroid Metabolism
Reverse T3 – This thyroid hormone needs to be analyzed along with Free T3. (Free T3 is discussed in more detail in Part 2 1 of Blood Testing For Thyroid Metabolism)
Reverse T3 is a blocking hormone that is produced from T4 and actually slows down the metabolism.
I tell my patients that T3 is like the body’s gas pedal and reverse T3 is like the brake pedal.
We need to have a proper balance between these two hormones in order for our metabolism to function optimally.
There are many factors that can contribute to elevated reverse T3,
increased levels of stress hormones
Ideal range for reverse T3 is to look at the ratio between free T3 and reverse T3. The reference range that most labs give for reverse T3 is 8-25 ng/dl and 2.3-4.2 pg/ml for free T3.
As you can see both markers are in different units of measure so what I do is simply move the decimal point of the free T3 ranges and make them 23-42 then assess the ratio between free T3/reverse T3.
The ideal ratio is 2.5 or greater. This ratio tends to correlate very closely to the person’s clinical signs and symptoms.
Thyroid Antibodies (thyroid peroxidase and thyroglobulin antibodies) – This is the last of the thyroid tests that I typically recommend AND concludes our 4-Part Series on Blood Testing For Thyroid Metabolism.
The presence of either antibody in the blood is an indication of an autoimmune disease affecting the thyroid called Hashimoto’s thyroiditis.
The actual antibodies can also interfere with how the thyroid hormones interact at their cellular receptors.
The optimal range for both should be zero.
As I stated above, it’s important to run the proper lab testing to assess your thyroid function and determine your thyroid metabolism, but identifying clinical signs and symptoms of hypothyroidism takes precedence.
This is because they may provide clues to an underlying thyroid issue far sooner than it’s revealed on a blood test.
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