Overview
The thyroid gland is part of the intricate glandular network that coordinates our bodily functions. The thyroid gland is the butterfly-shaped gland in the neck that is responsible for controlling our metabolism. Imbalances in the secretion of thyroid hormone can affect vital functions. T3 (Triiodothyronine) and T4 (Tetraiodothyronine) are thyroid-specific hormones that regulate metabolism.
The pituitary gland maintains the amount of these hormones by secreting Thyroid Stimulating Hormone (TSH). Thyroid homeostasis is maintained by this feedback mechanism between two glands. Thyroid disorders can be broadly categorized based on the amount of secretion.
Excess thyroid hormone causes hyperthyroidism and an abnormal increase in metabolism, increased heart rate, loss of weight, and decreased secretion causing hypothyroidism, which can lead to decreased energy, weight gain, fatigue, and cold intolerance.
Associated Anatomy:
Trachea, Larynx
Alternate Names
Graves’s Disease, Hashimoto’s Thyroiditis, Goiter
Thyroid Symptoms
Symptoms of hyperthyroidism:
- Excessive sweating (hyperhidrosis)
- irregular heartbeat, rapid heartbeat
- Fatigue
- Insomnia
- Heat intolerance
- Trembling hands
- Goiter (Enlargement in the neck)
- Irritability
- Anxiety
- Frequent defecation
Symptoms of hypothyroidism are:
- Thinning hair
- Fatigue
- Depression
- Menorrhagia
- Muscle weakness and joint pain
- Dry skin
- Puffy face (moon face)
- Weight gain
- Constipation
- Myxoedema (fluid retention in tissues) can cause pitting edema
- Cold intolerance
- Impaired memory
- Inattentiveness
Thyroid Causes
Thyroid diseases can be attributed to genetic and environmental factors. They are categorized broadly as hyperthyroidism and hypothyroidism.
Hyperthyroidism: increase in the amount of thyroid hormone due to:
- Toxic goiter or Grave’s disease
- Multi-nodular goiter
- Iodine excess
- Thyroiditis
- Pituitary gland tumor causing excessive TSH secretion.
Hypothyroidism: Decrease in the amount of thyroid hormone due to:
- Autoimmune conditions
- Iodine deficiency
- Non-functioning thyroid gland
- Radiation therapy
- Surgical removal of the gland
- Medications suppressing thyroid gland
Thyroid Types
Thyroiditis: Inflammation of the thyroid from infections or autoimmune conditions—it can be asymptomatic or painful.
Grave’s Disease: Excessive thyroid hormone production due to an overactive gland.
Hashimoto’s Disease: Decreased production of thyroid hormone caused due to damage to the thyroid as a result of autoimmune disease.
Thyroid Cancer: Cancerous mass in the gland causing increased hormone secretion. It is a treatable condition with the help of radiation and surgery.
Thyroid Nodule: Abnormal nodular mass in the thyroid gland leads to hormone overproduction.
Thyroid Storm: Abnormally high levels of thyroid hormone causing severe complications.
Thyroid Diagnosis
Accurate diagnoses can be made based on testing and imaging results. T3, T4, and TSH levels are crucial parameters for gauging thyroid dysfunctions. Deviation from the normal levels can be suggestive of underlying disease.
Below are the normal levels of hormones.
T3 (Triiodothyronine) |
100-200 ng/dL |
T4 (Tetraiodothyronine) |
5.0-12.0 μg/dL |
T4 (Tetraiodothyronine) |
0.4-4.0 mIU/L |
Blood Tests:
- Anti-TPO antibodies
- Thyroid stimulation hormone
- T3 (Tetraiodothyronine)
- T4 (Tetraiodothyronine)
- Free T4 (Tetraiodothyronine) and T3 (Triiodothyronine)
- Calcitonin
- Thyroglobulin
Imaging:
- Ultrasound for detecting abnormal tissue.
- Thyroid scan with the help of fluorescent die.
- CT, MRI, and PET scan in case of metastasized thyroid cancer.
Other:
- Physical exam including manual examination of the gland to check for lumps or irregularities.
- A thyroid biopsy is done with a needle to retrieve a small tissue sample.
Thyroid Diseases Preventions
Thyroid dysfunction, if unchecked, can lead to a spectrum of problems. In case of genetic predisposition, it is suggested to schedule regular check-ups and testing. While hypothyroidism can be prevented through iodized salt intake, hyperthyroidism is not preventable, and certain lifestyles can set off an autoimmune disease-causing increased thyroid hormone levels. Maintaining a healthy lifestyle and preventing complications with timely diagnosis, identifying symptoms, and medication are effective preventive measures.
Thyroid Treatments Options
In individuals with thyroid diseases, lifestyle changes form a major part of thyroid treatment for maintaining normal function. Adapting to an active lifestyle alongside a steady nutritious diet helps in the long run.
- Surgical interventions include thyroidectomy, in which a part or complete thyroid gland is removed.
- Medications such as anti-thyroid drugs or beta-blockers control the symptoms. Thyroid replacement drugs in case of hypothyroidism.
- Radioactive iodine injection destroys the overactive glandular cells.
- An external radiation beam is targeted at the gland to kill cancerous cells.
- Recombinant human TSH is injected, which stimulates the gland, and cancer can be seen more clearly on imaging.
Risk Factors for Thyroid Disease
- Various risk factors for thyroid dysfunctions are:
- Hereditary -Family history of Thyroid diseases
- Pre-existing autoimmune conditions
- Past trauma to the thyroid gland
- Pregnancy
- Smoking
- Use of iodine-based contrasts
- Past medications with excess lithium and iodine
- Stress
- Increasing age (especially in females)
Complications Related to Thyroid Diseases
Thyroid dysfunctions can lead to several complications in the long run.
- Cardiovascular issues
- Osteoporosis
- Fever
- Delirium
- Blurred vision or loss of vision
- Brittle bones
- Redness of the skin
- Miscarriages or premature birth
- Myxedema
- Infertility
- Birth defects
Prognosis
The prognosis for thyroid diseases is good. And it can be managed successfully with medications and lifestyle changes. Consult with a medical professional for thyroid treatment options and schedule regular visits to review the symptoms.
Natural Progression
If left untreated and no lifestyle modifications are made, the symptoms related to thyroid diseases worsen and lead to obesity, heart attack, infertility, and depression.
Pathophysiology
Thyroid diseases are caused due to abnormal levels of increase or decrease in hormone secretion. It can also be caused due to increase or decrease in Thyroid Stimulating Hormones secreted by the pituitary gland.