Thyroid Disease

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The thyroid is an endocrine gland in the neck that regulates a variety of bodily processes related to energy consumption, protein synthesis, and hormone responsiveness. It participates in these pathways by producing hormones itself, specifically thyroxine (T4) triiodothyronine (T3), and calcitonin. The delicate balance of these hormones ultimately defines the speed and efficiency of many of our metabolic processes, influencing the way we feel physically, mentally, and emotionally.

Thyroid problems can sigificantly affect your life. If you feel that your thyroid is not functioning properly, please call our patient coordinator at 1-212-679-9667 or click on Appointment to schedule an appointment to see one of our doctors for evaluation and testing. The TRH Stimulation Test is a more sensitive thyroid test to detect a low thyroid that could have been missed by routine blood tests. This is a challenge test that evaluates how well the pituitary and thyroid gland is functioning properly. By using the TRH stimulation test we frequently pick up the low thyroid diagnoses missed by many doctors.

Structurally, the principal thyroid hormones T4 and T3 only differ only by one iodine atom. (T4 contains four, while T3 contains three.) T4 is actually considered a prohormone, a precursor to T3, which becomes approximately four times more active upon conversion. 90% of the thyroid hormone is released as T4, which can circulate and be converted to T3 as needed by the thyroid, liver, spleen, and kidneys. T3 activates the production of proteins involved in the breakdown of nutrients to produce energy and heat. Through these pathways, T3 and T4 regulate metabolism, body temperature, growth, and heart rate. The other thyroid hormone, calcitonin, contributes more specifically to the normalization of blood calcium levels.

Release of thyroid hormones T4 and T3 is controlled by the hypothalamus, the portion of the brain considered to be the “master regulator” of hunger, thirst, fatigue, circadian rhythms, and many other complex processes. If a shift in one of these physiological states is warranted, the hypothalamus releases thyrotropin-releasing hormone (TRH), which stimulates production of thyroid-stimulating hormone (TSH) from the pituitary gland. TSH can then communicate to the thyroid gland that more thyroid hormones should be secreted. Beyond this, T4 and T3 levels are balanced through a feedback loop with thyrotropes, the cells in the pituitary gland which release TSH. In other words, if T4/T3 levels are high, TSH production will be reduced so that additional thyroid hormones are not produced. If T4/T3 levels are low, TSH will stimulate the production of more of these hormones to maintain a balance.

Calcitonin is released by the thyroid in response to hypercalcemia, a state of high blood calcium. By facilitating the movement of calcium from the blood into the bones, calcitonin reduces blood calcium to more physiologically preferable levels. Should blood calcium become too low, levels are rebalanced by parathyroid hormone (PTH) released by the parathyroid glands. These smaller endocrine glands in the back of the neck are located behind the thyroid. Generally, PTH seems to have a greater impact on calcium metabolism, as parathyroid removal seems to have a more profound effect on blood calcium balance than thyroid removal.

Thyroid hormones are also affected by other hormones in the body, such as estrogen. Because estrogen levels reduce the efficiency of thyroid hormones, women tend to have higher levels of T3 and T4 than men. As a result, women tend to have larger thyroids and are more susceptible to thyroid diseases and imbalances than men.

Thyroid disease is quite prevalent, effecting as many as 20 million Americans, many of them undiagnosed. Because of the general nature of some of the symptoms, mild thyroid imbalances may be particularly difficult to identify. Unless a thyroid disorder is suspected, thyroid function tests are rarely given until the symptoms worsen or there becomes a pronounced change in the gland itself. Unfortunately, this leads many sufferers of thyroid problems to live with their symptoms far longer than necessary.

Thyroid Symptoms

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Are you experiencing any of these symptoms; • Fatigue and weakness • Low basal temperature ( cold intolerance) • Dry and coarse skin • Hair loss • Cold hands and feet • Weight gain • Insomnia • Constipation • Depression • Poor memory, forgetfulness, dementia • Nervousness and tremors • Immune system problems • Heavy menstrual periods? Then it is a good possibility that you have a low thyroid, or HYPO-THYROIDISM.

Hypothyroidism results from an underactive thyroid gland and frequently results in weight gain, through slowed metabolism and water retention. Low thyroid hormone levels may also result in thinning hair, brittle nails, pale skin, poor muscle tone, and low heart rate. Energy levels may be quite low, frequently leading to fatigue even in the absence of exertion. Muscle cramping, painful joints, and sensitivity to cold can also result from hypothyroidism. Thyroid hormone T3 also influences the levels of serotonin, a neurotransmitter that helps define mood. Thus, insufficient T3 can also lead to depression.

Are you experiencing any of these symptoms; • Fatigue and weakness • Heat intolerance • Dry and coarse skin, clammy skin • Hair loss • Warm hands and feet • Weight loss • Insomnia • Depression • Poor memory, forgetfulness • Nervousness and tremors • Immune system problems • Light menstrual periods • Frequent defecation? Then it is a good possibility that you have an overactive thyroid, or HYPER-THYROIDISM.

An overactive thyroid gland releases too many hormones, resulting in hyperthyroidism. Because thyroid hormones speed up the rate of metabolism, increasing energy consumption, people with hyperthyroidism often have increased appetite, but are prone to weight loss regardless of caloric intake. They may also feel hyperactive, intolerant to heat, short of breath, and experience heart palpitations. Extreme thirst, increased urination, nausea, vomiting, and diarrhea can also occur. As the body’s energy supplies are exhausted, sufferers of hyperthyroidism may feel fatigued, weak, depressed, and even delirious. The eyelids may also remain open slightly wider than normal, a symptom known as “Dalrymple’s sign.”

Other symptoms of thyroid that commonly accompanies hypothyroidism is goiter, a swelling of the thyroid gland due to excessive stimulation by thyroid-stimulating hormone (TSH). A normally functioning thyroid gland would respond to the TSH by producing thyroid hormones which would, in turn, stop the release of TSH. In the case of hypothyroidism, because thyroid hormone levels are never restored, TSH stimulation never ceases. As a result, the cells in the thyroid gland divide excessively, causing the whole gland to increase in size and bulge from the neck. The eyes may also begin to protrude.

There are also several types of thyroiditis, characterized by inflammation of the thyroid. The thyroid gland may become swollen, tender, and painful to touch, and the person may develop a fever. Sometimes, thyroiditis is also accompanied by symptoms of hyper- or hypothyroidism.

Thyroid cancer is often detected following the development of thyroid nodules on the gland. Statistically, thyroid nodules are quite common, found in 50% of the population according to some statistics. The vast majority of these lumps are benign and cause no symptoms at all. Still, a medical work-up is recommended to make sure they are not cancerous. Doctors may perform ultrasounds or biopsies to more closely examine the nodules, in case there is a problem.

Thyroid problems can sigificantly affect your life. If you feel that your thyroid is not functioning properly, please call our patient coordinator at 1-212-679-9667 or click on Appointment to schedule an appointment to see one of our doctors for evaluation and testing.

Causes of Thyroid Disease

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The most common cause of hyperthyroidism is Graves’ disease, an autoimmune disorder. In patients with this disease, the immune system develops antibodies to the thyrotropin receptors on the thyroid gland. Under normal conditions, these receptors bind thyroid-stimulating hormone (TSH) produced by the pituitary gland, which causes the thyroid to produce thyroid hormones. TSH is released in a controlled fashion from the pituitary gland, meaning controlled stimulation of thyroid hormone production. In Graves’ disease patients, the antibody binds and continuously stimulates the thyrotropin receptors, resulting in constant release of thyroid hormones. The cause of Graves’ disease is unknown, though it appears to have a strong hereditary component.

Historically, insufficient iodine intake was the primary cause of hypothyroidism, and it remains a common cause in developing countries. Iodine is a major component of thyroid hormones T3 and T4, so without it, these major thyroid hormones cannot be made. The most common cause of hypothyroidism in individuals that have adequate iodine levels is Hashimoto’s thyroiditis, an autoimmune disorder in which the body mounts an immune response to the cells of the thyroid gland. As its cells are destroyed, the thyroid becomes progressively less functional, causing T3 and T4 levels to drop far below normal. A few specific genes involved in the regulation and specificity of the immune response have been implicated in increasing the risk of Hashimoto’s thyroiditis.

Other types of thyroiditis contribute to thyroid hormone imbalances, as well. Viral infections can cause inflammation of the thyroid, leading to increased release of thyroid hormones. Approximately 5% of pregnant women develop postpartum thyroiditis, a condition thought to stem from changes in the immune system that occur to accommodate pregnancy. Postpartum thyroiditis may cause hyper- or hypothyroidism (or both) as the woman’s body rebalances itself. Most women return to normal thyroid output during the year following the pregnancy, however, some may retain the imbalance and require lifelong treatment for whichever condition remains.

Thyroid nodules can lead to either hyper- or hypothyroidism, depending on whether the thyroid cells within the lump are “hot” or “cold.” “Hot” nodules are composed of cells that release hormones in an uncontrolled way, no longer regulated properly by the normal signals. Conversely, “cold” nodules produce no hormones, thus contributing to hypothyroidism.

There are four different types of thyroid cancers that can potentially cause thyroid hormone imbalances and thyroid gland enlargement. The most common is papillary thyroid cancer, which accounts for approximate 75% of thyroid cancer cases. Papillary tumors are cystic masses that form from otherwise normal thyroid hormone producing tissue and tend to stay fairly localized. Follicular thyroid cancers, however, are more invasive and more likely to spread to other parts of the body. Medullary thyroid cancers occur in the parafollicular cells of the thyroid which produce the hormone calcitonin. Anaplastic thyroid cancers are the rarest form of thyroid cancer, but are the most invasive and have the poorest prognosis for patients.

Next Steps:

Thyroid problems can sigificantly affect your life. If you feel that your thyroid is not functioning properly, please call our patient coordinator at 1-212-679-9667 to schedule an appointment to see one of our doctors for evaluation and testing.

We are located at: Patients Medical PC, 800 Second Avenue, Suite 900 (Between 42nd & 43rd Street), Manhattan, NYC, New York, NY 10017.