Hypothyroidism

Hypothyroidism is a condition caused by abnormally low thyroid hormone production. There are many disorders that result in hypothyroidism. These disorders directly or indirectly involve the thyroid gland.

It is a condition in which the thyroid glands fail to function adequately, resulting in reduced levels of thyroid hormones in the body. Cretinism is a type of hypothyroidism that occurs at birth and results in stunted physical growth and mental development.

Severe hypothyroidism is called myxedema.

Hypothyroidism, like hyperthyroidism, probably also results in most instances from autoimmunity against the thyroid gland, but immunity that destroys the gland rather than stimulates it. The thyroid glands of most of these patients have ‘thyroiditis’ which means thyroid inflammation. This causes progressive deterioration and finally fibrosis of the gland, with resultant diminished or absent secretion of thyroid hormone. Several other types of hypothyroidism also occur, often associated with development of enlarged thyroid glands, called thyroid goiter.

Complete lack of thyroid secretion usually causes the basal metabolic rate to fall 40 to 50 percent below normal, and extreme excesses of thyroid secretion can cause the basal metabolic rate to rise to 60 to 100 per cent above normal.

What are the thyroid hormones

Thyroid secretion is controlled primarily by thyroid stimulating hormone (TSH) secreted by the anterior pituitary gland.

Thyroid hormones are produced by the thyroid gland. The thyroid gland uses iodine (usually available from the diet in foods such as seafood, iodized salt, cheese, yogurt, egg etc.) to produce thyroid hormones. To form normal quantities of thyroxine, about 1mg of ingested iodine in the form of iodides are required each week. To prevent iodine deficiency, common table salt is iodized with about 1 part sodium iodide to every 100,000 parts sodium chloride.

The hormones produced by the thyroid gland are:

• Thyroxine and triidothyronine: increase the rate of chemical reactions in almost all cells of the body, thus increasing the general level of body metabolism.

• Calcitonin – promotes the deposition of calcium in the bones and thereby decreases calcium concentration in the extra cellular fluid.

About 93 percent of the metabolically active hormones secreted by the thyroid gland are thyroxine (T4) and 7 percent is triidothyronine (T3). However the hormone with the most biological activity is T3. Once released from the thyroid gland into the blood, a large amount of T4 is converted into T3 – the active hormone that affects the metabolism of cells. The functions of these two hormones are qualitatively the same, but they differ in rapidity and intensity of action. Triiodothyronine is about four times as potent as thyroxine, but it is present in the blood in much smaller quantities and persists for a much shorter time than does thyroxine.

Thyroid hormone secretion

The hypothalamus release a hormone called thyrotropin releasing hormone (TRH), which sends a signal to the pituitary to release TSH (Thyroid stimulating hormone). And then TSH sends signal to the thyroid to release thyroid hormones. If disturbance occurs at any of these levels, a defect in thyroid hormone production may result in a deficiency of thyroid hormone – resulting in hypothyroidism.

Causes of hypothyroidism

The common causes of hypothyroidism are:

• Hashimoto’s thyroiditis ( an auto immune disease of the thyroid gland – the immune system attacks and damages the thyroid tissue)

• Lymphocytic thyroidits, another type of inflammation of the thyroid, caused by white blood cells called lymphocytes. This condition is common after pregnancy. The initial phase of lymphocytic thyroiditis is normally caused by an excessive amount of thyroid hormone leaking from an inflamed thyroid gland, followed by a hypothyroid state that can last up to six months. Even if most women come back to a normal state of thyroid functioning, some may remain hypothyroid.

• Severe iodine deficiency

• Medical treatment – like radiation and surgery to the thyroid gland to treat hyperthyroidism (over – activity of the thyroid gland) – causing thyroid destruction.

• Pituitary or hypothalamic disease (if the defect is caused by pituitary disease, the condition is called secondary hypothyroidism. If the defect is due to hypothalamus disease, it is known as tertiary hypothyroidism).

• Certain drugs like lithium and phenylbutazone also induces hypothyroidism. Also drugs that are used to treat overactive thyroid like methimazole, propylthiouracil (PTU) can cause hypothyroidism.

• Psychiatric drugs (like lithium) and drugs containing large amounts of iodine may also cause hypothyroidism by decreasing levels of thyroid hormones in the blood. High iodine (drugs) intake like amiodarone, potassium iodide etc can initiate and worsen infiltration of the thyroid by lymphocytes. Lymphocytes are white blood cells that accumulate due to chronic injury or irritation. In addition, large amounts of iodine block the thyroid’s ability to make hormone.

Characteristics of hypothyroidism

The symptoms of hypothyroidism include fatigue and extreme somnolence with sleeping up to 12 to 14 hours a day, extreme muscular sluggishness, slowed heart rate, decreased cardiac output, decreased blood volume, sometimes increased weight, constipation, mental sluggishness, thin brittle nails, dry flaky and thickening skin, abnormal or heavy menstrual flow, hoarseness of voice, short stature, intolerance to cold, delayed formation or absence of teeth, failure of many tropic functions in the body evidenced by depressed growth of hair and scaliness of the skin, development of a frog – like husky voice and in severe cases, development of an edematous appearance throughout the body called myxedema.

Hashimoto’s thyroiditis

In this condition the thyroid gland is generally enlarged (goiter) and has a decreased ability to secrete thyroid hormones. It is an auto immune disease where the immune system attacks and damages the thyroid tissue. It can also be hereditary. This disease is more common in women than in men and can be most prevalent between 45 and 65 years of age.

Antibodies against thyroid peroxidase or thyroid globulin cause gradual destruction of follicles in the thyroid gland. Blood samples collected from the patients show an increased number of antibodies to the enzyme thyroid peroxidase (anti- TPO antibodies).

Symptoms in this disease first show the symptoms of hyperthyroidism in the early phase of disease and then hypothyroidism. Weight gain, depression, bradychardia, tachycardia, constipation, migraine, memory loss, infertility and hair loss are a few possible symptoms.

Hashimoto’s thyroiditis can be diagnosed by detecting anti-TPO antibodies in the blood or by performing a thyroid scan. Testing for anti-thyroid antibodies can resolve diagnostic difficulty. A radioactive uptake scan, which would show diffuse uptake in an enlarged thyroid gland.

Ultrasound - would show an enlarged thyroid gland.

Cretinism

Cretinism is caused by extreme hypothyroidism during fetal life, infancy and childhood.

This condition is characterized especially by failure of growth and by mental retardation.

It results from congenital lack of a thyroid gland (congenital cretinism), from failure of the thyroid gland to produce thyroid hormone because of a genetic defect of the gland or from iodine lack in the diet (endemic cretinism). The severity of endemic cretinism varies greatly, depending on the amount of iodine in the diet, and whole populaces of an endemic area have been known to have cretinoid tendencies.

A neonate without a thyroid gland may have normal appearance and function because it had been supplied with some thyroid hormone by the Mother while in utero, but a few weeks after birth, its movements become sluggish and both its physical and mental growth are greatly retarded. Treatment of cretin at any time usually causes normal return of physical growth but unless the cretin is treated within a few weeks after birth, its mental growth is permanently retarded. This results from retardation of the growth, branching and myelination of the neuronal cells of the central nervous system at this critical time in the normal development of the mental powers.

Skeletal growth in the cretin is characteristically more inhibited than is of soft tissue growth. As a result of this disproportionate rate of growth, the soft tissues are likely to enlarge excessively, giving the cretin the appearance of an obese and stocky short child.

Occasionally the tongue becomes so large in relation to the skeletal growth that it obstructs swallowing and breathing, inducing a characteristic guttural breathing that sometimes chokes the baby.

Myxedema

Myxedema develops in the patient with almost total lack of thyroid function. There is bagginess under the eyes and swelling of the face. In this condition, for reasons not explained, greatly increased quantities of hyaluronic acid and chondroitin sulfate bound with protein form excessive tissue gel in the interstitial spaces and this causes the total quantity of interstitial fluid to increase. Because of the gel nature of the excess fluid, it is relatively immobile and the edema is non-pitting in type.

Arteriosclerosis in hypothyroidism

Lack of thyroid hormone increases the quantity of blood cholesterol because of diminished liver excretion of cholesterol in the bile. The increase in blood cholesterol is usually associated with increased atherosclerosis and arteriosclerosis. Therefore, in many hypothyroid patients, particularly those with myxedema, arteriosclerosis develops, which results in peripheral vascular disease, deafness and often extreme coronary sclerosis with consequent early death.

Dietary changes

There are certain types of foods that are considered to be goitrogens (naturally occurring food substances that can interfere with the function of the thyroid gland). i.e. it refers the one that cause difficulty for the thyroid to produce its hormone.

The varieties of food that are considered to possess such properties are soy bean related foods, peanuts, radishes, spinach and cruciferous vegetables like broccoli, cabbage, cauliflower, mustard, turnip etc.

While some practitioners suggest that people with hypothyroidism avoid these foods, none has been confirmed to cause hypothyroidism in humans.

Lifestyle changes

Occupational hazards involving exposure to lead, brass industries, polybrominated biphenyls etc are found to suffer from symptoms of hypothyroidism.

Diagnostic test in hypothyroidism

The free thyroxine in the blood is low. The basal metabolic rate in myxedema ranges between 30 and 50. And the secretion of TSH by the anterior pituitary when a test dose of TRH is administered is usually greatly increased. (Except in those rare instances of hypothyroidism caused by depressed response of pituitary gland to the TRH).

Treatment of hypothyroidism

It is easy to maintain a steady level of thyroid hormone activity in the body by daily oral ingestion of a tablet or more containing thyroxine.

The chosen treatment is the intake of synthetic thyroid hormone – levothyroxine. (Synthroid – basically a T4 hormone). Some also prescribe desiccated thyroid known as Armour thyroid.

Furthermore, proper treatment of the hypothyroid patients results in such complete normality that formerly myxedematous patients have lived into their 90s after treatment for more than 50 years.

The Ayurvedic Medicines useful in treating Thyroiditis are Kaanchnaar guggulu, Chanderprabha vati, Maha yogaraja guggulu, Punarnava, Gokshura etc.

Herbal Pack for thyroiditis

• Kaanchnaar guggulu – 2 tablets twice daily

• Chanderprabha vati – 2 tablets twice daily

• Maha yogaraja guggulu – 2 tablets twice daily