Hyperthyroidism

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Definition/Description

Hyperthyroidism, often referred to as thyrotoxicosis, is a disorder that occurs when the thyroid gland secretes excessive amounts of thyroxine (T4) and/or triiodothyronine (T3). T4 and T3 are thyroid hormones that are responsible for regulating a person’s basal metabolism and increasing metabolic activity and protein synthesis (PATH). An excess amount of thyroid hormone leads to an increased metabolic rate, which affects almost every system in the body (DD).

Prevalence

Hyperthyroidism is four times more prevalent in females. Women between the ages of 20-40 are even more prone to developing this disease. Graves disease is the most common type of hyperthyroidism, comprising approximately 85% of cases (Path).

Characteristics/Clinical Presentation

People with hyperthyroidism may present with a variety of symptoms depending on the person’s age, the quantity of excess hormones, the period of time the person has been sick, and the presence of a comorbid condition (AAFP). It is often difficult to detect the disease in older adults because they do not present with many of the typical signs and symptoms. Instead, they will often appear to have other illnesses, such as heart disease, depression, or dementia. Older people also tend to act more apathetic than hyperactive, and are more likely to have cardiovascular problems (PATH). In addition to tachycardia, fatigue and weight loss which are commonly seen in adults over 70, people younger than age 50 will also typically display hyperactive reflexes, increased perspiration, heat intolerance, fatigue, tremor, nervousness, polydipsia, weakness, increased appetite, dyspnea, and weight loss despite normal food intake (DD). Women may also notice a change in their menstrual cycles (Mayo). Emotions can also become affected, causing a person’s moods to cycle between a euphoric state and acting hyperactive to feeling depressed and acting delusional (Path).

In addition to the signs and symptoms previously mentions, two key features of people with Graves’ disease are an enlarged thyroid gland (goiter) and exophthalmos which occurs in approximately 50% of people with the disease (AAFP). Exophthalmos is an abnormal protrusion of the eyes which occurs as tissue and muscles behind the eye become inflamed causing the eyelids to retract (DD). Graves’ dermopathy, reddening and swelling of the skin, is also a sign of Graves’ disease, but is very rare. If seen it will commonly appear on the shins and the dorsum of the foot (Mayo).

In a patient with untreated, incorrectly treated, or undiagnosed hyperthyroidism, a stressful situation, such as surgery, labor, MI, pulmonary embolism, or medication overdose may cause an acute episode of thyroid over activity to occur. This event is known as thyroid storm, a rare complication of hyperthyroidism that is characterized by a high fever, tachycardia, dehydration, delirium, and extreme irritability (Path).

Chronic periarthritis and calcific tendinitis are also associated with hyperthyroidism. They both tend to occur in the shoulder, causing limitations in a person’s ROM, which may progress and lead to adhesive capsulitis. These conditions are both common in people who have endocrine disease. Once the underlying hyperthyroidism is treated, chronic periarthritis will usually resolve as well.

Approximately 70% of people with hyperthyroidism will develop weakness in the proximal muscles, such as the hips, which is accompanied by myopathy. Muscle strength generally returns after two months of treatment. Muscle atrophy will take a longer period of time to restore (DD).

Associated Co-morbidities

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Medications

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Diagnostic Tests/Lab Tests/Lab Values

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Causes

The most common cause of hyperthyroidism is Grave’s disease, which accounts for approximately 85 percent of cases. It is an autoimmune disease in which an antibody that works against the thyroid stimulating hormone (TSH) receptor causes an increase in T4 production (AAFP/Path). Other causes of Hyperthyroidism include:

• Toxic multinodular goiter:  Accounts for approximately 5% of cases in the U.S. It is much more common in countries where iodine deficiency is more prevalent. This condition usually occurs in people over age 40 that have had a goiter for an extended period of time.
• Toxic adenoma:  This condition also occurs rarely in the U.S. It is common in the younger population in iodine-deficient countries.
• Thyroiditis:

          Subacute thyroiditis often occurs following a viral illness. Symptoms usually resolve in eight months, and may occur repeatedly in some people. 

          Lymphocyctic and Postpartum are both types of thyroiditis that last for a short duration of time. Postpartum thyroiditis occurs in around 5-10% of women in the first 3-6 weeks after delivery. It is common for a person to experience hypothyroidism briefly before the condition resolves.

• Treatment-induced:  Iodine, Amiodarone, Thyroid hormone
• Tumors

(AAFP).

Systemic Involvement

Central Nervous System

• Tremor
• Irritable
• Labile emotions
• Muscle weakness and myopathy
• Increased DTR
• Increased motor activity
• Fatigue

Cardiovascular

• Tachycardia
• Palpitations
• Breathlessness
• Increased respiratory rate
• Low blood pressure
• Heart failure

Integumentary

• Chronic periarthritis
• Dilated capillaries
• Heat intolerance
• Brittle hair
• Onycholysis
• Hyperpigmentation

Ocular

• Exophthalmos
• light sensitivity
• vision loss
• weak extraocular muscles

Gastrointestinal

• Increased metabolism/weight loss
• Increased peristalsis
• Diarrhea
• Dysphagia

Genitourinary

• Polyuria
• Amenorrhea
• Female infertility
• Miscarriage

(DD)

Medical Management (current best evidence)

The approach taken to treat this disease depends on the cause and severity of the patient’s symptoms. The three main approaches to therapy are: antithyroid medication, radioactive iodine, and surgery (Medline).

Physical Therapy Management (current best evidence)

Preferred Practice Patterns:

4C:  Impaired muscle performance

4D:  Impaired joint mobility, motor function, muscle performance, and ROM associated with connective tissue dysfunction

4E:  Impaired joint mobility, motor function, muscle performance, and ROM associated with localized inflammation

6B:  Impaired aerobic capacity/endurance assoiciated with deconditioning

Alternative/Holistic Management (current best evidence)

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Differential Diagnosis

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Case Reports

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Resources

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Recent Related Research (from Pubmed)

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References

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