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.
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.
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:
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.
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.
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.If a carefully-diagnosed hypothyroid patient feels worse when thyroid treatment is commenced
Some individuals will report actually feeling much worse rather than better when their underactive thyroid is treated. Typical complaints may include anxiety,palpitations, insomnia and feeling ‘wired’. This may be due to ‘weak’ adrenal glands. Commencing to treat the adrenals before beginning thyroid treatment usually solves this problem.
Some patients may need additional T3 supplementation along with normal thyroid replacement therapy due to inability to convert effectively from T4 to T3.
Some patients may not tolerate synthetic thyroid preparations well and may wish to ‘try’ Armour Thyroid (this is a pork-derived thyroid gland preparation which is in the US pharmacopeia).
Veronica (Dublin 14)