Key difference: Hypothyroidism is a condition which arises from insufficient production of thyroid hormones by the thyroid gland. Cretinism is a condition arising from the deficiency of thyroid hormone, which causes dwarfism and mental retardation. It is present from birth.

Hypothyroidism is a condition which arises from insufficient production of thyroid hormones by the thyroid gland. It is a state in which the thyroid gland does not produce enough of the thyroid hormones, Thyroxine (T4) and Tri-iodothyronine (T3).

According to Wikipedia, iodine deficiency is often considered as the most common cause of hypothyroidism, but it can also be caused by many other factors. It can result from the lack of a thyroid gland or from iodine-131 treatment. It can also be related to increased stress. Severe hypothyroidism in infants can result in cretinism. Hypothyroidism can be classified on the basis of the infected organ dysfunction. They are as follows:

• Primary Hypothyroidism – It originates at the thyroid gland. The most common forms include Hashimoto's thyroiditis and radioiodine therapy for hyperthyroidism.
• Secondary Hypothyroidism – It originates at the pituitary gland. There is no clear cause for secondary hypothyroidism, as it is considered to be caused due to the damage to the pituitary gland by a tumor, radiation, or surgery. Secondary hypothyroidism accounts for less than 5% or 10% of hypothyroidism cases.
• Tertiary Hypothyroidism – It originates at the hypothalamus. It results when the hypothalamus fails to produce sufficient thyrotropin releasing hormone (TRH). TRH prompts the pituitary gland to produce thyroid-stimulating hormone (TSH).

The common cause of hypothyroidism is iodine deficiency. It can also be caused by lithium-based mood stabilizers, a medication usually used to treat bipolar disorder. Other drugs that may cause hypothyroidism include amiodarone, interferon alpha, interleukin-2 and thalidomide. Also, exposure to radioactive iodine-131 can stimulate a state of hypothyroidism and this method is used to medically treat hyperthyroidism. Stress is also a significant contributor to thyroid dysfunction. It can be environmental stress as well as homeostatic stress such as fluctuating blood sugar levels and immune problems. The stress effect can be direct or indirect. During pregnancy, there is a substantial increase in the need of thyroid hormones by the body and a substantial risk of hypothyroidism. Even mild or subclinical attack hypothyroidism is considered to adversely affect fertility.

Hypothyroidism can be easily diagnosed on the basis of TSH levels alone. However, this test is criticized by the doctors due to its inaccuracy to confirm the disease and that the thyroid hormone trial therapy is the best method for achieving diagnostic certainty. Another method to diagnose primary hypothyroidism is to measure thyroid-stimulating hormone (TSH) and free thyroxine (T4). These levels can be affected by other diseases. High levels of TSH indicate that the thyroid is not producing sufficient levels of thyroid hormones. Thus, the following blood tests are suggested:

• Free triiodothyronine (fT3)
• Free thyroxine (fT4)
• Total T3
• Total T4

Early hypothyroidism is often asymptomatic and can have very mild symptoms. It can be associated with a number of symptoms. These symptoms are also considered to relate to the underlying pathological cause of hypothyroidism, a mass effect of thyroid goitre, or direct effects of having insufficient thyroid hormones. Some earlier symptoms include thin and brittle fingernails, dry and itchy skin, weight gain, water retention and hair loss. People suffering from this disease undergo depression and have a rapid progression of thoughts. Women undergo infertility and menstrual irregularities. The symptoms after the disease include dry, puffy skin and the thinning of the outer third of the eyebrow. People have slow speech and hoarse voices. They are also affected by the carpal tunnel syndrome, which causes pain and numbness in the upper limb of the body. They undergo hypotension and have low basal body temperature. There are also a few uncommon symptoms which can be characterized by appearance: yellow skin, puffy face, hands and feet, enlarged tongue. The people suffer from impaired memory loss. They lose the sense of taste and smell. They have difficulty swallowing and experience shortness of breath with a shallow and slow respiratory pattern.

Hypothyroidism is treated with the regular and rotating doses of thyroxine (L-T4) and triiodothyronine (L-T3). Synthroid is a pill used to counteract to generic Levothyroxine. It is the most common pill prescribed by doctors. It has the synthetic thyroid hormone in it and it is taken by over 40% of people with hypothyroidism. This medicine helps improve symptoms of thyroid deficiency such as slow speech, lack of energy, weight gain, hair loss, dry skin and cold feeling. It also helps to treat goiter. It is also used to treat thyroid cancer along with surgery and other medicines. Both synthetic and animal-derived thyroid tablets are available and can be prescribed for patients in need of additional thyroid hormone. Thyroid hormone is taken daily, and doctors can monitor blood levels to help assure proper dosing. There is also the option of taking T4 individually, as it is the standard form; or taking T4 and T3 in combination.

Cretinism is a condition arising from the deficiency of thyroid hormone, which causes dwarfism and mental retardation. It is present from birth.

Congenital hypothyroidism is considered to be common, genetic or periodic. If left untreated, it can result into mild to severe impairment of physical and mental growth and development. Pause in the growth of height is apparent in the first year of life. Adult stature ranges from 1 to 1.6 meters without treatment, depending on the severity of the disease, sex and other genetic factors. In adults, cretinism results in mental deterioration, swelling of the skin, loss of water and hair. Bone maturation and puberty are severely delayed. In women, ovulation is impeded and infertility is common. Neurological impairment may be mild with reduced muscle tone and coordination. It can be so severe that the person cannot stand or walk. Cognitive impairment may also range from mild to so severe that the person becomes nonverbal and is dependent on others for basic care. Their thoughts and reflexes become slower. Other signs may include thickened skin, enlarged tongue, or a protruding abdomen. Periodic and genetic cretinisms result from abnormal development or the function of the foetal thyroid gland.

Cretinism arises due to deficiency of iodine in the diet. It has affected many people worldwide and continues to be a major public health problem in many countries. Iodine is an essential element, necessary and primary for the synthesis of thyroid hormones. Iodine deficiency is the most common preventable cause of brain damage. Although iodine is found in many foods, it is not universally adequately present in all soils. It also causes gradual enlargement of the thyroid gland, referred to as goiter.

The early 20th century saw the discovery of the relationships of periodic cretinism with hereditary hypothyroidism and of common cretinism with hypothyroidism due to iodine deficiency. It was combated in many countries by public health campaigns of iodine administration. It resulted in the elimination of the disease in many countries of the developed world.

Comparison between Cretinism and Hypothyroidism:

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