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The thyroid is a small, butterfly-shaped gland at the front of the neck that makes hormones controlling how the body uses energy. Those hormones affect nearly every organ: heart rate, body temperature, weight, mood, bowel habits, skin and hair, menstrual cycles and fertility. When the thyroid makes too little or too much hormone, or develops lumps, the effects can be felt throughout the body.
Thyroid disease is common and more frequent in women, but men develop it too. At NYMD Center our internal medicine physicians diagnose and manage the most common thyroid conditions: an underactive thyroid (hypothyroidism), an overactive thyroid (hyperthyroidism), thyroid inflammation (thyroiditis) and thyroid nodules. We coordinate with endocrinology when specialized treatment is needed.
Because thyroid symptoms overlap with so many other conditions, such as fatigue, weight change, anxiety or a racing heart, diagnosis depends on blood tests rather than symptoms alone. The tests are simple, and most thyroid conditions are very treatable once identified.
Types of thyroid disease and their symptoms
Hypothyroidism
An underactive thyroid slows the body down. The NIDDK lists fatigue, weight gain, feeling cold, joint and muscle pain, dry skin and hair, irregular or heavy periods, a slow heart rate and depression among the common symptoms. They tend to come on gradually over months or years, so people often attribute them to age or stress. The most common cause is Hashimoto's disease, an autoimmune condition in which the immune system attacks the thyroid. Thyroiditis, prior thyroid surgery or radiation, and some medications can also cause it.
Hyperthyroidism
An overactive thyroid speeds the body up: weight loss despite a good appetite, a rapid or irregular heartbeat, nervousness, tremor, heat intolerance, sweating, more frequent bowel movements and muscle weakness. Older adults may have subtler symptoms such as low appetite or withdrawal. According to the NIDDK, the most common cause is Graves' disease, an autoimmune condition; overactive nodules, thyroiditis, too much iodine and too high a dose of thyroid medication are others. Untreated hyperthyroidism can trigger atrial fibrillation and weaken bones, so it should not be ignored. If your heartbeat has become irregular, see our page on changes in heart rhythm.
Thyroid nodules and goiter
Nodules are lumps within the thyroid. Most are benign and cause no symptoms, and many are found by chance on imaging done for another reason. A few produce excess hormone, and a small share are cancerous. Large nodules or an enlarged thyroid (goiter) can cause a visible swelling or, less often, trouble swallowing or breathing.
How we evaluate thyroid disease at NYMD Center
The first test is TSH, the pituitary hormone that tells the thyroid how hard to work. A high TSH usually means an underactive thyroid and a low TSH an overactive one. If TSH is abnormal, we measure free T4, and T3 when an overactive thyroid is suspected. Thyroid antibody tests help identify Hashimoto's or Graves' disease. Because thyroid problems affect cholesterol and heart rhythm, we may also check a lipid panel and an ECG.
If you have a nodule, a swelling in the neck or an abnormal exam, we perform a thyroid ultrasound with our on-site ultrasound. Ultrasound shows a nodule's size and features and whether it looks reassuring or suspicious. When a nodule meets size and appearance criteria for biopsy, we refer you for an ultrasound-guided fine-needle aspiration, in which a thin needle draws cells for examination. As Cleveland Clinic explains, results may show normal cells, cancer or something in between that needs further testing. Many benign nodules are simply watched with repeat ultrasound.
Treatment options
Levothyroxine for an underactive thyroid
Hypothyroidism is treated with levothyroxine, a daily pill identical to the hormone a healthy thyroid makes. It is taken on an empty stomach, apart from calcium, iron and some other supplements that block absorption. The NIDDK notes that blood tests are usually repeated six to eight weeks after starting, then every six months to a year once the dose is stable. Most people need treatment for life, and the dose may need adjusting with weight change, aging or pregnancy. Mild TSH elevations without symptoms do not always need treatment; we discuss the trade-offs with you.
Treatment for an overactive thyroid
There are three main options, and the choice depends on the cause, your age and your preferences. Antithyroid medicines, usually methimazole, reduce hormone production; they take weeks to work and require blood monitoring. Radioactive iodine, taken as a pill, gradually destroys overactive thyroid tissue and often leaves the thyroid underactive, requiring levothyroxine afterward; it cannot be used in pregnancy or while breastfeeding. Surgery removes part or all of the gland. A beta blocker is often used early to control a racing heart and tremor. We begin evaluation and treatment in the office and refer to endocrinology and surgery as appropriate.
Nodules
Benign nodules are usually monitored. Overactive nodules are treated like hyperthyroidism, and suspicious or cancerous nodules are referred for surgery.
Thyroid disease, periods and pregnancy
Thyroid problems can cause irregular menstrual cycles and make it harder to become pregnant, and a TSH is part of any evaluation of either. During pregnancy the body's thyroid hormone needs rise, and untreated hypothyroidism can affect both mother and baby. Levothyroxine is safe in pregnancy, but the dose often needs to increase, so women on thyroid medication should let us know as soon as they are pregnant or planning to be. Hyperthyroidism in pregnancy is managed jointly with obstetrics and endocrinology.
What to expect at your visit
Bring your medication and supplement list, prior thyroid results and any imaging reports. Expect a review of symptoms, an examination of your neck, and blood work; if you have a nodule, an ultrasound may be done on site. An underactive thyroid also tends to raise cholesterol, which we recheck once thyroid levels are corrected, as covered on our hyperlipidemia page. Seek urgent care for a racing heart with chest pain, fainting or shortness of breath, high fever with confusion in someone with known hyperthyroidism, or sudden difficulty breathing or swallowing.
Questions patients ask
What blood test checks the thyroid?
The first test is TSH, thyroid-stimulating hormone, which rises when the thyroid is underactive and falls when it is overactive. If TSH is abnormal, we add free T4, and sometimes T3. Thyroid antibody tests help identify autoimmune causes such as Hashimoto's disease and Graves' disease. No fasting is required for these tests.
Is a thyroid nodule cancer?
Usually not. Most thyroid nodules are benign. An ultrasound shows the size and features of a nodule, and those features determine whether a fine-needle biopsy is needed. We perform thyroid ultrasound on site and refer for biopsy when a nodule meets the criteria. Many benign nodules are simply monitored with repeat ultrasound over time.
How long does it take for levothyroxine to work?
Many people start to feel better within a few weeks, but it takes several weeks for blood levels to settle. We usually recheck TSH six to eight weeks after starting or changing the dose, and adjust from there. Once the dose is stable, testing every six to twelve months is typical.
Can thyroid problems cause weight gain or weight loss?
Yes. An underactive thyroid can cause modest weight gain along with fatigue and feeling cold, while an overactive thyroid often causes weight loss despite a good appetite. Treating the thyroid condition usually helps, although thyroid disease rarely explains large weight changes on its own, so we look at other causes as well.
Should I have my thyroid checked if I am pregnant or trying to conceive?
If you have symptoms, a personal or family history of thyroid disease, or irregular periods, yes. Thyroid hormone needs rise in pregnancy, and untreated hypothyroidism can affect both mother and baby. Women already on levothyroxine often need a higher dose in pregnancy and should contact us as soon as they know they are pregnant.