What are the other Names for this Condition? (Also known as/Synonyms)

• Disorders of the Thyroid Gland
• Thyroid Gland Function Disorders

What are Thyroid Function Disorders? (Definition/Background Information)

• Thyroid Function Disorders may be described as a group of disorders that affect the normal functioning of the thyroid gland. These may be categorized as primary or secondary, depending on whether the thyroid gland is directly involved (primary), or factors extrinsic to the thyroid contribute to its dysfunction (secondary)
• The thyroid gland is a butterfly-shaped gland located in the front of the neck. It is responsible for secreting thyroid hormones (such as thyroxine) that monitor our body temperature, heart rate, blood pressure, and weight
• Thyroxine is responsible for regulating the body's metabolism. It stimulates cells of the body to produce proteins, and also increases the amount of oxygen used by them. It also has a very important role in fetal brain development
• Thyroid Function Disorders result either in an excess production of the thyroid hormone (termed hyperthyroidism) or a deficient production of the hormone (termed hypothyroidism). These conditions result in several symptoms and complications, particularly if they are left undiagnosed and/or untreated. These conditions may be further (broadly) grouped as:
  • Primary hyperthyroidism
  • Secondary hyperthyroidism
  • Primary hypothyroidism
  • Secondary hypothyroidism
• The cause of Thyroid Function Disorders depends on the specific type of the disorder, but may include Hashimoto’s thyroiditis, Graves’ disease, removal of the thyroid gland, pituitary gland dysfunction, TSH-secreting pituitary adenoma, smoking, thyroid gland inflammation, and certain genetic disorders
• The signs and symptoms of Thyroid Function Disorders are dependent upon the specific disorder type. These may include weight gain or loss, heat or cold intolerance, abnormal heartbeat, dry skin, fatigue, and mental health issues. The associated symptoms of the underlying condition causing an abnormal function of the thyroid gland may also be noted
• The treatment of Thyroid Function Disorders may involve addressing the symptoms and treating the underlying cause. A replacement of thyroid hormone is an important part of managing hypothyroidism; or, administering certain anti-thyroid medications for hyperthyroidism
• The prognosis of Thyroid Function Disorders is generally good with appropriate early treatment, despite the requirement of medications for a lifetime in some cases. However, this may vary from case to case, depending on the particular form of the underlying disorder and its severity

Who gets Thyroid Function Disorders? (Age and Sex Distribution)

• Thyroid Function Disorders are fairly common conditions that may affect both children and adults; however, most cases are reported in adults
• A large number of cases are diagnosed in middle-aged and older women
• All racial and ethnic groups are at risk for both hyperthyroidism and hypothyroidism

What are the Risk Factors for Thyroid Function Disorders? (Predisposing Factors)

The risk factors for Thyroid Function Disorders are dependent on the respective risk factors of hyperthyroidism and hypothyroidism.

Risk factors associated with hyperthyroidism include:

• Family history of Grave’s disease
• Age: Onset of Graves’ disease typically occurs between 20-25 years of age
• Smoking
• Gender: Women are at higher risk than men
• Very high or very low iodine intake

Risk factors for hypothyroidism may include:

• Postmenopausal women over the age of 60 years
• Positive family history of thyroid disorders
• Having undergone surgery to remove the thyroid gland either totally or partially, for various other health reasons
• Radiation therapy to the head and neck region
• Recent pregnancy
• Autoimmune disorders such as rheumatoid arthritis or Sjögren’s syndrome
• Use of certain medications
• Nutritional deficiency of iodine

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Thyroid Function Disorders? (Etiology)

Thyroid Function Disorders develop due to an abnormally-functioning thyroid gland, which results in an overproduction or underproduction of the hormone thyroxine; these conditions are respectively termed hyperthyroidism and hypothyroidism.

• The thyroid disorder may arise directly due to a dysfunction of the thyroid gland - when it is termed primary hyperthyroidism or hypothyroidism
• Or, it may be due to other health issues in the body that prevent the thyroid gland from secreting enough hormones - termed secondary hyperthyroidism or hypothyroidism

The cause associated with hyperthyroidism:

• Graves’ disease
• Intake of iodine supplements
• Toxic nodular goiter
• Inflammation of thyroid gland (thyroiditis) due infections, certain medications, or pregnancy
• Carcinoma of the thyroid gland
• Toxic adenoma of thyroid gland (thyroid adenoma)
• Thyroid stimulating hormone secreting pituitary adenoma
• Gestational thyrotoxicosis
• Human chorionic gonadotropin (hCG) producing tumor

The cause associated with hypothyroidism:

• Presence of autoimmune disorders such as Hashimoto’s thyroiditis (most common cause) and atrophic thyroiditis
• Partial or complete thyroidectomy
• Congenital hypothyroidism, due to fetal development issues
• Treatment with radioactive iodine (I-131)
• Inflammation of thyroid gland due infections, certain medications, or pregnancy
• Pituitary gland abnormalities
• Excess or deficient iodine in the body
• Other conditions that affect the thyroid gland and disrupt its normal function such as amyloidosis, sarcoidosis, and hemochromatosis

What are the Signs and Symptoms of Thyroid Function Disorders?

The signs and symptoms of Thyroid Function Disorders may vary from one individual to another, depending on the specific underlying condition causing the dysfunction. The rate of development of the signs and symptoms may be slow in many individuals, resulting in a delayed diagnosis of the condition.

The signs and symptoms of hyperthyroidism may include:

• Rapid weight loss
• Fatigue
• Irritability, paranoia
• Heat intolerance
• Diarrhea
• Tremors
• Thinning of skin
• Red or protruding eyes, swelling or inflammation around the eyes
• Irregular heartbeat, sweating, and palpitations
• High blood pressure

The signs and symptoms of hypothyroidism may include:

• Feeling of tiredness
• Weight gain
• Difficulty in tolerating cold conditions
• Muscle aches and joint pain
• Irregular and heavy menstrual periods
• Constipation or hard stools
• Reduced sweating
• Dryness of skin
• Goiter or enlarged thyroid gland
• Hoarse voice
• Mental health issues such as depression and absentmindedness
• Abnormally slowed heart rate (slow pulse)
• Shortness of breath

Additionally, the signs and symptoms of any associated condition (causing secondary forms of hyperthyroidism or hypothyroidism) may be noted.

How are Thyroid Function Disorders Diagnosed?

The diagnosis of Thyroid Function Disorders may involve the following tests and procedures:

• Complete evaluation of medical history along with a thorough physical exam
• Assessment of one’s signs and symptoms
• Diagnostic tests that may include:
  • TSH blood test
  • T3 and T4 blood test
  • TRH (thyrotropin releasing hormone) blood test
  • Creatine kinase blood test
  • Lipid profile
  • Radioactive iodine uptake test
  • Ultrasound scan of the thyroid gland
  • CT scan of head or MRI of brain to detect tumors in the pituitary gland
• Thyroid gland biopsy, if necessary
• Tests to diagnose an underlying condition may be necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Thyroid Function Disorders?

The complications of Thyroid Function Disorders depend on the type and severity of condition causing the same.

The complications associated with hyperthyroidism include:

• Osteoporosis: A condition causing brittle bones
• Heart disorders such as abnormal heart rhythm and heart failure
• Thyroid storm/crisis, which is a medical emergency

The complications associated with hypothyroidism include:

• Myxedema coma: A medical emergency caused by severely deficient levels of thyroid hormones
• Pregnant women are at an increased risk for miscarriage
• Infertility
• Fetal death
• Physical and mental development issues in newborns
• Carpal tunnel syndrome
• Fluid accumulation in various organs such as the lungs and heart
• Side effects of thyroxine treatment, including increased risk for hyperthyroidism (due to over-treatment)

Complications that may arise from an underlying or associated health condition may be additionally noted.

How are Thyroid Function Disorders Treated?

The treatment of Thyroid Function Disorders depend on whether it is caused by an overactive or underactive thyroid gland, and on the conditions associated with the disorder.

The treatment of hyperthyroidism may include:

• Symptomatic treatment through the administration of anti-thyroid medications, such as propylthiouracil and methimazole, and beta blockers
• Radioactive iodine to stop excess production of the thyroid hormones
• Surgery to remove the thyroid gland

The treatment of hypothyroidism may include:

• Hormone replacement: Administration of thyroid hormone medications (thyroxine) to restore T3, T4, and TSH levels to normalcy
• Symptomatic treatment through medications; bringing about certain lifestyle changes (food, exercise, and stress control)
• Considering early adequate treatment of autoimmune disease, genetic conditions, and infections causing hypothyroidism
• A careful and periodic monitoring of pregnancy (including close fetal monitoring) is advised and recommended

Undertaking treatment of the underlying cause of secondary hyperthyroidism or hypothyroidism forms an important part of addressing the condition.

Regular medical screening at periodic intervals with tests and physical examinations are necessary, especially for pregnant women.

How can Thyroid Function Disorders be Prevented?

The prevention of Thyroid Function Disorders depends on preventing/avoiding the specific risk factors and cause of hyperthyroidism or hypothyroidism. In many cases, it may not be possible to prevent the condition.

However, considering certain factors may help lower one’s risk for the same: 

• Knowledge about one’s family history is helpful in assessing future risks for the condition
• Individuals at risk should refrain from smoking and regularly follow-up with a physician to ensure early detection
• Drugs that cause the condition may be discontinued or alternative medication prescribed
• Avoiding nutritional (iodine) deficiencies through proper dietary control

Early detection and prompt treatment of causative conditions may lower one’s risk for hyperthyroidism or hypothyroidism.

What is the Prognosis of Thyroid Function Disorders? (Outcomes/Resolutions)

The prognosis of Thyroid Function Disorders depends on the underlying cause, underlying risk factors, severity of the signs and symptoms, and the response of each individual to treatment measures. In general, the prognosis is good with appropriate treatment.

• Some individuals may either require lifelong medications to keep the symptoms under control; also, a periodic screening of T3, T4, and TSH levels are recommended
• The prognosis of secondary hyperthyroidism or hypothyroidism depends on the severity of the underlying cause associated with it

Additional and Relevant Useful Information for Thyroid Function Disorders:

The following article links will help you understand thyroid-stimulating hormone (TSH), total T3, and total T4 laboratory tests:

http://www.dovemed.com/common-procedures/procedures-laboratory/thyroid-stimulating-hormone-tsh-test/

http://www.dovemed.com/common-procedures/procedures-laboratory/total-t3-blood-test/

http://www.dovemed.com/common-procedures/procedures-laboratory/total-t4-blood-test/