Hyperthyroidism is characterized by the activation of sympathetic nervous system [3]. The common symptoms of hyperthyroidism include:

• Weight loss with increased appetite
• Increased sweating
• Heat intolerance
• Anxiety and nervousness
• Palpitations
• Irritability
• Muscle weakness and easy fatigability
• Menstrual abnormalities
• Changes in bowel patterns
• Fine tremors in the patient’s hands and feet

Older adults usually either have no symptoms, or have only subtle ones such as increased heart rate, easy fatigability and heat intolerance.

• Goiter

  In the patients with goiter, hyperthyroidism and symptoms of exophthalmos, and the patients with goiter, hyperthyroidism without symptoms of exophthalmos, IL-2 and TGF-β expression level were not different (p > 0.05). [ncbi.nlm.nih.gov]

  Toxic multinodular goiter: 60% of the cases of toxic multinodular goiter are caused by defects in the TSH (thyroid stimulating hormone) receptor gene. In 40% of the cases, the cause is unknown. [symptoma.com]

  Toxic multinodular goiter Toxic multinodular goiter (Plummer disease) accounts for 15-20% of thyrotoxicosis cases (see the image below). It occurs more commonly in elderly individuals, especially those with a long-standing goiter. [emedicine.com]

  A goiter or nodule may be present. [merck.com]

• Weight Loss

  If you have been diagnosed with hyperthyroidism, then you may have noticed some changes in your body, from unexplained weight loss to fatigue and tremors. [healthhub.sg]

  A 28-year-old woman presented with weight loss and tiredness. Investigations revealed hyperthyroidism. She was commenced on treatment and later became pregnant. [ncbi.nlm.nih.gov]

  Symptoms include a fast heart rate, high blood pressure, and weight loss Blood tests can confirm you have hyperthyroidism Medicines can usually help with hyperthyroidism Hyperthyroidism happens in about 1 out of every 100 people Thyroid storm is very [merckmanuals.com]

  When the thyroid gland is overactive ( hyper thyroidism) the body’s processes speed up and you may experience nervousness, anxiety, rapid heartbeat, hand tremor, excessive sweating, weight loss, and sleep problems, among other symptoms. [endocrineweb.com]

• Weakness

  Neurological examination showed weakness in the muscles of the bilateral upper and lower limbs. Muscle weakness was more severe in the proximal site than in the distal site. [ncbi.nlm.nih.gov]

  […] are the same as those of regular hyperthyroidism but more severe, including: High fever Extreme weakness Restlessness and confusion Passing out Shock (a dangerous drop in blood pressure) Treatment depends on the cause of the hyperthyroidism. [merckmanuals.com]

• Fatigue

  It is the largest study to date of this population and will help mental health ... read more Chronic Fatigue Syndrome Possibly Explained by Lower Levels of Key Thyroid Hormones Mar. 20, 2018 — A new study reveals that chronic fatigue syndrome, a debilitating [sciencedaily.com]

  If you have been diagnosed with hyperthyroidism, then you may have noticed some changes in your body, from unexplained weight loss to fatigue and tremors. [healthhub.sg]

  Increased energy (hyperactivity) Fatigue Unexplained weight loss Trouble sleeping Inability to tolerate heat Trouble concentrating in school Diarrhea Fast, pounding heartbeat Bulging eyes Irregular periods Shaking Hyperthyroidism can be treated by taking [cincinnatichildrens.org]

  We report the case of a 33-year-old euthyroid woman who presented to our hospital with palpitation, hand tremor, fatigue, and excessive sweating after HSG. [ncbi.nlm.nih.gov]

• Fever

  Familial Mediterranean fever (FMF) is a genetic autoinflammatory disorder characterized by serositis and recurrent fever. [ncbi.nlm.nih.gov]

  Patients typically appear markedly hypermetabolic with high fevers, tachycardia, nausea and vomiting, tremulousness, agitation, and psychosis. Late in the progression of disease, patients may become stuporous or comatose with hypotension. [web.archive.org]

• Failure to Thrive

  Congenital hyperthyroidism can be a cause of failure to thrive, hyperactivity, developmental delay, and craniosynostosis during infancy. Most commonly, the condition occurs in the setting of maternal autoimmune thyroid disease. [ncbi.nlm.nih.gov]

  Other symptoms include failure to thrive, vomiting, and diarrhea. The newborn, like the mother, may have bulging eyes (exophthalmos). [merckmanuals.com]

• Polydipsia

  Clinical features Early symptoms : anxiety, palpitations, rapid pulse, fatigue, muscle weakness, weight loss, diarrhea, hyperactive reflexes, increased sweating, heat intolerance, warm skin, excessive perspiration, menstrual changes, hand tremor, polydipsia [pathologyoutlines.com]

• Palpitations

  A 22-year-old lactating mother presented with symptoms of uneasiness, palpitation, tachycardia and exophthalmos. She had an abdominal lump suggestive of 26 weeks uterine size but her urine pregnancy test was negative. [ncbi.nlm.nih.gov]

  You could also be prescribed medicine to control a fast heart rate and palpitations, or medicine for your eyes if these are affected by Graves’ Disease. [healthdirect.gov.au]

  Any time someone experiences strange sensations they run the risk of developing nervousness and anxiety as a result, especially if some of those symptoms,like heart palpitations, are frightening. [calmclinic.com]

  Are you having crippling panic attacks, complete with heart palpitations, breathlessness, and constant sweating? It may feel as if you’re losing your mind. But, in fact, you may be suffering from hyperthyroidism. [holtorfmed.com]

• Heart Failure

  Excess thyroid hormone affects cardiovascular hemodynamics, leading to high-output heart failure and, in late stages, dilated cardiomyopathy. [ncbi.nlm.nih.gov]

  By forcing the heart to work harder and faster, an overactive thyroid can overtax it and cause heart failure, a condition in which the heart can't pump enough blood to meet the body's needs. [health.harvard.edu]

  Treatment may include: Medication that blocks the production of thyroid hormones and treats rapid heart rate Treatment for heart failure [stanfordchildrens.org]

• Tachycardia

  Clinical features of fetal hyperthyroidism include tachycardia, goiter, growth restriction, advanced bone maturation, cardiomegaly, and fetal death. [ncbi.nlm.nih.gov]

  Beta-blockers, such as atenolol or propranolol, may be used to control hypertension and tachycardia. [merckmanuals.com]

• Hypertension

  KEYWORDS: Hashimoto's thyroiditis; hyperthyroidism; pregnancy; systolic arterial hypertension [ncbi.nlm.nih.gov]

  Beta-blockers, such as atenolol or propranolol, may be used to control hypertension and tachycardia. [merckmanuals.com]

• Mitral Valve Prolapse

  Retrieved August 10, 2019. ^ "Mitral Valve Prolapse". Mayo Clinic. March 6, 2018. Retrieved August 9, 2019. ^ "Acute myocardial infarction: Role of beta blocker therapy". www.uptodate.com. [en.wikipedia.org]

• Diplopia

  […] problems such as proptosis, conjunctival oedema, or ophthalmoplegia—and the dreaded complication of optic nerve compression is mercifully rare. 1 When it does occur, however, severe thyroid eye disease is difficult to treat and may result in disfigurement, diplopia [doi.org]

  They may also notice diplopia or double vision. This is due to entrapment of the muscles. The eyes may become irritated and red: conjunctivitis. There may be periorbital edema, upper lid retraction, or lower lid retraction. [web.archive.org]

  […] diarrhea Lower leg swelling Sudden paralysis Shortness of breath with exertion Decreased menstrual flow Impaired fertility Sleep disturbances (including insomnia ) Changes in vision Photophobia, or light sensitivity Eye irritation with excess tears Diplopia [emedicinehealth.com]

  In severe cases, blurred vision, diplopia, or reduced color perception may develop. 16 Smoking increases the risk of developing Graves orbitopathy (odds ratio = 3.7). 17 Pretibial myxedema, a less common finding, develops from fibroblast activation and [aafp.org]

• Muscle Weakness

  She presented with muscle weakness, nausea, vomiting, and diarrhea since one week. The initial diagnosis was TPP. However, biochemistry tests showed hypokalemia with metabolic alkalosis and renal potassium wasting. [ncbi.nlm.nih.gov]

  These include: Increased heart rate Hand tremor Brisk response to tapping with a reflex hammer Excessive sweating Muscle weakness Protruding eyes If your doctor suspects hyperthyroidism, he or she will order blood tests. [drugs.com]

  They may include Being nervous or irritable Mood swings Fatigue or muscle weakness Heat intolerance Trouble sleeping Hand tremors Rapid and irregular heartbeat Frequent bowel movements or diarrhea Weight loss Goiter, which is an enlarged thyroid that [medlineplus.gov]

• Advanced Bone Age

  Children and adolescents may present with alterations in growth, including growth acceleration and advanced bone age; however, puberty is often delayed rather than precocious. [merckmanuals.com]

• Muscle Cramp

  cramps Dry skin Goiter (swelling of thyroid gland) Brittle nails Slow heart rate Irregular period Sensitivity to cold Constipation Carpal tunnel syndrome Treatment for hypothyroidism Levothyroxine sodium tablets (aka Synthroid) can be taken once a day [piedmont.org]

• Sweating

  After tracheal extubation, the patient exhibited abnormal tachycardia, agitation, sweating, and hyperpyrexia. The clinical manifestation and the following thyroid function test indicate a high index of suspicion for impending thyroid storm. [ncbi.nlm.nih.gov]

  This leads to a wide range of symptoms including weight loss, increased appetite, increased sweating, intolerance to heat, anxiety and irritability. Hyperthyroidism can be treated by drugs, surgery or radiation. [symptoma.com]

  Hyperthyroid patients typically experience symptoms such as anxiety, insomnia, weight loss, rapid heartbeat, sweating, diarrhea, and eye or vision changes. [holtorfmed.com]

  While you’re pregnant, it’s tough to tell if your thyroid is acting up or if the excessive sweating and vomiting are just from being pregnant. [thebump.com]

• Increased Sweating

  This leads to a wide range of symptoms including weight loss, increased appetite, increased sweating, intolerance to heat, anxiety and irritability. Hyperthyroidism can be treated by drugs, surgery or radiation. [symptoma.com]

  Typical symptoms of the condition include: Nervousness and irritability Increased resting heart rate, which causes heart palpitations Heat intolerance and increased sweating Tremors Weight loss with increase in appetite Frequent bowel movements Thyroid [ucsfhealth.org]

  Feeling too hot Increased sweating Muscle weakness Trembling hands Rapid heartbeat Tiredness/fatigue Weight loss Diarrhea or frequent bowel movements Irritability and anxiety Eye problems, such as irritation or discomfort Menstrual irregularities Infertility [hormone.org]

• Flushing

  […] symptoms that can occur with this disease: Breast development in men Clammy skin Diarrhea Feeling faint when you raise your hands High blood pressure Itchy or irritated eyes Itchy skin Nausea and vomiting Protruding eyes (exophthalmos) Skin blushing or flushing [pennmedicine.org]

  For 3 days after treatment with RAI, patient should double flush his toilet and wash his hands often. One should also avoid contact with young children and pregnant women during this time, to avoid harmful effects by radioactivity. [flexikon.doccheck.com]

  Tachycardia Hyperactivity Thyromegaly Other signs and symptoms include the following Prematurity Small for gestational age Poor weight gain despite a voracious appetite Irritability Poor sleep Hypertension Proptosis with lid retraction and stare Warm, flushed [clinicaladvisor.com]

• Dry Skin

  skin Gaining weight too quickly Low energy / activity level Abnormal menstrual cycles Never change a medication dose on your own. [cincinnatichildrens.org]

  […] hair Muscle cramps Dry skin Goiter (swelling of thyroid gland) Brittle nails Slow heart rate Irregular period Sensitivity to cold Constipation Carpal tunnel syndrome Treatment for hypothyroidism Levothyroxine sodium tablets (aka Synthroid) can be taken [piedmont.org]

  • Rough and scaly skin and/or dry, coarse, and tangled hair — If you have perpetually dry skin that doesn't respond well to moisturizing lotions or creams, consider hypothyroidism as a factor. • Hair loss — Women especially would want to pay attention [articles.mercola.com]

  Other symptoms may include a lighter flow during menstrual periods, dry skin and brittle nails. Grave's disease can also affect the muscles that lift the eyelids. When the eyes seem to protrude, this is called exophthalmos. [massagetoday.com]

• Alopecia

  Hyperthyroidism classic high & hot signs and symptoms: constipation, weight gain, cold intolerance, hair loss (alopecia). [youtube.com]

  […] increased appetite increased bowel movements and urination infertility and a loss of interest in sex itchy skin with raised itchy swellings (urticaria) nails become loose menstrual problems in women, especially lighter periods or absence of periods alopecia [medicalnewstoday.com]

  Hair thinning or diffuse alopecia. Urticaria, pruritus. Brisk reflexes. Goitre. Proximal myopathy (muscle weakness ± wasting). Gynaecomastia. Lid lag (may be present in any cause of hyperthyroidism). [patient.info]

• Neck Swelling

  […] of the neck) swelling heavy menstruation slow or stopped menstruation joint pain and muscle aches depression night sweats difficulty concentrating sleep paralysis nightmares altered vision like afterglow blurry vision The First Signs of Hyperthyroid [healdove.com]

• Anxiety Disorder

  Many patients with hyperthyroidism suffer from anxiety syndromes, 8 - 10 including generalized anxiety disorder and social phobia ( Table 1 ). [currentpsychiatry.com]

  These findings provide a ... read more Thyroid Screening May Not Be Needed in All Youth With Psychiatric Disorders Aug. 6, 2019 — A new study looks at the prevalence of abnormal thyroid function in youth with severe mood and anxiety disorder. [sciencedaily.com]

  […] movements or diarrhea Insomnia Weight loss Hair loss Weakness or muscle fatigue Vision changes, including protruding eyes Panic attacks or anxiety disorder And more There’s hope! [holtorfmed.com]

  Social anxiety disorder". The New England Journal of Medicine. 355 (10): 1029–36. doi:10.1056/NEJMcp060145. PMID 16957148. ^ Tyrer P (January 1992). "Anxiolytics not acting at the benzodiazepine receptor: beta blockers". [en.wikipedia.org]

• Loss of Libido

  Loss of libido. Oligomenorrhoea or amenorrhoea. Palmar erythema. Sweaty and warm palms. Fine tremor. Tachycardia - may be atrial fibrillation and/or heart failure (common in the elderly). Hair thinning or diffuse alopecia. Urticaria, pruritus. [patient.info]

• Amenorrhea

  Stenosis, Regurgitation Aortic Stenosis, Regurgitation Cardiomyopathies Myocarditides Constrictive Pericarditis Atrial Fibrillation Infective Endocarditis Aortic Aneurysm Atherosclerosis Hypertension Urinary Tract Infection Pyelonephritis Meningitis Amenorrhea [play.google.com]

• Irritability

  Typical symptoms of the condition include: Nervousness and irritability Increased resting heart rate, which causes heart palpitations Heat intolerance and increased sweating Tremors Weight loss with increase in appetite Frequent bowel movements Thyroid [ucsfhealth.org]

  It occurs when the thyroid becomes irritated. It temporarily causes the thyroid to be overactive. The thyroid then often becomes underactive. Hyperthyroidism may occur for other reasons. [hopkinsmedicine.org]

  […] protruding eyeballs (Grave's disease only) If the person is exhibiting extreme irritability, high blood pressure, rapid heart rate, vomiting, fever up to 106, and delirium, they may have thyroid storm. [healthcentral.com]

• Tremor

  For example, beta-blockers help slow down a rapid heart rate and reduce hand tremors. Updated on: 05/07/19 Hyperthyroidism Symptoms [endocrineweb.com]

  If you have been diagnosed with hyperthyroidism, then you may have noticed some changes in your body, from unexplained weight loss to fatigue and tremors. [healthhub.sg]

  These include: Increased heart rate Hand tremor Brisk response to tapping with a reflex hammer Excessive sweating Muscle weakness Protruding eyes If your doctor suspects hyperthyroidism, he or she will order blood tests. [drugs.com]

• Hyperactivity

  […] or a toxic nodule (when just one nodule is hyperactive). [columbiasurgery.org]

  Congenital hyperthyroidism can be a cause of failure to thrive, hyperactivity, developmental delay, and craniosynostosis during infancy. Most commonly, the condition occurs in the setting of maternal autoimmune thyroid disease. [ncbi.nlm.nih.gov]

  Increased energy (hyperactivity) Fatigue Unexplained weight loss Trouble sleeping Inability to tolerate heat Trouble concentrating in school Diarrhea Fast, pounding heartbeat Bulging eyes Irregular periods Shaking Hyperthyroidism can be treated by taking [cincinnatichildrens.org]

  The ingestion of radioactive iodine shows how quickly the thyroid absorbs iodine (a primary component of thyroxine), along with which parts of the thyroid appear to be hyperactive. [massagetoday.com]

  Beta-blockers: Propranolol 2 mg/kg/d divided in three to four doses/day or atenolol 1-2 mg/kg once daily is the quickest method to control cardiovascular and neuromuscular hyperactivity. [clinicaladvisor.com]

• Insomnia

  […] which causes a thick redness on the front of legs and typically occurs with Graves' disease Thin, delicate skin and irregular fingernail and hair growth Menstrual disturbance, such as decreased flow Mental disturbances Sleep disturbances, including insomnia [ucsfhealth.org]

  A also developed insomnia, depressed mood, and intrusive ego-dystonic thoughts. These symptoms emerged 10 years after a subtotal thyroidectomy for hyperthyroidism (Graves’ disease). [currentpsychiatry.com]

  However, in the longer term, less desirable symptoms, such as muscle weakness, insomnia and trembling can also result. The pulse will likely increase, along with an inability to tolerate heat and abnormally high sweating. [thyroid-info.com]

  Hyperthyroid patients typically experience symptoms such as anxiety, insomnia, weight loss, rapid heartbeat, sweating, diarrhea, and eye or vision changes. [holtorfmed.com]

• Agitation

  After tracheal extubation, the patient exhibited abnormal tachycardia, agitation, sweating, and hyperpyrexia. The clinical manifestation and the following thyroid function test indicate a high index of suspicion for impending thyroid storm. [ncbi.nlm.nih.gov]

  Patients typically appear markedly hypermetabolic with high fevers, tachycardia, nausea and vomiting, tremulousness, agitation, and psychosis. Late in the progression of disease, patients may become stuporous or comatose with hypotension. [web.archive.org]

  […] severity-assessment of Life-Threatening Thyrotoxicosis Temperature: < 37.7 °C / < 99.9 °F 37.8 °C - 38.3 / 100 - 100.9 °F 38.4 - 38.8 °C / 101 - 101.9 °F 38.9 - 39.4 °C / 102 - 102.9 °F 39.5 - 39.9 °C / 103 - 103.9 °F >= 40 °C />= 104 °F CNS Effects: Absent Mild (agitation [formatio-reticularis.de]

  […] excessive ingestion of thyroid hormone ("factitious hyperthyroidism") Includes a wide range of symptoms, such as ophtalmopathy, dermatopathy, fever, marked tachycardia, heart failure, tremor, nausea, vomiting, diarrhea, dehydration, restlessness, extreme agitation [pathologyoutlines.com]

  Psychiatric symptoms seen with hyperthyroidism Anxiety Apathy (more often seen in older patients) Cognitive impairment Delirium Depression Emotional lability Fatigue Hypomania or mania Impaired concentration Insomnia Irritability Mood swings Psychomotor agitation [currentpsychiatry.com]

In addition to complete history, examination and base-line investigations, the following specific set of investigations are helpful in establishing the diagnosis of any thyroid disease [4].

• Serum T3 an T4 levels
• Serum TSH levels
• Iodine uptake
• Thyroid scan
• Ultrasonography

In case of auto-immune thyroiditis, the most specific auto-antibody test is an ELISA (Enzyme Linked Immunosorbent Assay) test for anti-thyroid peroxidase antibody. The titres are significantly increased in case of Grave’s hyperthyroidism, but are very low or absent in case of toxic adenoma or toxic multi-nodular goiter.

Hyperthyroidism is managed by providing symptomatic relief and anti-thyroid therapy, which includes anti-thyroid drugs, radio-active iodine-131 or thyroidectomy.

Anti-thyroid drugs

The drugs commonly used are carbimazole, and propylthiouracil. Both of these drugs interfere with the oxidation of iodides and binding of iodine to tyrosine [5] [6]. 

Advantages:

• No surgery required
• No use of radioactive iodine

Disadvantages:

• Treatment is prolonged (6-24 months)
• Failure rate is 50% and relapses may occur [7]
• Very dangerous side-effect such as agranulocytosis, aplastic anemia and oropharyngeal bacterial infection can occur and may require discontinuation of the drug

Surgery

In toxic and nodular goiter surgery, subtotal or total thyroidectomy cures the disease by reducing the mass of overactive tissue [8]. 

Advantages:

• Cure is rapid
• Cure rate is high

Disadvantages:

• Risk of hypoparathyroidism (5%) [9]
• Risk of recurrent laryngeal nerve injury
• Recurrence of thyrotoxicosis in 5% of patients who were subjected to subtotal thyroidectomy

Radioactive iodine (RAI)

Radioiodine destroys the thyroid cells without surgery. In this treatment, radioactive iodine is given orally which is taken up by the follicles. In the thyroid follicles, beta and gamma rays are emitted from the radioactive iodine which destroys the follicles [10].

Advantages:

• No surgery
• No prolonged drug treatment

Disadvantages:

• Late hypothyroidism

Contraindications:

• Absolute contraindications are pregnancy and breast feeding.
• Relative contraindications include young age, multi-nodularity and Grave’s opthalmopathy.

Hyperthyroidism resulting from toxic multi-nodular goiter and toxic adenoma mostly occurs in adults and remains throughout life. Long term high-dose anti-thyroid drugs are not recommended after the person becomes euthyroid. Instead, radio-active iodine ablation is recommended. Increased thyroid hormone causes left ventricular thickening that results in an increased risk of cardiac death and other cardiac problems. Eye problems usually improve after proper treatment.

Hyperthyroidism can result from several different causes that are listed below [1].

• Graves disease: It has an autoimmune etiology and is characterized by the presence of auto-antibodies that are capable of stimulating the thyroid gland.
• Toxic multinodular goiter: 60% of the cases of toxic multinodular goiter are caused by defects in the TSH (thyroid stimulating hormone) receptor gene. In 40% of the cases, the cause is unknown.
• Toxic adenoma: Toxic adenoma of the thyroid gland is caused by a point mutation in the TSH (thyroid stimulating hormone) receptor gene.
• Thyroiditis: Different types of thyroiditis have their own etiologies. Hashimoto's thyroiditis has an autoimmune basis whereas De Quervian thyroiditis has a genetic predisposition in specific human leukocyte antigens (HLAs). Suppurative thyroiditis is caused by infections. Drugs such as lithium, amiodarone and interferon-alpha can also cause the development of thyroiditis.

In the United States, the most commonly occurring form of hyperthyroidism is Grave’s disease. It constitutes around 60 to 80% of the total cases. The peak occurrence is in people with ages 20 to 40.

In iodine-deficient areas, the most common type is toxic multi-nodular goiter, comprising up to 15 to 20% of total cases. It typically presents in people older than 50 years of age.

Thyroid hormone secretion is controlled by a complex feed-back mechanism which involves stimulatory and inhibitory factors. The hypothalamus releases thyrotropin-releasing hormone (TRH) which stimulates the pituitary gland to release thyroid stimulating hormone (TSH). Thyroid stimulating hormone in turn causes the release of T3 and T4 from the thyroid gland. Increased levels of T3 and T4 decrease the production of TSH by negative feed-back mechanism.

Any pathology involving the pituitary gland, thyroid or in the periphery leading to increased levels of circulating thyroid hormone results in thyrotoxicosis. Regardless of where the pathology lies, the result is an increase in the transcription of the cellular proteins which then leads to the increased basal metabolic rate [2].

There are no current guidelines on the prevention of hyperthyroidism. Hyperthyroidism caused by Grave’s disease cannot be prevented as it is genetically mediated. However, people residing in iodine deficient areas must introduce iodine in their diets to prevent the occurrence of toxic multi-nodular goiter which is most likely to occur in such areas. This might greatly affect the over-all incidence of hyperthyroidism in these areas.

Also, people with a positive family history of hyperthyroidism or those residing in iodine deficient areas should get themselves periodically checked up for early diagnosis and treatment.

Hyperthyroidism is a term reserved for disorders that result in the overproduction of the thyroid hormone by the thyroid gland. Thyrotoxicosis is a term used to describe a state of thyroid hormone excess resulting from any source. The most common cause of thyroid hormone excess is Graves disease. Toxic multinodular goiter is the second most common cause.

Hyperthyroidism refers to the condition in which the levels of thyroid hormone in the body are high. This leads to a wide range of symptoms including weight loss, increased appetite, increased sweating, intolerance to heat, anxiety and irritability. Hyperthyroidism can be treated by drugs, surgery or radiation.

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3. Chen JL CH, Tseng YJ, Chu WC. Hyperthyroidism is characterized by both increased sympathetic and decreased vagal modulation of heart rate: evidence from spectral analysis of heart rate variability. Clin Endocrinol (Oxf). 2006;64(6):611-616.
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8. Snyder S, Govednik C, Lairmore T, Jiang DS, Song J. Total thyroidectomy as primary definitive treatment for Graves' hyperthyroidism. The American surgeon. Dec 2013;79(12):1283-1288.
9. Boger MS, Perrier ND. Advantages and disadvantages of surgical therapy and optimal extent of thyroidectomy for the treatment of hyperthyroidism. The Surgical clinics of North America. Jun 2004;84(3):849-874.
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