Answering common questions about thyroid disease
2/12/2024 by Richard Lindsey, M.D., Ph.D.
Thyroid hormone is vital for a healthy metabolism and overall health. If the thyroid level is too low or too high, it can be harmful to both physical and mental health. The thyroid hormone is produced by the thyroid gland, a small gland in the middle of the lower neck.
Thyroid diseases affect roughly 5% to 10% of the U.S. population, and many are unaware of their condition. Women are more likely than men to have thyroid problems.
If you suspect you're having a problem with your thyroid, answers to these common questions may provide clarity.
What is thyroid disease?
There are multiple types of thyroid disease, and they can either cause the body to produce too little or too much thyroid hormone. When thyroid hormone levels are too low, patients can develop conditions such as heart failure, high cholesterol, depression or weight gain. When thyroid hormone levels are too high, patients can develop atrial fibrillation, anxiety or osteoporosis.
Nodules in the thyroid gland are also very common. They may or may not be associated with altered thyroid hormone levels. Most are benign and do not cause any problem, but if you find a lump in your neck it's best to speak with your primary care clinician to determine if further testing is needed.
What are the symptoms of thyroid disease?
Since thyroid hormone affects so many systems in the body, there are many symptoms which could be an indication of thyroid problems:
- People with hypothyroidism, or not enough thyroid hormone, commonly experience fatigue, intolerance to cold, weight gain, constipation, dry skin and irregular menstrual cycles.
- People with hyperthyroidism, or too much thyroid hormone, can experience anxiety, exaggerated emotions, weakness, tremors, heart palpitations, intolerance to heat, increased perspiration, irregular menstrual cycles and weight loss.
How are thyroid problems diagnosed?
Because symptoms of thyroid hormone imbalance are so common and are often caused by health conditions unrelated to thyroid disease, the first step is to evaluate the function of your thyroid using a test for thyroid stimulating hormone, or TSH. TSH is secreted by the pituitary gland in response to your body's levels of thyroid hormone. A normal TSH in adults is 0.3 to 4.2 milli-international units per liter. Levels can be higher as we age.
If there isn't enough active thyroid hormone, TSH levels will rise as the pituitary gland tries to stimulate the thyroid to make more. If there's too much thyroid hormone, TSH levels fail to stop stimulating production. People whose TSH is in the normal range are unlikely to have thyroid disease. If you're diagnosed with this condition, your clinician will request that your TSH be checked periodically to monitor your response to treatment.
It's also possible to have an abnormal TSH level but a normal thyroid hormone level. This is called "subclinical" hyperthyroidism or hypothyroidism. These conditions generally don't need to be treated. However, there are important exceptions that you should discuss with your healthcare clinician. All patients with subclinical thyroid disease should have their TSH and thyroid hormone levels checked regularly to detect if the condition has progressed or if there's a need for treatment.
How are thyroid problems treated?
Treatment for thyroid problems depends on whether your thyroid hormone levels are too high or too low.
- Hypothyroidism (hormone levels too low, TSH too high). This condition is more common and tends to affect women more than men. It can be caused by autoimmune thyroid diseases, such as Hashimoto's thyroiditis, radiation to the thyroid or pituitary gland, certain medications or other health conditions. It is treated with hormone replacement therapy (a medication called levothyroxine). Your dose will be adjusted based on regular TSH tests.
- Hyperthyroidism (hormone levels too high, TSH too low). This condition can be caused by autoimmune thyroid disease, such as Grave's disease, certain medications, hyperactive nodules, infection or injury to the thyroid gland. The most common cause is taking too much thyroid hormone for hypothyroidism. Treating hyperthyroidism is more challenging than hypothyroidism, and treatment depends on the cause of elevated thyroid hormone levels.
It's important for all patients taking levothyroxine to have their TSH monitored and doses adjusted to maintain TSH in the normal range.
Keep in mind that symptoms suggestive of thyroid problems are common and most often not caused by thyroid disease. It's important to discuss your symptoms and concerns with your healthcare clinician and be screened and treated for thyroid disease, if necessary.
Richard Lindsey, M.D., Ph.D., is a resident physician in the Department of Medicine Primary Care Clinic in Rochester, Minnesota. He earned his medical and doctoral degrees at Loma Linda University School of Medicine in Southern California. In July 2024, he will be an Endocrinology fellow at Mayo Clinic in Rochester. His interests include endocrine physiology, osteoporosis and mechanisms of bone metabolism and aging.