The Thyroid Gland

Where is the thyroid gland?
The thyroid gland is in the neck just behind the Adam’s apple.

What does the thyroid gland do?
Thyroid gland secretes thyroid hormone into the bloodstream sending it to every cell in the body. The body’s metabolism is slow or fast depending on thyroid hormone levels. Normal thyroid hormone levels are critical to growth, development and wellbeing from conception onwards.

What controls the thyroid gland?
The thyroid is under the control of the pituitary (the ‘master’) gland and the pituitary is, in turn, controlled by the hypothalamus. Thyroid hormone levels in the blood are constantly monitored and additional hormone is released into the blood when levels fall.

Thyroid Gland Problems and Symptoms

Underactive Thyroid (Hypothyroidism)
This is a relatively common problem. Too little thyroid hormone (aka hypothyroidism) slows the body down with resultant weight gain, constipation, aches and pains (similar to fibromyalgia), fatigue, sleepiness, mental sluggishness and poor concentration, feeling cold, hair loss, dry puffy skin (especially the calves of the legs), there may also be loss of the outer one-third of the eyebrow.

Hypothyroid symptoms in women may also include irregular, absent or scanty periods and infertility.

Overactive Thyroid (Hyperthryoidism)
This is a much-less common problem which may cause weight loss, fast heart beat, insomnia, anxiety, tremor and feeling over-heated all the time.

Hashimoto’s disease

Hashimoto’s disease is the most common thyroid disorder. In Hashimoto’s there is gradual inflammatory damage to the thyroid gland, it becomes inflamed and gradually loses its ability to appropriately secrete thyroid hormone.

Laboratory Testing for Thyroid Gland Problems
There are two thyroid hormones T3 (tri-iodothyronine) and T4 (thyroxine). In healthy circumstances when thyroid hormone levels in the blood drop more TSH (thyroid stimulating hormone) is secreted and this TSH, in turn, stimulates the thyroid to release more hormone.

Thyroid hormone exists in the bloodstream in either of two forms:

  1. ‘free’ hormone molecules which are biologically ‘active’.
  2. ‘bound’ hormone molecules which are inactive – these are hormone molecules waiting to become active.

What is usually measured when ‘standard thyroid screening blood tests’ are carried out?
Usually total T4 (thyroxine) level is checked. This result will include both active and inactive hormone levels.
Sometimes a TSH level alone may be checked.

Comments on ‘standard’ thyroid testing
My preference is to measure the active thyroid hormone levels. Hence I prefer to test both free T3 (FT3) and free T4 (FT4) along with TSH. Thyroid antibodies are also useful in indicating an evolving thyroid problem. T3 is actually much more potent than T4. Occasionally someone will have an adequate free T4 level, and normal TSH level but a low free T3 level so it really is worthwhile looking carefully at the thyroid in cases of unexplained fatigue.
If TSH alone is measured it will miss the person whose body cannot increase TSH levels in response to falling T4 or T3 levels.

What about ‘reverse T3’
Reverse T3 is similar in chemical makeup to normal T3 but it is a mirror image or isomer –think of the analogy of right versus left-hand gloves. The reverse T3 will bind to and block the ‘normal’ T3 binding site on the cell wall and prevent it from its normal activity. The clinical significance of reverse T3 is controversial – there is a suggestion that it helps to prevent weight-loss in starvation conditions such as famine. There definitely are colleagues who find measuring reverse T3 of value but I rarely check reverse T3 because there is no way directly to treat the high reverse T3 and also reverse T3 is a relatively expensive investigation

Nutrients and the Thyroid

Adequate iodine levels are important to the body’s manufacture of thyroid hormone. Iron and zinc are among the important substances in the conversion of T4 into the much-more-potent T3.

How is thyroid disease treated ?

The standard medical treatment for hypothyroidism is thyroid hormone replacement which involves a compound called thyroxine which is a synthesised form of T4. Many patients who have thyroid underfunctioning live long, happy and productive lives on T4 and never darken the door of a practice such as mine.

Armour Thyroid

There is a small percentage of patients who, anecdotally, fail to tolerate T4 well and some of them do much better taking Armour Thyroid which is pork derived, and is listed in the US Pharmacopoeia. Armour Thyroid is an extract of porcine glandular thyroid and contains both T4 and some T3. It is significantly more expensive than straightforward thyroxine/Eltroxin and that really doesn’t matter if it’s just one months treatment but over the years costs mount up. Definitely life changing for a small number of people to shift from thryxine to Armour Thyroid but I would advise considering the move carefully.

The Immune System

The commonest form of thyroid disease is hypothyroidism and the majority of this is Hashimoto’s -type autoimmune thyroiditis. I try to also, as well as organising thyroid hormone replacement, also do anything I can to rebalance the immune system because Hashimoto’s is frequently just one aspect of a larger autoimmune type response in the person’s body.

Can I get off my thyroid hormone ?

Every few weeks we get a telephone call from someone who wants to get off the thyroid hormone and stop taking it. Unfortunately for an under active thyroid thyroid hormone replacement is the appropriate, necessary and absolutely indispensable treatment. So the answer is ‘no’. That being said if someone is hypothyroid I think that they should, as part of their general treatment strategy try and lower the general autoimmune /inflammatory load in the body.

Adding in T3 Therapy
there is a minority of patients patients may need additional T3 supplementation along with normal thyroid replacement therapy due to inability to convert effectively from T4 to T3.