Thyroid Hormone Profile

Thyroxine (T4) and Trilodothyronine (T3) are produced by the thyroid gland and are essential for the growth and development of the human body. T3 and T4 govern the body's metabolic rate, nervous system and heart functions.

The thyroid is among the largest glands of the endocrine system and weighs between 15 to 20gms. In shape it looks a bit like a butterfly with two lobes connected by a band of thin tissue. Thyroid disorders are among the most common diseases affecting the endocrine system. Studies have shown that in the developed world, between 3 and 4 percent of the population suffer from thyroid problems. In general women are more prone to thyroid problems and since thyroid function decreases with age, it is most prevalent among menopausal women.

The thyroid's main function is to absorb iodine present in food and convert it into T4 and T3. The cells in the thyroid gland are the only ones that can absorb iodine and if they do not function properly, the body has no redundancy system to take over this job. The cells mix the iodine with an amino acid called Tyrosine to make the T4 and T3 which are then released into the bloodstream which transports them throughout the body.

Every cell in the body is dependent of the thyroid hormones to control their metabolism. The production of these hormones by a healthy thyroid gland is in the ratio of 80% of T4 to 20% of T3. However, this difference in quantity is balanced by the fact that T3 is the "stronger" of the two hormones.

The functioning of the thyroid gland itself is controlled by another gland called the pituitary gland. This gland is small, about the size of a peanut and is located at the base of the brain. When the pituitary gland sense that the levels of T4 and T3 in the blood are at too low a level to control the body's metabolism, it produces the Thyroid Stimulating Hormone (TSH) which stimulates the thyroid to produce more T4 and T3. Once the production of T4 and T3 have increased and their levels in the bloodstream have reached the required levels, the pituitary gland senses this and decreases its production of TSH which in turn reduces the stimulation of the thyroid gland and consequently, the production of T4 and T3.

The pituitary gland in turn is regulated by the hypothalamus gland, which lies in another part of the brain. The hypothalamus produces the TSH Releasing Hormone that allows the pituitary gland to produce the TSH when needed.

If all this sounds complicated, the best way to understand it is to look at the pituitary gland as a kind of thermostat like that of an air-conditioner and T4 and T3 as the cold air. Just as the thermostat cuts in when the room gets too warm and increases the flow of cold air, the pituitary cuts in when the T4 and T3 levels in the blood get too low. And just as the thermostat cuts out when the room is cold enough, the pituitary gland cuts out when the T4 and T3 levels in the blood have reached the correct levels. Using the same analogy, we can look at the hypothalamus as the hand that sets the thermostat and decides what are the minimum and maximum temperatures (or levels of T4 and T3) that are required.

Besides inadequate iodine intake, another factor that affects the functioning of the thyroid gland is the amount of pollutants in the atmosphere. Scientific tests have established that continued exposure to toxins and metal in the atmosphere, which are absorbed by the body, can impair thyroid function.

Symptoms of an underactive thyroid gland (Hypothyroidism) include:

- Weakness and general lethargy
- Dry and coarse skin, often accompanied by itching
- Slow or indistinct speech
- Oedema (heaviness or swelling) of the eyelids
- Weight gain
- A thick tongue
- Cold and / or clammy skin
- Below normal levels of perspiration

An overactive thyroid usually shows itself by the following symptoms:

- Fatigue and general loss of energy
- Shaking of the body, particularly the limbs
- Restlessness
- Unusual thirst
- An unusual intolerance to heat or even warmth
- Increased levels of perspiration
- Trembling of the tongue

The Thyroid Hormone Profile is a test to see how well the thyroid gland is functioning in producing T3 and T4. This test is easily performed by a patient in the comfort of his home. The test measures the amount of unbound free hormones, or those available for controlling the body' metabolism, and provides a true picture of the body's metabolic function.

Upon obtaining the request form from a medical practitioner, a person may buy the Thyroid Hormone Profile test kit from a drug store or order it online from a manufacturer. While each manufacturer will have a kit of their own design, the basics principles of the test remain the same. The kits come with detailed instruction on how the test is to be performed. All that is really required is a small ample of blood and the kit will contain everything required for obtaining and storing the sample.

The blood sample may be taken at any time of the day and there are no restriction requiring either fasting or having eaten a specified time before taking the sample. The only restriction is that the test should not be taken by anyone with blood clotting disorders such as haemophillia or by those taking blood thinning medication such as anti- coagulants or even those who regularly consume aspirin for other medical reasons. If a person with any of these problems requires the test, it should be done under medical supervision.

The blood sample is stored in a container that comes with the kit and must be sent the manufacturer, either directly or though a doctor depending on the company's policy, who will conduct the blood analysis and revert with the results. Again, depending on the company, the results are usually available within a week to ten days. Once the results are obtained, the doctor can advise the patient on what treatment, if any, may be required.