Elk River Chiropractor | Elk River chiropractic care | MN | Free T4

                      Dr. John W. Larson, DC                          Phone:  763-241-5436

                      200 5th Street NW                                       Fax: 763-241-5466

                      Elk River, MN  55330                 service@HealingChoices.com

Free T4
 
Elk River Chiropractor | Elk River chiropractic Free T4 |  MN |

Thyroid Lab Tests:

Why testing T4 is NOT the best measure of your thyroid hormone levels

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Free T4 is one of our 6 Critical Thyroid Lab Tests.  (To see a list of all 6 click here.)  Testing T4 is the 2nd most common measure of thyroid function (after TSH) by the medical profession.  This lab test is used by medical providers to determine the amount of thyroid hormone in your body . . . especially for the millions of people taking thyroid medication.  Ironically . . . Testing T4 is NOT the best lab test to measure of the amount of active thyroid hormone in your body.

A Little More Background on theThyroid (in case you missed this from the prior article)

A thyroid problem is associated with many symptoms.  In fact, the thyroid has the nickname of the "great mimicker" because poor thyroid function can cause so many different symtoms and mimic many other health conditions.  Some people go from one doctor to another trying to find out what is causing their symptoms . . . only to eventually find out that their poor thyroid function is playing a major role in why they don't feel as good as they used to.

Your thyroid is located in the front of the neck just below your Adams apple.  Many people describe the thyroid in the shape of a butterfly with the "wings" of the thyroid extending to both sides a wrapping around the windpipe or trachea while still being connected in the middle by a small band of thyroid tissue (called the isthmus) in the front of the windpipe.  This is where a doctor will feel for your thyroid gland to see if there are any lumps or if anything feels abnormal about your thyroid gland.

What is T4 and what is the difference beweteen Total T4 and Free T4?

T4 is one of the many forms of thyroid hormone in your body.  When your thyroid gland is stimulated to produce thyroid hormone . . . your thyroid gland produces mostly the form of thyroid hormone we call T4 . . . also called Thyroxine.  It is called T4 because there are 4 iodine molecules attached to the hormone complex.

Your thyroid produces far more T4 than T3 in about a 20 to 1 ratio . . . meaning 20 particles of T4 hormone for every 1 particle of T3 hormone.  The problem with relying on T4 as a measure of the amount of thyroid hormone in your body is that T4 has very little biological activity compared to the more bio-available form of thyroid hormone we call T3.  This means that T4 has very little effect in stimulating the metabolism of your cells, and very little effect on determining the metabolism of your entire body.

T4 - like most hormones in your body - exists in both a bound (inactive) form, and an unbound (active) form.  When a lab test is measuring the Total T4 levels it is measuring the total of inactive + active forms of T4.  Because your body can only use a hormone when it is available in the unbound (active) form . . . what we also call the "Free" form . . . it is far more useful to know the levels of the active form of a hormone . . . this makes Free T4 the best measure of T4 levels.

Again . . . it is critical for you to understand that Free T4 is worth including in a thyroid lab test, but it has limited value in determing if you are at good thyroid hormone levels and if your metabolism is functioning at optimal levels.  A thyroid lab test that includes only TSH and Free T4 can be misleading because these levels can be in the normal or optimal ranges, and you could still have a thyroid problem revealed when doing all 6 of the critical thyroid lab tests recommended in these articles.

What does the Free T4 lab result mean?

Let's first take a look at the reference ranges for this lab test.  Keep in mind these reference ranges many vary slightly from one lab to another, and the reference ranges shown below are in Standard U.S. Units (not Standard International Units) but a common range provided by the lab will look like this:

Free T4:  0.82 - 1.77

Also keep in mind that most labs will provide a reference range on their lab report that is very wide range, and does not represent what is actually considered an optimal level indicating the best function of your thyroid.  A more critical evaluation of the Free T4 lab test will look like this:

 

 

 

 

 

 

Looking at a lab result for more than what is simply a Clinical High or Clinical Low result is referred to as "Functional Lab Testing".  This requires one to consider what is truly an Optimal range . . . meaning it is the best range for Free T4 to be in for optimal thyroid function.  It also considers a Functional High and Functional Low range . . . meaning it is starting to move in the wrong direction and a person is likely starting to feel some symptoms of poor thyroid function even though it is not yet in the clinical high or low range.  Here's what you want to be thinking about for each of these reference ranges:

Free T4 at Clinical High (1.78 or higher)This indicates an obvious overactive or hyperthroid function (hyperthyroidism) and there is likely too much thyroid hormone in your system to be healthy.  With Free T4 in the Clinical High range a person would likely receive a clinical diagnosis of Hyperthyroidism.  Usually this is in response to taking a thyroid medication dose that is too high, or the thyroid has become overactive in response to an auto-immune condition . . . but could be due to other problems as well.  If an auto-immune thyroid condition is discovered, then the goal is to reduce the auto-immune reaction using dietary and nutritional strategies - which can be very effective.  If a medication dose is too high, then the prescribing doctor will need to reduce the daily dose of the medication.

Free T4 at Functional High (1.57 - 1.77)While many health providers will dismiss this as being within the labs reference range of "normal".  The reality is that some people may be suffering with the symptoms of an overactive or hyperthyroid function when their Free T4 levels are testing in this range, but this sould first be compared to other thyroid lab test   Free T4 will often be in this range for two reasons:  1) they are on a thyroid medication and their medication dose is just a little too high, or 2) their thyroid function is starting to go into overdrive - often in response to an auto-iummune condition which can be confirmed by testing the thyroid antibodies in lab testing (Thyroid Peroxidase Antibody or TPO and Thyroglobulin Antibody).  If an auto-immune thyroid condition is discovered, then the goal is to reduce the auto-immune reaciton using dietary and nutritional strategies - which can be very effective.  If a medication dose is too high, then the prescribing doctor will need to reduce the daily dose of the medication.

Free T4 at Optimal (1.03 - 1.56):  This is considered the optimal range for Free T4 indicating you have the best or optimal function of your thyroid.  Keep in mind that what is considered the Optimal range may vary slightly when you are working with a doctor that specializes in Functional Lab Testing.  This slight difference of opinion on what the Optimal range should be is often based on the differences in the experience and training that doctors receive over their years of helping people, but the Optimal range among all Functional Medicine Doctors is likely near the suggested range shown here of 1.03 - 1.56.

Free T4 at Functional Low (0.82 - 1.02)While many health providers will dismiss this as being within the labs reference range of "normal".  The reality is that many people are suffering with the symptoms of low thryoid function when their Free T4 levels are testing in this range.  I will often tell my patients to think of this as a "pre-hypothyroid" range.  Just like a person can be pre-diabetic . . . you will want to take action and make changes before they become a full diabetic.  The same is true of your thyroid . . . many people are pre-hypothyroid and we want to take action to improve this before it gets worse and becomes a full hypo-thyroid condition.  I have seen with my own patients that the right natural or nutritional therapies can work very well to improve thyroid function when the Free T4 is in the Functional High range, and will often bring the Free T4 lab test back into the optimal range.

Free T4 at Clinical Low (0.00 - 0.81)This indicates an obvious low throid function (hypothyroidism) and there is likley not enough thyroid hormone in your system to be healthy.  With Free T4 in the Clinical Low range a person would likely receive a clinical diagnosis of Hypothyroidism, and then be prescribed some type of thyroid medication from their medical provider.  Keep in mind that there are many things that can be done from a natural or nutritional prespective that can help improve how your own thyroid gland is functioning.  It may not eliminate the need for a thryoid medication, but it can reduce your dependence on this medication by helping your own thyroid function the best it can.  If you are already on thyroid medication then your medication dose is too low, or you may do better on a different thyroid medication.

In summary . . .  keep in mind that Free T4 is still an important test to be doing as part of a thyroid testing lab panel, but always remember that Free T4 does have its limitations and Free T4 can be in labs normal range - even in the Optimal range - and you may still have a thyroid problem when doing a more detailed lab testing of thyroid function.

Be sure to share this information with family and friends who have been diagnosed with a thyroid problem, or the people you care about who are suffering with symptoms of a thyroid problem.  The rest of the information on the 6 Critical Thyroid Lab Test will be coming soon!

Your partner in Health and Happiness,

Dr. John W. Larson, DC

Clinical Nutrition and Hormone Health Expert

service@HealingChoices.com

763-241-5436

 

 
 
 
Healing Choices - Natural Healthcare     200 Fifth Street NW     Elk River, MN  55330  
Phone: (763) 241-5436     Fax: (763) 241-5466     Email:  service@HealingChoices.com

Disclaimer:  This information has not been evaluated by the Food and Drug Administration.  The information should be considered opinion and for educational purposes only.  Nothing on this webpage or website is intended to diagnose, treat, cure or prevent any disease.