The Thyroid

The thyroid gland is a small butterfly-shaped gland in the neck, it weighs less than 30g or an ounce and its secretions control human body metabolism which is the way we convert food and uses energy in cells. This key controller of human metabolism and function produces four forms of thyroid hormones, three of which are known to be active molecules.

The Thyroid hormones are described as T1, T2, T3 and T4 (for simplicity). Iodine is very important as it is a component of the thyroid molecules.T3 has three iodine molecules and T4 has four. In understanding that iodine is part of the thyroid hormone you are better able to understand that it is critical for effective thyroid function. Low iodine causes the "foggy thinking" associated with low thyroid function. New Zealand soil is deficient in iodine.

If the human soul had a molecular structure, it would be a thyroid hormone. Without it our minds, the source of thought, perception, emotion, memory, imagination and love would never work and we would simply revert to uninteresting blobs on a gray landscape. T3 or tri-iodothyronine contains 80% of thyroid hormone activity and T4 or thyroxine contributes just 20% activity. T3 works in all human cells as the spark that creates metabolism. It functions in the synapse or junctions of nerves, particularly in the brain. It fires the furnaces (mitochondria) in cells, particularly in the brain. In so doing it controls our serotonin hormone which is another "feel good hormone" we rely on for emotional wellbeing. If T3 is not available to nerves then depression and anxiety with the destruction of mood and energy are invariably a consequence.

Causes of thyroid hormone deficiency

  • lack of pituitary gland stimulation in the brain
  • defective hormone manufacture in cells
  • impaired cellular conversion of thyroid hormone T4 to T3
  • autoimmune causes


  • primary hypothyroidism
  • secondary hypothyroidism
  • cellular hypothyroidism

Most estimates of the incidence of hypothyroidism are based on levels of thyroid hormones in the blood. This results in a large number of people with mild hypothyroidism going undetected.

Incidence of hypothyroidism using blood results

  • 1 - 4% of adults in New Zealand have moderate to severe hypothyroidism
  • 10 - 12% have mild hypothyroidism which steadily increases with age

    There are degrees of non performance of the thyroid gland. Sometimes we do not realise what the cause of our low energy and fatigue is. We may have multiple symptoms that represent classical thyroid deficiency, which can in the long term be life threatening, and yet we and our doctor still do not know the cause. The following is a list of some symptoms which, if you have low thyroid function, you may recognise.

    Auto-immune diseases eg coeliac's, polymyalgia
    Breast cancer
    Brittle nails
    Chronic fatigue,
    Coarse hair, 
    Cold feet and hands, 
    Difficulty in swallowing
    Diminished sweating, 
    Dry, coarse, cold, pale skin
    Excessive and/or painful menstruation 
    Heart disease and palpitations
    High blood pressure and cholesterol
    Joint pains 
    Laboured difficult breathing, 
    Loss of appetite,
    Loss of outer third of eyebrow.
    Lowered immunity
    Muscular weakness, 
    Pernicious anaemia, (B12 deficiency)
    Poor memory, 
    Poor sleeping patterns and quality
    Slow movement,
    Slow speech,
    Swelling of face and eyelids,
    Swollen feet, 
    Thick tongue, 
    Vitiligo (loss of pigment in skin)
    Weight gain,

    Diagnostic error
    Before the use of blood measurements, it was common to diagnose hypothyroidism based on basal metabolic temperature (the temperature of the body at rest) and Archilles reflex time (reflexes are slowed in hypothyroidism). With the advent of sophisticated laboratory measurement of thyroid hormones in the blood, these "functional" tests were not used. However it is now known that routine blood tests may not be sensitive enough to diagnose all cases of milder forms of hypothyroidism. As mild or subclinical hypothyroidism is the most common form, many people are going undiagnosed. The evaluation of basal temperature is probably the most sensitive functional test of thyroid function. 
    Blood results: Normal range is T4 9.0 - 19.0 Preferred range 14.0 - 19.0
                                                          T3 2.5 - 5.5 Preferred range 4.0 - 5.0
                                                          TSH 0.4 - 4.0 Preferred range <1.5

    Functional hypothyroidism 
    As early as 1959 a recognised authority on the thyroid gland A S Jackson published a paper declaring that low thyroid function is the most common disease seen by doctors and the disease most missed. Langer quotes that the situation is much the same today except that there are more tests, more misdiagnoses, and more people.

    If thyroid activity is measured by the functional temperature test as described by Broda Barnes, Stephen Langer and other medical authors, rather than blood thyroid hormone levels, the incidence is as high as 25%. There are several reasons why functional tests show a greater incidence of low thyroid than blood tests, the main reason is that blood measures T4 which accounts for 90% of the hormone secretion of a normal thyroid, this is the inactive hormone. It is T3 or tri-iodothyronine which cells make from T4 which affects cells the most. If T4 cannot be converted into T3 a person can have normal levels in the blood but be thyroid deficient. The measurement of T3 has been shown to miss 50% of patients.

    The best way to assess thyroid function is measuring its affects on the body through measurement of metabolic rate which is controlled by temperature regulation by the thyroid gland. Barnes in over 40 years of practise confirmed the original work regarding the efficacy of measuring basal metabolic temperature and thus the body's response to thyroid hormones, optimal TSH blood level is 2.0. Anything greater than 2.0 is tending to hypothyroidism. (Americian Assoc clinical Endocrinologists) Normal basal temp is 36.5, temperatures consistently lower than this indicate low thyroid function.

    Symptoms on Hypothyroidism (underactive)

  • Lethargy and fatigue
  • Unexplained weight gain
  • Decreased appetite
  • Increased sensitivity to cold
  • Slow heart rate (bradycardia)
  • Slow, weak pulse
  • Goitre (enlarged thyroid) not always present
  • Depression
  • Poor concentration and memory
  • Mental confusion
  • Low sex drive
  • Dry skin and hair
  • Ageing skin
  • Loss of hair on scalp and eyebrows
  • Constipation
  • Deeper, hoarse voice
  • Muscle weakness
  • Slow reflexes
  • Carpel tunnel syndrome
  • Muscle and bone aches
  • Infertility
  • Fluid retention
  • Puffiness round eyes

Symptoms of Hyperthyroidism (over active)

  • Rapid pulse & heart palpitations
  • Fast heart rate (tachycardia)
  • Over sensitive to heat
  • Increased sweating
  • Increased appetite
  • Weight loss
  • Insomnia
  • Anxiety, irritability, nervousness
  • Loose bowel motions
  • Hand tremor
  • Mood swings
  • Goitre not always present
  • Raised, thickened skin on tops of feet or shins
  • Fatigue
  • Shortness of breath
  • Thin, moist skin
  • Light or absent menstrual periods
  • Joint pains
  • Bulging, gritty eyes
  • Muscle weakness

Arem, Ridha (2008). The thyroid solution. New York, NY. Random House
Hertog, Theirry (2002) The hormone solution. New York, NY. Harmony
Langer, Stephen E., Sheer, James. (2006) Solved: The riddle of illness (4th Ed). USA. McGraw-Hill