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Thyroid Guide


Hypothyroidism

Hypothyroidism

General Overview
The thyroid is a small butterfly-shaped gland that rests in the middle of the lower neck. Its primary function is to control the body's metabolism. To control metabolism, the thyroid produces hormones (thyroxine - T4 and triiodothyronine - T3), which tell the body's cells how much energy to use. A properly functioning thyroid will maintain the right amount of hormones needed to keep the body's metabolism functioning at a normal metabolic rate. The quantity of thyroid hormones in the bloodstream is monitored and controlled by the pituitary gland. This gland produces thyroid hormone, which helps to regulate growth and metabolism. The diseases of the thyroid are considered to be the second most common conditions worldwide next to diabetes. Hypothyroidism is a condition in which the thyroid gland does not produce sufficient quantity of hormone to meet the requirement of the body. Though it can affect people of all ages, women are more commonly affected by this condition than men.
The prevalence of thyroid disorders in India is estimated to be 42 millions, according to countrywide studies conducted in 2000. In a study conducted in Meghalaya, India, the prevalence of hypothyroidism was found to be 3.33% in non-pregnant women of age group 36 to 45 years and 3.70% in pregnant women in the age group 15 to 25 years. Another study conducted in Kolkata has shown higher prevalence of hypothyroidism in the age group of 36 to 45 years. Studies have also shown that prevalence of hypothyroidism is 5.4% among those who have goiter.
Introduction
What is hypothyroidism?
Hypothyroidism is a condition in which the thyroid gland is unable make adequate quantity of thyroid hormones (T4 and T3) needed for the normal functioning of the body. It is also known as underactive thyroid disease. It is the most common thyroid disorder. Lower level of thyroid hormones slows down your body's metabolism. This condition also affects your thyroid gland, the cells of which are destroyed slowly by your own immune system (body's defense system) causing your gland to shrink in size. Though the condition is progressive and irreversible, it is often completely treatable, allowing you to lead a normal life. It occurs more commonly in women (especially those over 50 years of age) than men. Hypothyroidism usually causes you to suffer from joint pains, obesity, infertility, and heart diseases. Severe hypothyroidism can lead to myxedema, which is a rare and life-threatening condition characterized by thick, dry skin, swelling in your face and hands, and lack of emotions. Complications of hypothyroidism include heart disease, higher susceptibility to infection, miscarriage, and infertility.
Signs and Symptoms
What are the symptoms of hypothyroidism?
Your symptoms of hypothyroidism usually develop slowly. Symptoms can vary from person to person, and you may usually notice a constant feeling of tiredness and lack of energy. Other symptoms include:
  • heightened sensitivity to cold.
  • constipation.
  • dry hair and skin.
  • puffiness of face.
  • droopy eyelids.
  • thinning or falling out of eyebrows.
  • hoarseness of voice.
  • slow speech.
  • increased blood cholesterol.
  • increase in weight.
  • muscle pain, cramps, stiffness, or tenderness.
  • pain, swelling, or stiffness in your joints.
  • heavy menstrual periods.
  • depression.
  • forgetfulness.
  • co nfusion.
  • enlarged thyroid.
  • slow pulse.
  • carpal tunnel syndrome (tingling or pain caused by nerve compression at the wrist).
  • anemia.
  • orange-colored soles and palms.
Causes
What are the causes of hypothyroidism?
There are many reasons for you to develop hypothyroidism. The important causes are mentioned below.
Thyroiditis and autoimmune disorder:
Thyroiditis is the inflammation of thyroid gland, due to an autoimmune or viral cause. Autoimmune disorder is a condition, where your body tissues are attacked by your own immune system. Hashimoto's thyroiditis is a common autoimmune disease wherein the antibodies attack the thyroid gland resulting in reduced production of the hormones. Thyroiditis can sometimes develop during or after pregnancy.
Hyperthyroidism treatment:
Sometimes, treatment of hyperthyroidism (a condition in which thyroid gland produces too much of thyroid hormones) can cause destruction of a portion of thyroid gland resulting in insufficient production of hormones.
Congenital disease:
This is a condition in which you are born with a defective thyroid gland or with no thyroid gland at all.
Pituitary disorder:
Pituitary gland produces hormones that control other glands including the thyroid gland. Any damage to pituitary gland may affect the thyroid gland causing it to produce too little quantities of hormone.
Iodine deficiency:
Iodine is essential for the thyroid gland to produce its hormones. You can develop hypothyroidism, if there is a chronic lack of iodine in your diet.
Risk Factors
Find out if you are at risk of developing hypothyroidism
Although hypothyroidism can affect any person, certain factors could increase your risk. They include:
  • Family history. Having a parent or sibling with autoimmune thyroid disease can increase your risk.
  • Age. Though you may develop hypothyroidism at any age, your risk increases as you grow older.
  • Gender. Women are at a higher risk of developing hypothyroidism than men especially in their younger ages. As age progresses, the risk of both men and women developing hypothyroidism remains the same.
  • Ethnicity. Your risk can increase, if you are a White, Caucasian, or an Asian, while being an African American reduces your risk.
  • Medical conditions. You are at a higher risk of developing hypothyroidism, if you have already been diagnosed with other problems such as rheumatoid arthritis, multiple sclerosis, celiac disease, Addison's disease, pernicious anemia, vitiligo, Down's syndrome/Turner's syndrome, gout, breast cancer, myasthenia gravis, and polycystic ovarian syndrome.
  • Pregnancy. If you are a woman, your risk of developing hypothyroidism increases during and after pregnancy, as well as around menopause.
Diagnosis and Screening
How will my doctor diagnose hypothyroidism?
To evaluate whether you have hypothyroidism, your doctor will record a detailed medical and family history, and perform a physical examination.
Medical and family history:
Your doctor will question you about:
  • Any family history of thyroid disease.
  • The presence of any symptoms that you may be having or have experienced.
  • Any thyroid surgery or radiation treatment on your neck.
  • Medicines that you are currently taking or have taken earlier (such as those used to treat hyperthyroidism), as some medications could trigger hypothyroidism.
Physical examination:
Your doctor will conduct a thorough physical examination, during which he will:
  • Check your thyroid gland.
  • Look for the presence of any swelling in your face, arms, and legs.
  • Look for changes in your skin and hair, such as dryness, brittleness, and coarseness.
  • Check your pulse to calculate the rate at which your heart is beating.
  • Check your reflexes for any signs of reduction.
Do I need testing?
On initial evaluation, if your doctor suspects hypothyroidism, he will advise you to undergo certain diagnostic tests, such as blood tests to measure the hormone levels.
Blood tests:
Thyroxine (T4) test: T4 is a hormone produced by the thyroid gland, which is markedly reduced in hypothyroidism. During this test, your blood is collected from a vein, usually from bend in your elbow or the back of your hand. As some drugs can alter the results, your doctor may advise you to stop them before the test. Your normal T4 levels will range between 4.5 mcg/dL to 11.2 mcg/dL.
Triiodothyronine (T3) test: T3 is a hormone produced by the thyroid gland, which is markedly reduced in hypothyroidism. During this test, your blood is collected from a vein, usually from bend in your elbow or the back of your hand. As some drugs can alter the results, your doctor may advise you to stop them before the test. Your normal T3 levels will range between 100 ng/dL to 200 ng/dL.
Thyroid-stimulating hormone (TSH) test: TSH is a hormone produced by the pituitary gland, which regulates the production and release of the hormones T4 and T3 from the thyroid gland. This is the most important and sensitive test for diagnosing hypothyroidism. A marked increase in the level of TSH indicates that you have hypothyroidism. During this test, your blood is collected from a vein, usually from bend in your elbow or the back of your hand. As some drugs can alter the results, your doctor might advise you to stop them before the test. Your normal TSH levels will range between 0.4 mIU/L to 4.0 mIU/L.
Antithyroid antibodies: Your doctor may recommend this test to diagnose autoimmune thyroid disorder, when other thyroid test results (T4, T3, and/or TSH) show signs of thyroid dysfunction and/or for investigating the cause of goiter (enlarged thyroid gland). During this test, your blood is collected from a vein, usually from bend in your elbow or the back of your hand. There is no standard reference range for this test. Presence of thyroid antibodies indicates that you have an autoimmune thyroid disease. The higher the level of antibodies, the greater is your chance of having autoimmune thyroid disease. Increasing antibody levels rather than stable levels are more significant.
Other blood tests: You may also be advised to undergo other blood tests for calculating your levels of cholesterol, liver enzymes, and prolactin, as all these may be increased in hypothyroidism. You may also have to undertake tests for calculating your sodium levels that will be reduced, and a complete blood count for the presence of anemia, which is often associated with hypothyroidism.
Treatment
How is hypothyroidism treated?
The management of hypothyroidism will involve the replacement of the deficient levels of thyroid hormone. This hormone replacement therapy (replacing the amount of hormone that your thyroid gland is unable to produce) helps to normalize your hormone levels.
Your doctor will prescribe the lowest dose, which is effective in relieving all your symptoms. You will have to take the treatment for lifelong, and you will have to continue the medication even after the symptoms subside.
Levothyroxine:
This is a synthetic thyroxine pill, which contains the hormone similar to the natural thyroxine (T4) made by the thyroid gland. It is the most commonly used medication, which is taken once a day, preferably in the morning.
Self Care and Lifestyle Change
Hypothyroidism is a condition that cannot be cured, but can be completely controlled. Certain precautions and lifestyle changes mentioned below will help you to cope with hypothyroidism.
  • Regularly consult your doctor to monitor your thyroid hormone levels, so that he can adjust your medications, if needed.
  • Report your doctor, if you experience any symptoms such as restlessness, rapid weight loss, and sweating, after commencing your treatment. These could indicate increased thyroid activity.
  • Inform your doctor of any other drugs and/or supplements that you are taking or planning to take before or during treatment with thyroid hormones, as their effectiveness could reduce due to interactions with other drugs or food supplements.
  • Consult with a dietitian on intake of iodine, medications, vitamins, and mineral supplements.
  • Avoid eating foods high in goitrogens especially raw vegetables (cauliflower, sweet potatoes, cabbage, etc) and increase the intake of foods high in iodine in the diet.
References