Thyroid disorders are shockingly common, affecting 20 million people in the United States alone. Hyperthyroidism, a condition characterized by an overactive thyroid gland, is estimated to affect 1-3% of the U.S. population. However, many cases go undiagnosed and untreated, as the early warning signs can be subtle and easily mistaken for other health issues.
Recognizing these signs is a crucial first step for patients seeking prompt medical attention and healthcare providers initiating the appropriate diagnostic workup. With the proper treatment, affected patients can avoid the potentially devastating complications that can arise from hyperthyroidism, including blood clots, osteoporosis, and fertility issues (just to name a few).
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What Is Hyperthyroidism?
The thyroid gland is a small, butterfly-shaped organ located at the front of the neck that makes and releases thyroid hormones called thyroxine (T4) and triiodothyronine (T3). Thyroid hormones influence nearly every organ system, affecting the following bodily functions:
- Metabolism and body weight
- Heart rate
- Breathing
- Digestion
- Body temperature
- Nervous system
- Reproduction
- Muscle and bone strength
- Immunity
Hyperthyroidism, or overactive thyroid, occurs when the thyroid gland makes too much thyroid hormone. The excessive levels of T3 and T4 accelerate metabolic processes throughout the body, resulting in the signs and symptoms of hyperthyroidism.
Common Early Symptoms of Hyperthyroidism
The symptoms of hyperthyroidism can mimic those of other conditions, making it tricky to diagnose. Here are some of the most common early symptoms of hyperthyroidism to watch out for:
Unintentional Weight Loss
People with hyperthyroidism may lose weight without trying. In some cases, this occurs despite also experiencing an increased appetite. (56)
Hyperthyroidism causes an increase in the following (46):
- Basal metabolic rate
- Heat production
- Energy expenditure
In other words, hyperthyroidism causes the body to burn calories (energy) faster than normal, creating a caloric deficit that can lead to weight loss.
Rapid or Irregular Heartbeat
Thyroid hormones make the heart work harder and faster. These hormones stimulate the heart's pacemaker, known as the sinoatrial node, leading to an increased heart rate (tachycardia), defined by a resting heart rate above 100 beats per minute. (42)
Additionally, elevated thyroid hormone levels enhance the strength of each heartbeat by increasing the contractility of the heart muscle, which means the heart pumps more blood with each contraction. (42)
This heightened activity demands more oxygen and nutrients, placing significant stress on the cardiovascular system. Over time, this can result in complications such as abnormal heart rhythms (arrhythmias), skipped heartbeats (palpitations), high blood pressure (hypertension), and even heart failure if left untreated. (29)
Nervousness, Anxiety, and Irritability
Hyperthyroidism can lead to symptoms of anxiety, irritability, and nervousness, often mimicking anxiety disorders such as generalized anxiety disorder (GAD) or panic disorder.
This overlap occurs because the excessive production of thyroid hormones accelerates metabolic processes and heightens the body's sympathetic ("fight or flight") nervous system activity, resulting in physical symptoms like rapid heartbeat, tremors, sweating, and restlessness.
Evidence indicates that individuals with hyperthyroidism are more likely to exhibit anxiety symptoms compared to those with normal thyroid function. For instance, one study found that 60% of hyperthyroid patients displayed signs of psychiatric disorders, including GAD, panic attacks, and major depressive disorder (MDD).
Tremors and Shaky Hands
Tremor is a symptom in 76% of patients with excessive amounts of circulating thyroid hormones.
Thyroid hormones amplify catecholamine signaling. Catecholamines, including adrenaline, noradrenaline, and dopamine, are a group of hormones made by the adrenal glands that help your body respond to stress or danger by increasing heart rate, blood pressure, and breathing rate. Overactivity can lead to involuntary shaking or trembling. (36)
Changes in Energy Levels and Sleep Patterns
While it may seem like a faster metabolism would increase energy levels, many people with hyperthyroidism actually feel more tired. This is because the constant metabolic boost overworks the body, leading to persistent mental and physical fatigue. (5)
Insomnia is a sleep disorder that makes it difficult to fall, stay, or get quality sleep. Unfortunately, as many as 66% of patients with hyperthyroidism have trouble falling asleep, potentially exacerbating fatigue.
Physical Symptoms of Hyperthyroidism
Hyperthyroidism can lead to a range of physical symptoms due to increased metabolism.
Increased Sweating and Heat Intolerance
Individuals with hyperthyroidism often experience heat intolerance, hot flashes, and excessive sweating. Elevated thyroid hormone levels accelerate the body's metabolic processes, generating more heat. As metabolism speeds up, the body works harder to cool itself, increasing perspiration.
Frequent Bowel Movements or Diarrhea
Rapid metabolic rate can speed up gastrointestinal motility, causing food to move through the intestines more quickly than normal. This can result in diarrhea (frequent and/or loose bowel movements).
Other digestive symptoms that can occur with hyperthyroidism include (59):
- Abdominal pain
- Difficulty swallowing
- Low stomach acid (hypochlorhydria)
- Nausea
- Vomiting
Changes in Skin and Hair
Thyroid hormones are involved in the growth, proliferation, and shedding of skin and hair cells, so it's unsurprising that many skin diseases are associated with thyroid dysfunction (17).
Common dermatologic manifestations of hyperthyroidism include:
- Thin, warm skin
- Fine, brittle hair
- Diffuse hair shedding
- Shiny, soft, and brittle nails
Menstrual and Reproductive Changes
The hypothalamic-pituitary-thyroid (HPT) and hypothalamic-pituitary-ovarian (HPO) axes are interconnected hormonal signaling systems that regulate thyroid and reproductive function (24).
Excess thyroid hormones can lead to HPO axis dysfunction, which negatively impacts ovarian function and causes hormonal imbalances (1).
Hyperthyroidism can also cause high levels of sex hormone-binding globulin (SHBG), a protein that regulates the availability of sex hormones. Abnormal SHBG levels can further contribute to hormonal dysregulation.
Common symptoms related to these imbalances include (24, 30):
- Lighter menstrual periods
- Fewer menstrual periods (oligomenorrhea)
- Anovulatory menstrual cycles, where ovulation does not occur
Irregular and anovulatory menstrual cycles can lead to fertility problems in women.
Eye-Related Symptoms (Graves' Disease)
Graves' disease is an autoimmune, and most common, form of hyperthyroidism that occurs when the immune system makes antibodies that cause the thyroid to overproduce thyroid hormones.
Graves' disease may cause swelling and inflammation behind the eyes, leading to Graves' eye disease (or Graves' ophthalmopathy). Symptoms include:
- Bulging eyes (exophthalmos)
- Dry, gritty, red eyes
- Eye pain or pressure
- Eyelids are puffy or don't close all the way
- Double vision
- Sensitivity to light
Additional Signs to Watch For
A goiter is an abnormally enlarged thyroid gland, which various factors, including an overactive thyroid, can cause. Goiters can be problematic because they may put excessive pressure on the neck and throat, leading to symptoms such as:
- A persistent feeling of a lump or obstruction in the throat
- Difficulty swallowing or breathing
- Cough
- Changes in voice
Thyrotoxic myopathy is a muscle condition that can occur in people with hyperthyroidism. Symptoms include:
- Muscle weakness
- Muscle pain and tenderness
- Difficulty performing tasks like climbing stairs, lifting objects, or raising arms
In severe cases, thyrotoxic myopathy is associated with rhabdomyolysis, which is an acute breakdown of muscle tissue. This is a serious condition that requires immediate medical attention. (55)
When to See a Doctor
If you have one or more risk factors for hyperthyroidism or develop any of its related symptoms, talk to your doctor.
You may be at a higher risk for developing hyperthyroidism if you are:
- Female
- Over age 60
- Have a family history of thyroid problems
- Consume too much iodine
- Have been pregnant within the last six months
Diagnosis and Next Steps
To diagnose hyperthyroidism, your doctor will take a comprehensive personal and family medical history and perform a physical exam.
They will also order labs to measure the levels of thyroid-related hormones and antibodies in the blood. These include:
- Thyroid-stimulating hormone (TSH)
- T4 (free and total)
- T3 (free and total)
- Thyroid antibodies (thyrotropin receptor antibody, anti-thyroid peroxidase, and anti-thyroglobulin)
Having low TSH with high T4 and T3 is diagnostic for hyperthyroidism. Patients with Graves' disease will also have elevated thyrotropin receptor antibodies. (35)
A radioactive iodine uptake test and thyroid scan examine the thyroid gland's size, structure, and function, helping to determine the cause of hyperthyroidism. Your doctor may order a thyroid ultrasound as a cost-effective imaging alternative if you have a contraindication for the thyroid scan and uptake test. (36)
Treatment for hyperthyroidism can look different for different people, but common treatment options include:
- Medications to reduce thyroid hormone levels (propylthiouracil or methimazole)
- Medications to control symptoms of hyperthyroidism (beta-blockers)
- Radioiodine therapy to destroy overactive thyroid cells
- Surgery to remove part or all of your thyroid gland
Patients can work with an integrative endocrinologist trained to conduct a more comprehensive evaluation to uncover the underlying causes of hyperthyroidism. Then, they can develop a personalized treatment plan that addresses these imbalances and supports thyroid health more holistically.
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Key Takeaways
- Early recognition of the signs of hyperthyroidism is key for the effective management of this endocrine disorder and the prevention of serious health complications.
- Symptoms such as increased heart rate, weight loss, anxiety, and menstrual irregularities can often be overlooked or attributed to other conditions.
- Don't hesitate to advocate for your health if you suspect a thyroid issue may be causing your symptoms! Early detection through simple blood tests can lead to timely treatment and get your health back on track.
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