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HYPOTHYROIDISM
What is hypothyroidism?
Whenever the thyroid gland is not producing enough thyroid hormones (T3 & T4) - it is referred as hypothyroidism.
These hormones have a widespread action on your metabolism, from the rate at which your heart beats to how quickly you burn calories, your growth, development and many other cellular processes.
The hormones secreted by the thyroid are thyroxine (T4) and triiodothyronine (T3). They maintain the rate at which your body uses fats and carbohydrates, help control your body temperature, influence your heart rate and even help regulate the production of protein. The secretion of T3 and T4 is controlled by the pituitary gland and the hypothalamus, which is part of the brain. Thyroid disorders may result not only from defects in the thyroid gland itself, but also from abnormalities of the pituitary or hypothalamus. The thyroid gland uses iodine (mostly available from the diet in foods such as seafood, bread, and salt) to produce thyroid hormones. The two most important thyroid hormones are thyroxin (T4) and free triiodothyronine (FT3), which account for 99.9% and 0.1% of thyroid hormones present in the blood respectively. 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. FT3 primarily exerts the metabolic action on the body. Hypothyroidism, or under activity of the thyroid gland, may cause a variety of symptoms and may affect all body functions. The body's normal rate of functioning slows, causing mental and physical sluggishness. The symptoms may vary from mild to severe, with the most severe form called myxedema, which is a medical emergency. Hypothyroidism is more common than you would believe...and, millions of people are currently hypothyroid and don't know it.
Your thyroid gland also produces calcitonin, a hormone that regulates the amount of calcium in your blood.
Causes
The most common cause of hypothyroidism is Hashimoto's thyroiditis, a disease of the thyroid gland where the body's immune system attacks the gland.
Pituitary failure :- Reduction or loss of TSH secretion by the pituitary is a rare cause of hypothyroidism. This constellation is usually referred to as "secondary hypothyroidism". Even rarer is tertiary hypothyroidism that is caused either by hypothalamic lesions or by interruption of signal transfer in the portal veins connecting the hypothalamus to the pituitary gland ( Pickardt syndrome).
Iodine deficiency :-Severe iodine deficiency is another major cause of hypothyroidism. In areas of the world where there is an iodine deficiency in the diet, severe hypothyroidism can be seen in 5 to 15% of the population. In many countries, iodine deficiency is very rare due to the small amount of iodine salt that is added to common table salt.
Other causes include congenital defects, surgical removal of the thyroid gland, irradiation of the gland, or inflammatory conditions.
Obesity, thyroid surgery, and exposure of the neck to X-ray or radiation treatments may be the causes.
The Early symptoms are:
 Weakness
Fatigue
Weight gain
Depression
Joint or muscle pain
Thin, brittle fingernails
Thin and brittle hair
Paleness
Muscle spasms (cramps)
If left untreated the symptoms may worsen and may be seen as:
Dry flaky skin
Slow speech
Thickening of the skin
Puffy face, hands and feet
Decreased taste and smell
Abnormal menstrual periods
Uncoordinated movement
Joint stiffness
Hair loss
Short stature
Separated sutures
Delayed formation or absence of teeth
Women are more likely than men to suffer from disorders of the thyroid.
Diagnostic Tests
Because hypothyroidism is more prevalent in older women, some endocrinologists recommend that women age 60 and older be screened for the disorder during routine annual physical examinations. Some doctors also recommend that pregnant women be tested for hypothyroidism.
In general, your doctor may test for an under active thyroid if you're feeling increasingly tired or sluggish, have dry skin, constipation and a hoarse voice, or have had previous thyroid problems or goiter.
A physical examination reveals delayed relaxation of muscles during tests of reflexes.
Mental slowing may be noted. Vital signs may reveal slow heart rate, low blood pressure, and low temperature. A chest X-ray may reveal an enlarged heart.
Laboratory tests to determine thyroid function include: T4, T3, FT3, FT4, AMA, ATG and serum TSH
Additional findings may reveal
Increased cholesterol levels
Increased liver enzymes
Increased serum prolactin
Low serum sodium
A complete blood count (CBC) that shows anemia
The severity of hypothyroidism varies widely. Patients are classified as "sub clinical hypothyroid" if diagnostic findings show thyroid hormone abnormalities, but they do not exhibit any symptoms. Others have moderate symptoms that can be mistaken for other diseases and states. Advanced hypothyroidism may cause severe complications, the most serious one of which is myxedema.
Left untreated, the symptoms of hypothyroidism will usually progress. Rarely, complications can result in severe life-threatening depression, heart failure or Myxedema coma.
Myxedema coma, the most severe form of hypothyroidism, is rare. It may be caused by an infection, illness, exposure to cold, or certain medications in an individual with untreated hypothyroidism. Symptoms and signs of myxedema coma include unresponsiveness, decreased breathing, low blood pressure, low blood sugar, and below normal temperature.
Other complications are heart disease, increased risk of infection, infertility, and miscarriage.
Prevention
There is no prevention for hypothyroidism; however, screening tests in newborns can detect congenital hypothyroidism.
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What is Hypothyroidism?