Ruchi Mathur, MD, FRCP(C) is an Attending Physician with the Division of Endocrinology, Diabetes and Metabolism and Associate Director of Clinical Research, Recruitment and Phenotyping with the Center for Androgen Related Disorders, Department of Obstetrics and Gynecology at Cedars-Sinai Medical Center.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
Hypothyroidism is a very common condition. It is
estimated that 3% to 5% of the population has some form of hypothyroidism. The
condition is more common in women than in men, and its incidence increases with age.
Below is a list of some of the common causes of hypothyroidism in adults followed by a
discussion of these conditions.
Hashimoto's thyroiditis
Lymphocytic thyroiditis
(which may occur after hyperthyroidism)
Thyroid destruction (from radioactive iodine or surgery)
Pituitary or hypothalamic disease
Medications
Severe iodine deficiency
Hashimoto's Thyroiditis
The most common cause of hypothyroidism in the United States
is an inherited condition called Hashimoto's thyroiditis. This condition is named after Dr. Hakaru Hashimoto who first described it in 1912. In this condition, the thyroid gland is
usually enlarged (goiter) and has a decreased ability to make thyroid hormones. Hashimoto's
is an autoimmune disease in which the body's immune system inappropriately attacks the thyroid
tissue. In part, this condition is believed to have a genetic basis. This means that the
tendency toward developing Hashimoto's thyroiditis can run in families. Hashimoto's is 5 to 10
times more common in women than in men. Blood samples drawn from patients with this disease
reveal an increased number of antibodies to the enzyme, thyroid peroxidase (anti-TPO antibodies).
Since the basis for autoimmune diseases may have a common origin, it is not unusual to find that
a patient with Hashimoto's thyroiditis has one or more other autoimmune diseases such as
diabetes or pernicious anemia ( B12 deficiency). Hashimoto's can be identified by detecting
anti-TPO antibodies in the blood and/or by performing a thyroid scan.
Lymphocytic thyroiditis following hyperthyroidism
Thyroiditis refers to inflammation of the thyroid gland. When the inflammation is caused by a
particular type of white blood cell known as a lymphocyte, the condition is referred to as
lymphocytic thyroiditis. This condition is particularly common after pregnancy and can actually
affect up to 8% of women after they deliver. In these cases, there is usually a
hyperthyroid
phase (in which excessive amounts of thyroid hormone leak out of the inflamed gland), which is
followed by a hypothyroid phase that can last for up to six months. The majority of affected women
eventually return to a state of normal thyroid function, although there is a possibility of
remaining hypothyroid.
Thyroid destructionsecondary to radioactive iodine or surgery
Patients who have been treated for a hyperthyroid condition (such as Graves' disease) and
received radioactive iodine may be left with little or no functioning thyroid tissue after
treatment. The likelihood of this depends on a number of factors including the dose of iodine
given, along with the size and the activity of the thyroid gland. If there is no significant
activity of the thyroid gland six months after the radioactive iodine treatment, it is usually
assumed that the thyroid will no longer function adequately. The result is hypothyroidism.
Similarly, removal of the thyroid gland during surgery will be followed by hypothyroidism.
Pituitary or Hypothalamic disease
If for some reason the
pituitary gland or the hypothalamus are unable to signal the thyroid and instruct it to produce
thyroid hormones, a decreased level of circulating T4 and T3 may result, even if the thyroid
gland itself is normal. If this defect is caused by pituitary disease, the condition is called
"secondary hypothyroidism." If the defect is due to hypothalamic disease, it is called
"tertiary hypothyroidism."
Pituitary injury
A pituitary injury may result after brain surgery or
if there has been a decrease of blood supply to the area. In these cases of pituitary injury,
the TSH that is produced by the pituitary gland is deficient and blood levels of TSH are low.
Hypothyroidism results because the thyroid gland is no longer stimulated by the pituitary TSH.
This form of hypothyroidism can, therefore, be distinguished from hypothyroidism that is
caused by thyroid gland disease, in which the TSH level becomes elevated as the pituitary gland
attempts to encourage thyroid hormone production by stimulating the thyroid gland with more TSH.
Usually, hypothyroidism from pituitary gland injury occurs in conjunction with other hormone
deficiencies, since the pituitary regulates other processes such as growth, reproduction, and
adrenal function.
Medications
Medications that are used to treat an over-active thyroid
(hyperthyroidism) may actually cause hypothyroidism. These drugs include methimazole (Tapazole)
and propylthiouracil (PTU). The psychiatric medication, lithium
(Eskalith, Lithobid), is also known to alter thyroid
function and cause hypothyroidism. Interestingly, drugs containing a large amount of iodine such
as amiodarone (Cordarone),
potassium iodide (SSKI,
Pima), and Lugol's solution can cause
changes in thyroid function, which may result in low blood levels of thyroid hormone.
Severe iodine deficiency:
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. Examples of these areas
include Zaire, Ecuador, India, and Chile. Severe iodine deficiency is also seen in remote
mountain areas such as the Andes and the Himalayas. Since the addition of iodine to table salt
and to bread, iodine deficiency is rarely seen in the United States.
Dizziness is a symptom that is often applies to a variety of sensations including lightheadedness and vertigo. Causes of dizziness include low blood pressure, heart problems, anemia, dehydration, and more. Treatment of dizziness depends on the cause.
Hyperthyroidism is an excess of thyroid hormone resulting from an overactive thyroid gland. Symptoms can include increased heart rate, weight
loss, depression, and cognitive slowing. Treatment is by medication, the use of
radioactive iodine, thyroid surgery, or reducing the dose of thyroid hormone.
There are four major types of thyroid cancer: papillary, follicular, medullary, and anaplastic thyroid cancer. Tumors on the thyroid are referred to as thyroid nodules. Symptoms of thyroid cancer include swollen lymph nodes, pain in the throat, difficulty swallowing, hoarseness, and a lump near the Adam's apple. Treatment usually involves chemotherapy, surgery, radioactive iodine, hormone treatment or external radiation and depends upon the type of thyroid cancer, the patient's age, the tumor size, and whether the cancer has metastasized.
Stress occurs when forces from the outside world impinge on the individual. Stress is a normal part of life. However, over-stress, can be harmful. There is now speculation, as well as some evidence, that points to the abnormal stress responses as being involved in causing various diseases or conditions.
Raynaud's phenomenon is characterized by a pale-blue-red sequence of color changes of the digits, most commonly after exposure to cold. Occurring as a result of spasm of blood vessels, the cause is unknown. Symptoms of Raynaud's phenomenon depend on the severity, frequency, and duration of the blood vessel spasm. Treatments include protection of the digits, medications, and avoiding emotional stresses, smoking, cold temperature, and tools that vibrate the hands.
Restless leg syndrome (RLS or restless legs syndrome) is a common cause for painful legs that typically eases with motion, and becomes worse and more noticeable at rest. This characteristic nighttime worsening can frequently lead to insomnia. Treatment of the symptoms of restless leg syndrome is generally with medication as well as treating any underlying condition causing restless leg syndrome.
Hashimoto's thyroiditis is the most common cause of hypothyroidism in the US. This conditions is caused by inflammation of the thyroid gland. Symptoms may include: fatigue, weight gain, cold intolerance, excessive sleepiness, dry or coarse hair, difficulty swallowing, a lump in the front of the throat, and many more. Treatment is usually hypothyroid medication.
Carpal tunnel syndrome is a condition in which irritation of the wrist's median nerve causes tingling and numbness of the thumb, index, and the middle fingers. This condition is known as tarsal tunnel syndrome in the ankles and feet. Treatment of carpal tunnel syndrome depends on the severity of the symptoms and the nature of any disease that might be causing the symptoms.
Thyroid nodules are the most common endocrine problem in the United States. The term "thyroid nodule" refers to any abnormal growth that forms a lump in the thyroid gland. The vast majority of thyroid nodules are benign.
Hyponatremia is a condition where the level of sodium in the blood is low. Causes of hyponatremia can occur from excess fluid in the body, or a loss of sodium in body fluid. Some of the symptoms of hyponatremia include headache, muscle cramps or spasm, seizures, weakness and confusion. Treatment of hyponatremia depends on the cause.
There are many types of thyroid disease. Some occur due to the function of the thyroid itself such as hypothyroidism, hyperthyroidism, Hashimoto's thyroiditis, etc. Some causes of thyroid disease occur due to problems with the structure of the thyroid gland such as goiters, thyroid nodules, and thyroid cancer. Treatment of thyroid disease depends on the cause of the disease.
Rhabdomyolysis is a rapid deterioration and destruction of skeletal muscle. Some of the causes of rhabdomyolysis include severe burns, muscle trauma, coma, seizures, electrolyte imbalance, medications (statins), viruses, bacteria. Treatment of rhabdomyolysis depends on the cause.
Obesity is the state of being well above one's normal weight. A person has traditionally been
considered to be obese if they are more than 20 percent over their ideal weight.
That ideal weight must take into account the person's height, age, sex, and
build.
Pleural effusion is an excess fluid between the two membranes that envelop the lungs. There are two classifications of causes of pleural effusion; transudate and exudate. The treatment of pleural effusion depends on the cause.
Hypothyroidism during pregnancy can be treated with synthetic thyroid hormones to maintain the proper thyroid hormone balance. Hypothyroidism symptoms include fatigue, weight gain, lethargy, and constipation. Treatment of hypothyroidism in pregnant women is important, because inadequate levels of thyroid hormones may affect the fetus, and child during growth and development.
Hypothermia is having a body core temperature of less than 35 C or 95 F. Most causes of hypothermia are preventable. Risk factors for hypothermia include age, mental status, medical conditions, and medications. Symptoms of hypothermia generally depend upon the severity of the condition. Treatment depends upon the severity of hypothermia. If not treated early, hypothermia can lead to cardiac arrest, coma, or death.
Amenorrhea is a condition in which there is an absense of menstrual periods in a woman. There are two types of amenorrhea, 1) primary and 2) secondary. Treatment of amenorrhea depends on the type (primary or secondary). In prmiray, surgery may be an option and in secondary amenorrhea medication or lifestyle changes may be treatment options.
Fatigue can be described in various ways. Sometimes fatigue is described as feeling a lack of energy and motivation (both mental and physical). The causes of fatigue are generally related to a variety of conditions or diseases for example, anemia, mono, medications, sleep problems, cancer, anxiety, heart disease, drug abuse, and more. Treatment of fatigue is generally directed toward the condition or disease that is causing the fatigue.
Dry skin (xeroderma) may be caused by external factors, like cold temperatures, low humidity, harsh soaps, and certain medications, or internal factors, such as thyroid disease, diabetes, psoriasis, or Sjogren's syndrome. Symptoms and signs of dry skin include itching and red, cracked or flaky skin. The main treatment for dry skin is frequent, daily lubrication of the skin.
Myxedema coma is the loss of brain function due to severe longstanding low levels of thyroid hormone in the blood. Myxedema coma is a life-threatening complication of hypothyroidism. Examples of triggers of myxedema coma include medications, infections stroke, trauma and more. Some of the ymptoms of myxedema coma include: hypothermia, seizures, coma, difficulty breathing and more. Treatment of myxedema coma depend on the severity of the condition.
Premature ovarian failure (POS) is the cessation of normal functioning of the ovaries in women under the age of 40. Premature ovarian failure may be caused by follicle depletion or dysfunction. The most common symptom of premature ovarian failure are irregular periods. There is no "treatment" that will restore the ovarian function, but there are treatments that my relieve symptoms.
Millions of women suffer from urinary incontinence (UI). UI occurs twice as often in women as in men. There are many types of urinary incontinence: stress incontinence, urge incontinence, overactive bladder, functional incontinence, overflow incontinence, transient incontinence, and mixed incontinence.
Thyroiditis is the inflammation of the thyroid gland. The inflamed thyroid gland can release an excess of thyroid hormones into the blood stream, resulting in a temporary hyperthyroid state. Some forms of thyroiditis can be diagnosed based on tenderness and enlargement of the thyroid gland. A thyroid scan sometimes is used in making the diagnosis. Thyroiditis can also be diagnosed with a biopsy of the thyroid gland.
Cholesterol occurs naturally in the body. High blood cholesterol levels increase a person's risk of developing heart disease, heart attacks, strokes, TIAs, and more. In addition to medication (fibrates, statins, bile acid sequestrants, and niacin), lifestyle changes can be made to lower blood cholesterol levels
Pendred syndrome, a genetic disorder that causes hearing loss. Generally, the hearing loss is affected in early childhood. Pendred syndrome also affects other parts fo the body (for example, the thyroid gland). Treatment is generally cochlear ear implants.
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