Research: Mercury-Caused Endocrine Conditions
As will be documented in this paper, the majority of the population receives significant mercury exposures and significant adverse health effects are common. Mercury has been found to be an endocrine system disrupting chemical in animals and people, disrupting function of the pituitary gland; thyroid gland; parathyroid gland; thymus gland; adrenal gland; pineal gland; enzyme production processes, and affecting many hormonal and enzymatic functions at very low levels of exposure.
The main factors determining whether chronic conditions are induced by metals appear to be exposure and genetic susceptibility, which determines individual’s immune sensitivity and ability to detoxify metals. Very low levels of exposure have been found to seriously affect large groups of individuals who are immune, sensitive to toxic metals, or have an inability to detoxify metals due to such as deficient sulphoxidation or metallothionein function or other inhibited enzymatic processes related to detoxification or excretion of metals.
Thyroid gland conditions
Thyroid conditions are extremely common and adversely affect the health of millions of people, though most cases are undiagnosed. The thyroid gland secretes hormones which control the body’s metabolic rate, using iodine to create thyroid hormone. So iodine deficiency is a common cause of hypothyroid condition.
The hypothalamus secretes a hormone which triggers thyroid-stimulating hormone (TSH) from the pituitary gland to cause the thyroid gland to produce thyroxine (T4) and triiodothyronine (T3) (produced mostly T4). T4 is then converted in the body to the active thyroid hormone T3. A problem with any of these steps can cause hypothyroidism. As will be seen, toxic metal exposures such as mercury can accumulate and block or inhibit any of these necessary processes, as can other factors. Calcitonin is another hormone secreted by the thyroid gland that maintains blood calcium levels and prevents hypercalcaemia.
Effects and symptoms of thyroid deficiency include: fatigue: nervousness; depression; increased allergies; cold sensitivity; skin problems; brittle nails; weight problems; constipation; infertility; memory problems; low immune function and carpal tunnel syndrome.
Tests for thyroid deficiency include:
Standard test is blood test for TSH level (concentrations chronically above 2.0 mU/l indicate thyroid problem and cause long term health effects).
Another sensitive thyroid function test is the TRH stimulation test.
Another test is the Achilles tendon reflex test.
A good home test is the Barnes Basal Temperature Test (put a thermometer in reach of bed, before getting up take temperature under arm shoulder joint (holding tight for at least 3 minutes). Below 97.8 degrees indicates you are T3 deficient. Repeat several times.
Hashimoto’s thyroiditis is chronic inflammation of thyroid caused by an autoimmune reaction to environmental factors such as mercury or toxic metals or gluten sensitivity or milk casein sensitivity (which is commonly caused by toxic metals blocking enzymatic process needed to digest gluten or milk casein)(see later documentation).
Adrenal gland conditions
Other common hormone problems are related to the adrenal glands. The adrenal medulla manufactures adrenaline and noradrenaline (adrenaline and noradrenaline) – the fight or flight hormones. The adrenal cortex makes steroid hormones (cortisone, hydrocortisone, testosterone, oestrogen, DHEA, pregnenolone, aldosterone, androstenedione and progesterone). Some of these are also made in other parts of the body. The hormone aldosterone, together with the kidneys, regulates the balance of sodium and potassium in the body, which is commonly out of balance.
Besides imbalances of the various adrenal hormones that can cause effects, there are common chronic conditions that have been identified. Addison’s disease is chronic adrenal failure, usually related to autoimmune attack on the adrenal glands, commonly caused by toxic exposures such as mercury (see more later). It usually results in chronic hypocortisolism, resulting in inability to properly deal with stress. This also affects blood pressure, insulin regulation, inflammatory response, and metabolism of proteins, carbohydrates, and fats. Symptoms of Addison’s disease include: skin changes such as dark tanning on scars, skin folds, toes, lips, elbows, knees or knuckles.
Cushing’s syndrome is overproduction of cortisol, usually related to a tumour of pituitary or other organs. It is also commonly caused by prescription steroid hormones. Symptoms include: stomach fat, thin extremities, moon face, buffalo hump, excessive hair growth, irregular menstrual periods and infertility.
Adrenal fatigue can be caused by factors such as chronic anxiety or stress, or poor nutrition. The adrenals can become depleted leading to fatigue, weakening of immune response and disrupted sugar metabolism. Environmental toxic exposure such as mercury can block or inhibit any of the adrenal hormone processes and contribute to such conditions.
II. Common exposures to significant levels of mercury and distribution in the body
Most people with several amalgam fillings get daily exposure of mercury at levels well above U.S. government health guidelines, which amount to about 4 to 8 micrograms per day. Mixed metals in the mouth such as amalgam dental fillings, metal crowns, and metal braces have been found to result in galvanic currents in the metals which drive the metals into the saliva and tissues of the oral cavity at high levels as well as systemically, with accumulations in the brain and hormonal glands. Additionally, electric and electromagnetic fields such as those from appliances, computer monitors and power lines cause electric currents in metals in the mouth which further increase exposures to mercury and other metals.
Mercury and nickel, which are highly neurotoxic and immunotoxic, are often found at high levels in tests of those with mixed metals in the mouth and are known to commonly cause DNA damage; immune reactivity; and hormonal effects in animals and humans; including related reproductive effects.
Government health agencies in other countries such as Health Canada and amalgam manufacturers have warned against using amalgam near other metals, but this is still common in the U.S. and several other countries. Children typically also get high levels of exposure to highly toxic organic mercury compounds such as ethyl mercury through thimerosal, used as a preservative in vaccines, and to methyl mercury from fish. Warnings to ban or limit consumption of fish have been issued for over 30 percent of all U.S. lakes, including all Great Lakes, as well as U.S. river miles and bays.
Studies have documented that mercury causes hypothyroidism; damage of thyroid RNA; autoimmune thyroiditis; and impairment of conversion of thyroid T4 hormone to the active T3 form. The thyroid gland has iodine binding sites where the iodine needed for its function is obtained. For those with chronic mercury exposure the mercury occupies some of the iodine binding sites, blocking full utilisation of iodine by the thyroid, in addition to the direct damage to the thyroid since mercury is highly cytotoxic. These studies and clinical experience indicate that mercury and toxic metal exposures appear to be the most common cause of hypothyroidism and the majority treated by metals detoxification recover or significantly improve.
The estimated prevalence of hypothyroidism from a large federal health survey, NHANES III, was 4.6%, but the incidence was twice as high for women as for men and many with sub-clinical hypothyroidism are not aware of their condition. Another large study found that 11.7% tested had abnormal thyroid TSH levels with 9.5% being hypothyroid and 2.1% hyperthyroid. According to survey tests, 8 to 10% of untreated women were found to have thyroid imbalances so the actual level of hypothyroidism is higher than commonly recognised. Even larger percentages of women had elevated levels of anti-thyroglobulin (anti-TG) or anti-thyroid peroxidase antibody (anti-TP). Tests have found approximately 30% of pregnant women to have low free T4 in the first trimester.
Thyroid hormones are of primary importance for the perinatal development of the central nervous system, and for normal function of the adult brain. Hypothyroidism of the adults causes most frequently dementia and depression. Nearly all the hyperthyroid patients show minor psychiatric signs, and sometimes psychosis; dementia; confusion state; depression; apathetic thyrotoxicosis; thyrotoxic crisis; seizures; pyramidal signs or chorea occur. These hormones primarily regulate the transcription of specific target genes. They increase the cortical serotonergic neurotransmission, and play an important role in regulating central noradrenergic and GABA function.
Mercury blocks thyroid hormone production by occupying iodine binding sites and inhibiting hormone action even when the measured thyroid level appears to be in proper range. The thyroid and hypothalamus regulate body temperature and many metabolic processes including enzymatic processes that when inhibited result in higher dental decay. Mercury damage thus commonly results in poor bodily temperature control, in addition to many problems caused by hormonal imbalances such as depression. Such hormonal secretions are affected at levels of mercury exposure much lower than the acute toxicity effects normally tested, as previously confirmed by hormonal/reproductive problems in animal populations. Mercury also damages the blood-brain barrier and facilitates penetration of the brain by other toxic metals and substances. Hypothyroidism is also known to be a major factor in cardiovascular disease.
Hypothyroidism, pregnancy and breastfeeding
Studies indicate that slight thyroid deficiency/imbalance (sub-clinical) during the perinatal period can result in delayed neuropsychological development in neonate and child or permanent neuropsychiatric damage in the developing foetus or autism or mental retardation. Low first trimester levels of free T4 and positive levels of anti-TP antibodies in the mother during pregnancy have been found to result in significantly reduced IQs and causes psychomotor deficits. Women with the highest levels of thyroid-stimulating-hormone (TSH) and lowest free levels of thyroxin 17 weeks into their pregnancies were significantly more likely to have children who tested at least one standard deviation below normal on an IQ test taken at age 8 years of age. Based on study findings, maternal hypothyroidism appears to play a role in at least 15% of children whose IQs are more than 1 standard deviation below the mean ie: millions of children.
Overt autoimmune thyroiditis is preceded by a rise in levels of thyroid peroxidase antibodies. "Collectively, reports show that 30-60% of women positive for TPO antibodies in pregnancy develop postpartum thyroiditis," the researchers point out, calling it "a strong association." Without treatment, many of the women with thyroiditis go on to develop overt clinical hypothyroidism as they age and, eventually, associated complications such as cardiovascular disease. About 7.5% of pregnant women develop thyroiditis after the birth. Studies have also established a connection between maternal thyroid disease and babies born with heart defects.
Infants of women with hypothyroxinaemia at 12 weeks gestation had significantly lower scores on the Neonatal Behavioural Assessment Scale orientation index compared with other subjects. Regression analysis showed that first trimester maternal free thyroid hormone T4 was a significant predictor of orientation scores. This study confirmed that maternal hypothyroxinaemia constitutes a serious risk factor for neurodevelopmental difficulties that can be identified in neonates as young as 3 weeks of age.
Mercury (especially mercury vapour from dental amalgam or organic mercury) rapidly crosses the blood-brain barrier and is stored preferentially in the pituitary gland, thyroid gland, hypothalamus, and occipital cortex in direct proportion to the number and extent of dental amalgam surfaces, and likewise rapidly crosses the placenta and accumulates in the foetus including the foetal brain and hormone glands at levels commonly higher than the level in the mother.
Milk from mothers with 7 or more mercury amalgam dental fillings was found to have levels of mercury approximately 10 times that of amalgam free mothers. The milk sampled ranged from 0.2 to 57 mcg/l. In a population of German women, the concentration of mercury in early breast milk ranged from 0.2 to 20.3 mcg/l. A Japanese study found that the average mercury level in samples tested increased 60% between 1980 and 1990. The study found that prenatal Hg exposure is correlated with lower scores in neuro-developmental screening, but more so in the linguistic pathway. The level of mercury in umbilical cord blood, meconium, and placenta is usually higher than that in mother's blood.
Alterations of cortical neuronal migration and cerebellar Purkinje cells have been observed in autism. Neuronal migration, via reelin regulation, requires triiodothyronine (T3) produced by deiodination of thyroxine (T4) by foetal brain deiodinases. Experimental animal models have shown that transient intrauterine deficits of thyroid hormones (as brief as 3 days) result in permanent alterations of cerebral cortical architecture reminiscent of those observed in brains of patients with autism. Early maternal hypothyroxinaemia resulting in low T3 in the foetal brain during the period of neuronal cell migration (weeks 8-12 of pregnancy) may produce morphological brain changes leading to autism. Insufficient dietary iodine intake and a number of environmental antithyroid and goitrogenic agents such as mercury, soy, and peanuts can affect maternal thyroid function during pregnancy.
Mercury can have significant effects on thyroid function even though the main hormone levels remain in the normal range, so the usual thyroid tests are not adequate in such cases. Prenatal methylmercury exposure severely affects the activity of selenoenzymes, including glutathione peroxidase (GPx) and 5-iodothyronine deiodinases (5-Di and 5'-DI) in the foetal brain, even though thyroxine (T4) levels are normal. Another mechanism by which mercury exerts such effects is mercury’s effects on selenium levels which are required for conversion of T4 to T3. Gpx activity is severely inhibited, while 5-DI levels are decreased and 5'-DI increased in the foetal brain, similar to hypothyroidism. Thus normal thyroid tests will not pick up this condition.
Mercury reduces the blood’s ability to transport oxygen and essential nutrients including amino acids, glucose, magnesium, zinc, selenium, and vitamin B12 to the foetus; depresses enzyme isocitric dehydrogenase (ICD) in the foetus; causes reduced iodine uptake, autoimmune thyroiditis, and hypothyroidism. Because of the evidence of widespread effects on infants, the American Association of Clinical Endocrinologists advises that all women considering becoming pregnant should get a serum thyrotropin test so that hypothyroidism can be diagnosed and treated early. Since mercury and toxic metals are common causes of hypothyroidism, another test that should be considered is a hair element test for mercury or toxic metal exposures and essential mineral imbalances.
Studies have also established a “clear association” between the presence of thyroid antibodies and spontaneous abortions. Levels of recurrent abortions in a population with positive levels of thyroid antibodies in one study were 40%, 5 times the normal rate. Hypothyroidism is a well documented risk factor in spontaneous abortions and infertility. Another study of pregnant women who suffer from hypothyroidism (underactive thyroid) found a four-times greater risk for miscarriage during the second trimester than those who don’t, and women with untreated thyroid deficiency were four-times more likely to have a child with a developmental disabilities. Mercury through its affects on the endocrine system is also documented to cause other reproductive effects such as infertility, low sperm counts, abnormal sperm, endometriosis, PMS and adverse effects on reproductive organs ... (continued - see below)
This article is a SAMPLE of a fully referenced research PDF available by clicking Mercury-Caused Endocrine Conditions. Many other research papers are also available on the Research page.
For an in-depth explanation of the effects of mercury on the endocrine system, please refer to The Natural Recovery Plan book.