Hyperthyroidism is an overactive thyroid. The condition develops when the thyroid gland produces too much T3 and T4 hormone, driving up metabolism and causing a variety of symptoms and health problems.

Sudden Weight Loss

High levels of thyroxine hormone can cause sudden weight loss without an apparent cause. This increase in T3 and T4 hormones in the blood raises the metabolic rate, causing the affected person to more quickly burn food for energy. Though this might seem appealing initially, high-speed absorption and elimination mean the body cannot receive all the nutrients the food has to offer, leading to deficiencies and various symptoms. The body might, for example, start cutting into fat reserves, which causes fatigue. Sudden, unexplained weight loss always calls for a visit to the doctor.



People with hyperthyroidism often get tremors -- involuntary and uncontrollable shaking of the hands. This shows up most clearly when gesturing, gripping, and carrying out precision work such as sewing. Hand tremors occur at random intervals and may subside on their own, without treatment.



A goiter is a painless swelling of the thyroid gland that occurs when the gland is overactive or underactive. The whole neck can become enlarged, a visible sign that often causes the person to feel self-conscious. While goiters are not usually painful, large growths can cause a cough, as well as problems with swallowing and breathing. A doctor should investigate any swelling in the neck; medication can often control this symptom of hyperthyroidism.


Frequent Bowel Movements

The secretion of excess thyroid hormone speeds up the GI tract and digestion, causing more waste production and, as such, more frequent bowel movements. Most people with hyperthyroidism experience the urge to void their bowels multiple times a day, especially after eating.


Excessive Sweating

An overworked thyroid can lead to excess perspiration — the slightest exertion, even light activity around the home, can trigger sweating. People with hyperthyroidism need to be mindful of dehydration, especially in hot locations. Some people with high thyroid activity eventually become heat intolerant. However, excess sweating is a symptom that hyperthyroidism treatments can help manage.


High Heart Rate and Palpitations

Changing levels of thyroid hormone can also change the way the nervous system works, subsequently affecting the heart. People with hyperthyroidism can experience a rapid heart rate and palpitations. It is not uncommon for the heart rate to rise above 90 beats per minute, even at rest. Medications can slow heart rate in affected individuals.


Changes to the Menstrual Cycle

Women with an overactive thyroid often see changes in their monthly cycle. They may have abnormally light bleeding or long gaps between periods. Periods may become irregular, or not occur at all some months. This is one of the most common signs of a thyroid issue in women. Once beginning treatment for hyperthyroidism, menstruation should return to normal within a few months.


Hair Loss

An overactive thyroid affects many body systems and areas, including the hair. People with hyperthyroidism can experience hair thinning and loss, which typically develops in severe cases or those where the thyroid has gone untreated for some time. The thinning can affect the entire scalp, sometimes causing hair loss in the eyebrows, as well. Like most other symptoms, treatment may relieve this sign.



People with hyperthyroidism often have problems sleeping. They may develop mild to moderate insomnia, either having difficulty falling asleep or experiencing low-quality sleep. The symptoms may gradually worsen over time. Not enough sleep causes distraction and an absent mind, as well as irritation and fatigue. General weakness and muscle aches can also result from poor sleep.



Due to its interaction with chemicals in the brain, the thyroid hormone can affect mood in some odd ways. People with an overactive thyroid can feel anxious without an obvious cause, or have panic attacks in situations that wouldn't normally trigger them. Many conditions can cause unexpected fluctuations in mood, however, so it is always best to see a doctor and receive a diagnosis.



People with a hyperactive thyroid often seem on edge and may show signs of nervousness and too much energy. They can have trouble sitting still or find their attention wandering. These symptoms can also interfere with sleep. In some cases, a hyperactive thyroid may be mistaken for an anxiety disorder.


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