Hypothyroidism Testing

What is Hypothyroidism?

Hypothyroidism is one of the most common thyroid problems in the United States.  At greatest risk are women, older individuals (over 60 yrs) and those with a family history of thyroid conditions.  Hypothyroidism is a condition where the thyroid does not produce enough thyroid hormone.  Resons for this can range from low iodine and selenium to heavy metal toxicity and a variety of other issues.
Testing for Hypothyroidism
Allopathic doctors will diagnose a thyroid problem on the basis of the TSH test. TSH stands for thyroid stimulating hormone.  This hormone is not a thyroid hormone but a pituitary hormone.  TSH stimulates the thyroid to produce T4 and T3.  Because this is not a thyroid hormone many holistic and integrative doctors prefer to use the Free T4 and Free T3 tests as a marker.

These are common tests to check thyroid function & what they mean:

TSH – Thyroid Stimulating Hormone – a pituitary hormone that stimulates the thyroid gland.  The TSH receptors are found on the follicular cells of the thyroid. Stimulation of these receptors increases T3 and T4 production and secretion.

T3 – Triiodothyronine – a hormone that helps regulate growth and development, helps control metabolism and body temperature, and, by a negative-feedback system, acts to inhibit the secretion of thyrotropin by the pituitary gland. Triiodothyronine is produced mainly from the deiodination of thyroxine in the peripheral tissues but is also synthesized by and stored in the thyroid gland as an amino acid residue of the protein thyroglobulin. Triiodothyronine circulates in the plasma, where it is bound mainly to thyroxine-binding globulin and thyroxine-binding prealbumin, proteins that protect the hormone from metabolism and excretion during its half-life of 2 days or less before it is degraded in the liver. The hormone is the most active thyroid hormone and affects all body processes, including gene expressions.{1}

Free T3 – This is the free (unbound form) of T3.  It is believed that only this form of T3 is responsible for biological action such as energy and metabolism.  In many hypothyroid conditions you will see low values of this hormone.  The values can even be in the range and still be considered low when other clinical signs are present.  Most seem to feel best in the upper 1/3 of the ranges.  To determine this take the high number of the range and subtract the low number.  Take that number and divide by 3 then multiply that number by 2.  Take that number and add it to the lower number of the range.  This will give you the low number of the new upper 1/3 range and the upper end of the lab range is the high end.

T4 – 99.95% of this hormone released from the thyroid is protein bound – mainly to the thyroxine binding globulin (TBG).  The half life of this hormone once released into the blood stream is about 6 days.  This is the precursor to the active T3 hormone.  Conversion of this hormone to the T3 hormone occurs in the kidney and liver.  If your liver or kidney is compromised by heavy metals or other environmental toxins or even toxins in your food such as preservatives the ability to convert effectively will be compromised.  In many cases a good liver and kidney cleanse can increase the level of active thyroid hormone.  Maintaining a clean /organic whole foods diet will help as well.

Free T4 – The Free T4 test is a newer test.  It is not effected by protein level in the blood as the T4 only test is.  Since the Free T4 hormone is the active form of thyroxine many consider this test a more accurate reflection of the thyroid hormone function. In most cases it has been used as a replacement to total T4 by many doctors.

Thyroglobulin – This test measures the thyroglobulin protein in the blood stream. It is used in the thyroid hormone creation process by binding to tyrosine and iodine.  Thyroglobulin levels are elevated when iodine deficiency is present.  It is also used for those who have had a thyroid cancer diagnosis and have received a thyroidectomy and radioactive iodine treatment (RAI).  Only normal thyroid tissue and thyroid cancer tissue will produce this protein.

Comment from site owner:  The problem I believe with using this as a marker for recurrent cancer is that iodine deficiency in many cases causes iodine resistant tissue.  The receptors shutdown (aka go to sleep) due to lack of iodine passing by them to be brought into the cells. The tissue may not take up RAI but will continue to produce Tg.  It may in fact not be cancerous tissue at all but just iodine resistant.  The doctors will continue to hit you with more RAI and external beam in an attempt to eradicate cancer that may not even be there.  This does nothing more than kill your immune system and spiral you closer to death.  This is the condition I faced with Tg levels of 24 after 3 RAI’s.  I have negative RAI scans as well.  I opted no treatment with more radiation.  Just natural therapies to heal my body of the underlying causes of cancer.  My Tg is now 13.

Thyroglobulin Antibodies (Tg Ab) – This is a measurement of antibodies that the body has created against the thyroglobulin.  Thyroglobulin is used in the iodine / tyrosine binding process to form thyroid hormone.  A positive test result for these antibodies is an indication of autoimmune thyroid disease.  In the case of thyroid cancer when these antibodies are present the thyroglobulin level is not accurate and testing of the Tg level must be done by a special laboratory.

Thyroperoxidase antibody  (TPO Ab) – This is a measurement of antibodies against the Thyroperoxidase enzyme.  The TPO enzyme is expressed in the thyroid by liberating iodine for binding to tyrosine residues on thyroglobulin for the production of thyroxine (T4) and triiodothyronine (T3) hormones.  Testing positive for these antibodies is an indication of an autoimmune thyroid condition.