The Thyroid Gland
The thyroid gland is located immediately below the larynx and a butterfly-shaped organ, just in front and on both sides of the trachea. The right and the left lobe are connected by a small middle lobe, called thyroid isthmus.
Aprox 50% of the earth’s population have an over-sized thyroid gland and about a third of the population have additional changes that make a thyroid therapy necessary. Especially during pregnancy, but also after having reached the age of 30, regressive-degenerative changes with calcification, nodular and partly regressive-cystic transmutations may occur.
The thyroid gland’s function is to supply the organism with the thyroid hormones L-Thyroxin = L-T4 and L-Triiodothyronine = L-T3. The micro-element Iodine, is the heaviest and also a most essential component of thyroid hormones.
Thus changes in the daily iodine dose, supplied through nutrition, have great influence on the thyroid gland’s function and morphology (structure). According to calculations of the WHO (World Health Organisation) an average adult needs between 150 to 250 µg iodine per day.
Iron / Ferritin
An important enzyme for the thyroid hormone production is Thyroxineperoxidase. This key enzyme for hormone synthesis is not produced sufficiently during a period of iron deficiency. Hence, the Ferritin level and therefore the iron supply should always be controlled.
In addition to iodine, iron becomes particularly important to keep up the usual thyroid functions. Iron is an essential component of thyroidperoxidase. In one of his publications Gärtner showed that women with an iron deficiency (Ferritin level below 30 μg/l) have a significantly low FT4 and FT3 at a slightly high TSH level. Further tests considering children showed that under an iron deficiency (Ferritin level below 20 μg/l) an iodine substitution does not lead to a reduction of the struma. Far more a reduction only occurs after balancing this iron deficiency. This has a high clinical significance, as Gärtner says, because Ferritin is not part of the routine diagnostic of thyroid malfunctions. As new consolidated findings prove, such a therapy definitely must be considered, as particularly young women often show an iron deficiency in addition to a low iodine level. At a Ferritin level below 30 μl, the iron deficiency should be solved as well to achieve a well-working Struma prophylaxis or Struma therapy (Zimmermann et al in Thyroid 12: 867-78, 2002).
The thyroid gland is the only gland, which – possibly as a mechanism of adjustment to the irregular iodine supply – is capable of storing great amounts of hormones, so that the stock lasts for about two months.
The thyroid gland synthesizes hormones into the blood cycle according to the current body need. Thus the thyroid gland daily synthesizes about 100 μg of L-T4. L-T3 is only secreted in small amounts, as it is mainly produced from L-T4 outside the gland through influence of the enzyme-type-I-5/-Dejodase.
This Dejodase can, considering genetic abilities, can work at significantly lower rate, which finally leads to a more or less strongly revealed deficiency of the usual very effective L-T3 hormone. This fact currently has become focus of many scientists considering weight problems. Dejodase secretion can be stimulated through Selenium supply.
The thyroid hormones influence (L-T3 ten-times as potent as L-T4):
– Carbohydrate metabolism
They lead to an increasing rate of the intestinal absorption of carbohydrates, an increase in the rate of gluconeogenesis and to a raise in carbohydrate breakdown. This supports the effect of insulin, although at the same time insulin increasingly disintegrates, so that the insulin demand generally rises.
They lead to an increase in fat mobilisation and breakdown of stored fats, but also to a slightly higher lipid synthesis. Hence, in case of a hyper-activity (Hyperthyreosis) the cholesterol level decreases, whereas in case of a hypofunction (hypothyreosis) the cholesterol level increases.
At normal concentration levels they have an anabolic effect. At increased hormone concentrations (hyper-function) there is a catabolic (deconstructing) effect.
– Bone Metabolism
Only through a sufficient supply of thyroid hormones can the skeletal system develop ideally. A deficiency in supply may lead to a disproportional lower growth (dwarfism). Within adults thyroid hormones at normal concentration level effect the activation of bone construction (Osteoblasts).
The predominance of bone deconstruction in case of a hyperthyreosis (hyper-function) may lead to a loss of bone substance (Osteoporosis).
– Central Nervous System (CNS)
The neuro-muscular transmission and muscle structure: Thyroid hormones are most essential to achieve normal brain development, as hormone deficiencies during pregnancy may lead to irreversible damage, but the adult may also suffer from changes in the central nervous system, tendon reflexes and muscle system, caused through a hormone under- or overproduction.
Thyroid hormones influence the whole intermediate metabolism and have a major significance for the normal function of gonads (reproductive organs) and a majority of other physiologic processes.