Hyperthyroidism, also known as overactive thyroid, is a condition in which the thyroid gland produces excess thyroid hormones. The main thyroid hormones are triiodothyronine (T3) and thyroxine (T4). An excess of these hormones causes the body’s metabolism to speed up. This can lead to a variety of symptoms including unexplained weight loss, rapid or irregular heartbeat, sweating, nervousness, irritability, tremors, insomnia, thinning hair, muscle weakness and many other signs and symptoms.
The hallmark or classic sign of hyperthyroidism is a low serum thyroid-stimulating hormone (TSH) level. TSH is produced by the pituitary gland in the brain and helps regulate thyroid hormone production. When TSH levels are low, it indicates that the thyroid is overproducing its own hormones independently of the pituitary gland. Measuring TSH levels through a simple blood test is the first step in diagnosing hyperthyroidism. If TSH is low, further evaluation will confirm abnormally high T4 and/or T3 levels.
What causes hyperthyroidism?
There are several potential causes of hyperthyroidism:
Graves’ disease
The most common cause of hyperthyroidism is Graves’ disease, an autoimmune disorder that causes the body to produce antibodies that overstimulate the thyroid. This leads to an overproduction of thyroid hormones. Graves’ disease may cause the thyroid gland to visibly enlarge in the front of the neck, a condition called a goiter. Graves’ disease tends to run in families and is more common in women.
Toxic adenomas
Solitary hyperfunctioning nodules in the thyroid called toxic adenomas can also cause excess thyroid hormone release. Toxic adenomas are not cancerous but can continue to grow and produce too much thyroid hormone. They are more common as people age.
Thyroiditis
Thyroiditis refers to inflammation of the thyroid gland. This can release excess thyroid hormones into the bloodstream until the thyroid’s hormone production stabilizes. Different types of thyroiditis include Hashimoto’s thyroiditis, subacute thyroiditis, silent thyroiditis, postpartum thyroiditis, and drug-induced thyroiditis.
Excess iodine intake
Consuming too much iodine can overstimulate hormone production and cause hyperthyroidism. Sources of excess iodine include certain medications like amiodarone, radiologic contrast agents, dietary supplements, and kelp. This type of hyperthyroidism is usually temporary.
Pituitary gland disorders
In very rare cases, tumors on the pituitary gland can cause overproduction of thyroid-stimulating hormone, leading to excessive thyroid hormone release.
Risk factors for hyperthyroidism
Several factors can increase the risk of developing hyperthyroidism:
– Family history – Having a close relative with an autoimmune thyroid disorder means you are more genetically prone.
– Age – Graves’ disease most often affects people under 40, especially women. Toxic nodules become more common in those over 40.
– Sex – Women are up to 10 times more likely to develop Graves’ disease than men.
– Pregnancy – Hyperthyroidism can occur during or after pregnancy.
– Medical history – People with other autoimmune disorders like type 1 diabetes or pernicious anemia are at higher risk. Those with a past thyroid inflammation or goiter may also be predisposed.
– Radiation exposure – Radiation treatment to the neck or chest can increase risk years later.
Signs and symptoms of hyperthyroidism
The symptoms of hyperthyroidism result from the increased metabolism caused by excess thyroid hormones in the body. Typical signs and symptoms include:
Nervousness, anxiety, and irritability
Abnormally high thyroid hormone levels can simulate the body’s “fight or flight” response, leading to excessive anxiety, nervousness, and irritability. People may be jittery and emotional.
Unexplained weight loss
Rapid metabolism from thyroid hormones burns calories, causing substantial weight loss even with a good appetite. Losing more than 5% of body weight without dieting is a common hyperthyroidism symptom.
Rapid or irregular heartbeat
Thyroid hormones speed up the heart rate and can cause palpitations, a feeling like your heart is pounding or racing. Atrial fibrillation is a type of abnormal heart rhythm seen in hyperthyroidism.
Increased sweating
The ramped-up metabolism causes increased sweating and intolerance of heat. Many people notice excessive sweating or feeling too hot in warm environments.
Loose stools
Having frequent bowel movements or diarrhea is another sign of a revved-up metabolism. Thyroid hormones increase gut motility.
Muscle weakness
Even though the metabolism speeds up, muscle tissue can start to break down. Weakness or tiredness, especially in the upper arms and thighs, is characteristic.
Hair loss
Temporary hair thinning or loss of hair can occur as more hair follicles shift into the resting phase. Hair typically regrows with treatment.
Lethargy
Despite the signs of increased metabolism like weight loss and rapid heart rate, some patients paradoxically experience fatigue and low energy.
Other symptoms
Additional signs of hyperthyroidism include tremor, especially in the hands, increased appetite, more frequent bowel movements, scant or light menstrual periods, impaired fertility, thyroid gland enlargement or goiter, eye changes like retraction or staring gaze, and sleep troubles like insomnia.
Complications of untreated hyperthyroidism
Leaving hyperthyroidism untreated for a prolonged period can lead to complications:
Irregular heartbeat
Continuously rapid heart rate from excess thyroid hormones increases the risk of abnormal heart rhythms like atrial fibrillation. This can lead to blood clots, stroke, or heart failure.
Heart problems
In addition to arrhythmias, overactive thyroid can cause high blood pressure and even chest pain or angina. Excess strain on the heart increases the risk of heart attack or heart failure.
Brittle bones
Too much thyroid hormone leads to increased bone turnover and calcium loss, weakening bones. Untreated hyperthyroidism substantially increases fracture risk.
Thyroid storm
Rarely, hyperthyroidism that gets rapidly worse and out of control can culminate in thyroid storm. This is a sudden, life-threatening exacerbation of symptoms that requires emergency treatment.
Birth complications
Untreated hyperthyroidism in pregnant women is associated with an increased risk of miscarriage, preterm birth, preeclampsia, low birth weight, stillbirth, and birth defects. Prompt treatment is needed.
Who should be screened for hyperthyroidism?
Since hyperthyroidism can cause nonspecific symptoms like unexplained weight loss, fatigue, and rapid heart rate, doctors may perform screening blood tests in the following groups:
– People over age 60, when hyperthyroidism is more common
– Patients with known risk factors like family history or other autoimmune disorders
– Pregnant women, since maternal hyperthyroidism can affect the fetus
– Those with signs of goiter or thyroid nodules found on physical exam
– Individuals with unintentional weight loss, persistent tachycardia, tremors, or newly diagnosed atrial fibrillation or osteoporosis
Diagnosing hyperthyroidism
Hyperthyroidism is diagnosed through blood tests, imaging, and sometimes biopsy:
TSH test
The main screening test is a TSH or thyroid-stimulating hormone test. Low TSH levels below the normal range indicate that the thyroid is overactive and hyperthyroidism is likely.
T4 and T3 testing
If TSH is low, your doctor will order tests for free T4 and total T3 levels. High output of these thyroid hormones confirms hyperthyroidism. This helps determine the severity.
Thyroid scan
Radioactive iodine or technetium uptake imaging helps visualize thyroid activity. Increased uptake indicates overactivity consistent with hyperthyroidism. Scans aid in determining the underlying cause.
Thyroid antibody tests
Measuring thyroid antibodies, like thyroid peroxidase and thyroglobulin antibodies, can help diagnose autoimmune causes like Graves’ disease.
Biopsy
If nodules or goiter are present, your doctor may take a biopsy to rule out thyroid cancer. This is important since some thyroid cancers can also cause hyperthyroidism.
Who gets treated for hyperthyroidism?
Treatment is recommended for all patients with confirmed hyperthyroidism, except in special cases:
– **Subclinical hyperthyroidism** – With TSH low but T3 and T4 still normal, your doctor may monitor you before starting treatment.
– **Transient hyperthyroidism** – If an infection, pregnancy, or medication caused a temporary hyperthyroidism that resolves, you may not require treatment.
– **Thyroiditis** – Treatment may not be needed if it is silent or postpartum thyroiditis that will stabilize on its own.
– **Older adults** – Treatment in patients over 80 to 85 may depend on symptoms, risks, and complications since hyperthyroidism sometimes resolves on its own in this population.
Otherwise, treatment helps resolve hyperthyroidism’s symptoms, minimize complications, and prevent long-term consequences of excess thyroid hormone exposure.
Treatment options for hyperthyroidism
There are three main approaches to treating hyperthyroidism:
Antithyroid medications
Medications like methimazole and propylthiouracil block thyroid hormone production and reduce thyroid levels. This provides rapid relief of symptoms but may take several months to achieve full effect. Medications often treated until thyroid levels normalize, but 50% of patients eventually relapse when stopped. Side effects include rash, joint pain, nausea, and liver problems.
Radioactive iodine therapy
Taking radioactive iodine by mouth intentionally damages and shrinks the overactive thyroid tissue to reduce excess hormone production. Effects may take 6-18 weeks to become evident. It often leads to permanent hypothyroidism requiring daily thyroid hormone replacement therapy. Rare side effects include neck tenderness, nausea, and dry mouth.
Surgery
Surgical removal of part or all of the thyroid eliminates the source of excess hormone production. This leads to rapid improvement in hyperthyroidism. Risks include bleeding, infection, vocal cord paralysis, hypoparathyroidism or hypothyroidism.
The best treatment option depends on the underlying cause, severity, other medical conditions, patient age, cost, and personal preferences. Your doctor can help you weigh the pros and cons of each therapy.
What is the usual treatment course for hyperthyroidism?
The typical treatment course for hyperthyroidism is:
1. **Diagnosis** – Hyperthyroidism testing through blood work and imaging to confirm overactive thyroid. Determining the cause helps guide treatment.
2. **Control and monitoring** – For most patients, starting an antithyroid medication like methimazole or propranolol for rapid symptom improvement. Regular lab testing and appointments to monitor thyroid levels.
3. **Maintenance** – Staying on medications until TSH, T4, and T3 levels normalize, typically 3-12 months or longer. Patients feel better but are not cured on medications alone.
4. **Definitive treatment** – Once stabilized on medications, choosing a radioactive iodine treatment or thyroid surgery for a permanent fix to hyperthyroidism. This prevents relapse when stopping medications.
5. **Follow-up care** – Lifelong monitoring of thyroid levels, especially if hypothyroidism requiring thyroid hormone replacement results from treatment. Managing any long-term complications.
The treatment time frame varies from several months to achieve remission with medications alone up to 12-18 months for radioactive iodine results. A coordinated team approach leads to the best outcomes.
What triggers hyperthyroidism relapse?
Even after treatment, some factors can trigger a recurrence of hyperthyroidism:
– **Stopping antithyroid medications** – Around half of patients have a relapse after finishing a medication like methimazole. The longer the medication is taken, the lower the recurrence rate.
– **Poor medication adherence** – Inconsistent use of antithyroid drugs allows thyroid levels to fluctuate, increasing relapse risk. Sticking to your prescribed regimen prevents this.
– **Underlying Graves’ disease** – Graves’ disease as the cause of hyperthyroidism makes relapse more likely since the autoimmune dysfunction may persist.
– **Large goiter** – A thyroid goiter over 80 grams is associated with increased recurrence risk after antithyroid medications are stopped.
– **High initial hormone levels** – Relapse is more common when pre-treatment thyroid hormone levels are very elevated vs mildly increased.
– **Radioactive iodine dose** – Receiving a low or inadequate dose of radioactive iodine to treat hyperthyroidism makes recurrence more probable.
– **Stress** – High stress levels may re-trigger hyperthyroidism in those predisposed to overactivity of the thyroid.
Careful monitoring and follow-up testing helps detect and manage relapses early before symptoms escalate. Identifying those at higher risk guides preventive therapy.
What is the prognosis with hyperthyroidism treatment?
With treatment, most people with hyperthyroidism have an excellent prognosis and life expectancy similar to the general population. However, prognosis depends on:
– **Cause** – Graves’ disease has higher relapse risk after treatment than other causes like solitary thyroid nodules.
– **Severity** – If thyroid hormone levels were extremely high at diagnosis, there is increased risk of residual complications.
– **Coexisting conditions** – Presence of high blood pressure, heart disease, or eye disease from hyperthyroidism can worsen prognosis.
– **Age** – Being younger at diagnosis leads to better outcomes. Treatment is generally more effective before age 50.
– **Treatment** – Definitive therapy like radioactive iodine or surgery has better long-term cure rates than antithyroid medications alone.
– **Follow-up care** – Consistent monitoring and taking thyroid hormone replacement as prescribed after ablation prevents complications.
With treatment guided by the cause and clinical features, most hyperthyroid patients live symptom-free lives without limitations. Cure from ablation therapy is around 85-95% if medication directions are properly followed long-term.
What steps can you take to manage hyperthyroidism?
Self-care measures that help manage hyperthyroidism include:
– **Take medications consistently** – Antithyroid drugs work best when taken daily as prescribed. Don’t adjust the dose or stop without your doctor’s supervision.
– **Get regular lab testing** – Routine blood work helps ensure thyroid levels normalize and detect recurrence early.
– **Eat a balanced diet** – Eat fruits, vegetables, whole grains, and lean proteins. Avoid excess iodine. Steer clear of raw cruciferous veggies which can affect thyroid function.
– **Stay hydrated** – Drink plenty of water. Dehydration worsens hyperthyroidism symptoms.
– **Use cool compresses** – Applying cold cloths helps minimize sweating, flushing, and feeling overtly hot.
– **Exercise regularly** – Low to moderate activity like walking helps manage stress. Avoid exhaustive workouts which can aggravate symptoms.
– **Reduce caffeinated or sugary drinks** – Limit coffee, tea, soda, and energy drinks that can amplify symptoms.
– **Decrease stress** – Try relaxation techniques like yoga and meditation. Stress management boosts treatment effectiveness.
– **Use sun protection** – Sunscreen minimizes sun exposure that can worsen hyperthyroidism for some patients.
– **Keep follow-up appointments** – Regular visits to monitor response to treatment are key. Report any medication side effects promptly.
Conclusion
In summary, the hallmark sign of hyperthyroidism is a low serum TSH level, indicating overactivity of the thyroid gland and overproduction of thyroid hormones. Causes include Graves’ disease, toxic thyroid nodules, thyroiditis, and excess iodine intake. Symptoms stem from a revved-up metabolism. While hyperthyroidism is treatable in most patients with medications, radioactive iodine, or surgery, uncontrolled hyperthyroidism can lead to complications including heart rhythm abnormalities, brittle bones, and thyroid storm. Careful long-term monitoring and follow-up testing helps manage the condition optimally and prevent recurrences. With the right treatment guided by a patient’s specific situation, those with hyperthyroidism can achieve an excellent prognosis and live full lives. Consult your doctor if you are concerned you may be experiencing symptoms of hyperthyroidism. Prompt diagnosis and treatment provides the best path to getting your thyroid levels back on track.