Thyroid Nodules

Overview

Definition

• A disordered growth of thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy cells ( hyperplastic Hyperplastic Colon Polyps or neoplastic) that form a lump or a mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast
• May occur as:
  • Discrete nodule Nodule Chalazion: single or multiple masses in a normal-sized thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy gland 
  • Multinodular goiter Multinodular goiter An enlarged thyroid gland containing multiple nodules (thyroid nodule), usually resulting from recurrent thyroid hyperplasia and involution over many years to produce the irregular enlargement. Multinodular goiters may be nontoxic or may induce thyrotoxicosis. Goiter: Multiple nodules replace the parenchyma and cause thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy enlargement.

Epidemiology

• In the United States, palpable nodules occur in 4%–7% of all adults.
• Incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency increases with age.
• Affects women more than men
• Nature of thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy nodules: 
  • Benign Benign Fibroadenoma > malignant nodules (10:1)
  • Thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy cancer more common in nodules ≥ 2 cm

Risk factors

• Risk factors for thyroid nodules:
  • Smoking and alcohol drinking
  • Obesity and metabolic syndrome
  • Uterine fibroids
  • Elevated insulin-like growth factor (IGF)-1 levels
• Risk factors for malignant nodules:
  • Male gender
  • Young age (< 30 years old)
  • History of radiation to the head or neck
  • Family history of thyroid cancer
  • Familial adenomatous polyposis (FAP) or other associated syndromes
  • Firm, solid, and/or “cold” nodule Nodule Chalazion

Etiology and Pathogenesis

Etiology

• Benign Benign Fibroadenoma:
  • Sporadic Sporadic Selective IgA Deficiency multinodular goiter Multinodular goiter An enlarged thyroid gland containing multiple nodules (thyroid nodule), usually resulting from recurrent thyroid hyperplasia and involution over many years to produce the irregular enlargement. Multinodular goiters may be nontoxic or may induce thyrotoxicosis. Goiter
  • Follicular adenoma: 
    • Discrete solitary mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast developed from follicle epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium: Histology
    • Can become autonomous secreting thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy hormone ( toxic adenoma Toxic Adenoma Thyrotoxicosis and Hyperthyroidism)
  • Thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change: fluid-filled nodules
  • Hurthle cell adenoma
  • Hashimoto’s thyroiditis Thyroiditis Thyroiditis is a catchall term used to describe a variety of conditions that have inflammation of the thyroid gland in common. It includes pathologies that cause an acute illness with severe thyroid pain (e.g., subacute thyroiditis and infectious thyroiditis) as well as conditions in which there is no clinically evident inflammation and the manifestations primarily reflect thyroid dysfunction or a goiter (e.g., painless thyroiditis and fibrous Riedel’s thyroiditis). Thyroiditis
• Malignant:
  • Papillary carcinoma
  • Follicular carcinoma
  • Medullary carcinoma
  • Anaplastic carcinoma
  • Primary thyroid lymphoma Thyroid Lymphoma Thyroid Cancer
  • Metastasis Metastasis The transfer of a neoplasm from one organ or part of the body to another remote from the primary site. Grading, Staging, and Metastasis from other sites

Pathogenesis

• Nodular growth affected by: 
  • Underlying condition (e.g., iodine Iodine A nonmetallic element of the halogen group that is represented by the atomic symbol I, atomic number 53, and atomic weight of 126. 90. It is a nutritionally essential element, especially important in thyroid hormone synthesis. In solution, it has anti-infective properties and is used topically. Thyroid Hormones deficiency, Hashimoto’s thyroiditis Thyroiditis Thyroiditis is a catchall term used to describe a variety of conditions that have inflammation of the thyroid gland in common. It includes pathologies that cause an acute illness with severe thyroid pain (e.g., subacute thyroiditis and infectious thyroiditis) as well as conditions in which there is no clinically evident inflammation and the manifestations primarily reflect thyroid dysfunction or a goiter (e.g., painless thyroiditis and fibrous Riedel’s thyroiditis). Thyroiditis)
  • Varying growth potentials and response to trophic hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types by follicle cells
  • Acquired mutations (e.g., in thyroid-stimulating hormone Thyroid-stimulating hormone A glycoprotein hormone secreted by the adenohypophysis. Thyrotropin stimulates thyroid gland by increasing the iodide transport, synthesis and release of thyroid hormones (thyroxine and triiodothyronine). Thyroid Hormones (TSH) signaling pathway)
  • Recurrent growth leading to follicle rupture and scarring Scarring Inflammation (predisposition to nodularities)
• Thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy carcinoma:
  • Majority arise from thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy follicle epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium: Histology
  • Development affected by:
    • Driver mutations (such as those involving the receptor Receptor Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell. Receptors tyrosine Tyrosine A non-essential amino acid. In animals it is synthesized from phenylalanine. It is also the precursor of epinephrine; thyroid hormones; and melanin. Synthesis of Nonessential Amino Acids kinase pathway) 
    • Environment (especially ionizing radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma)

Clinical Presentation

Signs and symptoms

• Thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy nodules can present as a lump and be found by the patient or the clinician Clinician A physician, nurse practitioner, physician assistant, or another health professional who is directly involved in patient care and has a professional relationship with patients. Clinician–Patient Relationship on physical exam.
• Suspicious features on history and exam:
  • Fixed hard mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast
  • + Cervical lymph nodes Lymph Nodes They are oval or bean shaped bodies (1 – 30 mm in diameter) located along the lymphatic system. Lymphatic Drainage System: Anatomy
  • Symptoms of obstruction (e.g., dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea, wheezing Wheezing Wheezing is an abnormal breath sound characterized by a whistling noise that can be relatively high-pitched and shrill (more common) or coarse. Wheezing is produced by the movement of air through narrowed or compressed small (intrathoracic) airways. Wheezing, dysphagia Dysphagia Dysphagia is the subjective sensation of difficulty swallowing. Symptoms can range from a complete inability to swallow, to the sensation of solids or liquids becoming “stuck.” Dysphagia is classified as either oropharyngeal or esophageal, with esophageal dysphagia having 2 sub-types: functional and mechanical. Dysphagia)
  • Vocal cord paralysis
  • Rapid growth

Incidental finding

• Thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy nodules also present as an incidental finding on radiologic tests obtained for different purposes:
  • Carotid ultrasound
  • Neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess or chest CT
  • PET PET An imaging technique that combines a positron-emission tomography (PET) scanner and a ct X ray scanner. This establishes a precise anatomic localization in the same session. Nuclear Imaging
• No symptoms or observable lesion by exam (but the finding is significant as thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy cancer needs to be ruled out)

Diagnosis

Initial tests

• TSH: normal, elevated, or low
• Thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy ultrasound:
  • Determines nodule Nodule Chalazion size and characteristics (including adjacent structures)
  • Benign Benign Fibroadenoma features: purely cystic Cystic Fibrocystic Change, without solid components
  • Suspicious nodule Nodule Chalazion findings:
    • Composition: solid nodule Nodule Chalazion 
    • Echogenicity: hypoechoic Hypoechoic A structure that produces a low-amplitude echo (darker grays) Ultrasound (Sonography)
    • Shape: more tall than wide
    • Echogenic foci: microcalcifications or rim calcifications with extrusion of soft tissue Soft Tissue Soft Tissue Abscess
    • Margin: irregular borders and/or extrathyroidal extension Extension Examination of the Upper Limbs
  • Other suspicious ultrasound findings:
    • Subcapsular location adjacent to recurrent laryngeal nerve or trachea Trachea The trachea is a tubular structure that forms part of the lower respiratory tract. The trachea is continuous superiorly with the larynx and inferiorly becomes the bronchial tree within the lungs. The trachea consists of a support frame of semicircular, or C-shaped, rings made out of hyaline cartilage and reinforced by collagenous connective tissue. Trachea: Anatomy
    • Abnormal cervical lymph nodes Lymph Nodes They are oval or bean shaped bodies (1 – 30 mm in diameter) located along the lymphatic system. Lymphatic Drainage System: Anatomy
    • Central vascularity
    • Documented growth

Subsequent approach

Based on TSH and ultrasound findings:

• Low TSH:
  • Consistent with hyperthyroidism Hyperthyroidism Hypersecretion of thyroid hormones from the thyroid gland. Elevated levels of thyroid hormones increase basal metabolic rate. Thyrotoxicosis and Hyperthyroidism; requires radioactive iodine Radioactive iodine Unstable isotopes of iodine that decay or disintegrate emitting radiation. I atoms with atomic weights 117-139, except I 127, are radioactive iodine isotopes. Antithyroid Drugs (RAI) uptake scan or thyroid scan Thyroid Scan Nuclear Imaging
  • RAI uptake scan reports the following:
    • Functioning nodule Nodule Chalazion (“hot” or iodine Iodine A nonmetallic element of the halogen group that is represented by the atomic symbol I, atomic number 53, and atomic weight of 126. 90. It is a nutritionally essential element, especially important in thyroid hormone synthesis. In solution, it has anti-infective properties and is used topically. Thyroid Hormones uptake more than surrounding tissue)
    • Nonfunctioning nodule Nodule Chalazion (“cold” or iodine Iodine A nonmetallic element of the halogen group that is represented by the atomic symbol I, atomic number 53, and atomic weight of 126. 90. It is a nutritionally essential element, especially important in thyroid hormone synthesis. In solution, it has anti-infective properties and is used topically. Thyroid Hormones uptake less than surrounding tissue)
    • Indeterminate nodule Nodule Chalazion
  • Approach:
    • Hot nodule Nodule Chalazion (likely benign Benign Fibroadenoma): Evaluate and treat hyperthyroidism Hyperthyroidism Hypersecretion of thyroid hormones from the thyroid gland. Elevated levels of thyroid hormones increase basal metabolic rate. Thyrotoxicosis and Hyperthyroidism.
    • Cold nodule Nodule Chalazion: Consider fine-needle aspiration biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma (FNAB) depending on ultrasound findings, size, and risk factors.
    • Indeterminate: Consider FNAB depending on ultrasound findings, size, and risk factors.
• Normal/elevated TSH:
  • With benign Benign Fibroadenoma ultrasound findings: Monitor, evaluate, and treat hypothyroidism Hypothyroidism Hypothyroidism is a condition characterized by a deficiency of thyroid hormones. Iodine deficiency is the most common cause worldwide, but Hashimoto’s disease (autoimmune thyroiditis) is the leading cause in non-iodine-deficient regions. Hypothyroidism.
  • With suspicious ultrasound findings: Consider FNAB depending on size and risk factors.

Biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma

FNAB indicated in:

• ≥ 1 cm nodule Nodule Chalazion and:
  • Elevated/normal TSH + suspicious ultrasound findings
  • Low TSH + suspicious ultrasound findings + cold or indeterminate nodule Nodule Chalazion(s)
• Large nodule Nodule Chalazion ≥ 1.5 cm
• Thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy nodule Nodule Chalazion of any size with:
  • Risk factors:
    • Young age
    • Family history Family History Adult Health Maintenance of thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy cancer
    • FAP FAP Familial adenomatous polyposis (FAP) is an autosomal dominant inherited genetic disorder that presents with numerous adenomatous polyps in the colon. Familial adenomatous polyposis is the most common of the polyposis syndromes, which is a group of inherited or acquired conditions characterized by the growth of polyps in the GI tract, associated with other extracolonic features. Familial Adenomatous Polyposis or other associated syndromes
    • History of radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma

Management

Treatment approach

Based on biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma results ( Bethesda system Bethesda system A standardized reporting of results of PAP test, which includes the specimen adequacy, general categorization of findings, and results Cervical Cancer Screening diagnostic categories for reporting thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy cytopathology):

• Bethesda I: 
  • Nondiagnostic (inadequate)
  • Management: Repeat FNAB in 4–6 weeks.
• Bethesda II: 
  • Benign Benign Fibroadenoma
  • Management: periodic ultrasound
• Bethesda III:
  • Atypia Atypia Fibrocystic Change of undetermined significance, or follicular lesion of undetermined significance (indeterminate)
  • Management: Repeat biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma and send for molecular markers.
• Bethesda IV:
  • Follicular neoplasm (indeterminate)
  • Management: Repeat biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma and send for molecular markers.
• Bethesda V:
  • Suspicious for malignancy Malignancy Hemothorax
  • > 50% cancer risk
  • Management: surgery
• Bethesda VI:
  • Malignancy Malignancy Hemothorax
  • Management: surgery

Monitoring and other considerations

• Suspicious nodules < 1 cm: 
  • Ultrasound every 6–12 months (frequency declines depending on stability)
  • Less frequent in low-suspicion nodules
• Simple thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change (no solid components):
  • Fine-needle cystic Cystic Fibrocystic Change aspiration
  • Surgery if cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change are recurrent or if size large enough to be bothersome
• Toxic adenoma Toxic Adenoma Thyrotoxicosis and Hyperthyroidism:
  • Surgery
  • Radioiodine ablation Radioiodine Ablation Thyrotoxicosis and Hyperthyroidism

Clinical Relevance

• Goiter Goiter A goiter is a chronic enlargement of the thyroid gland due to nonneoplastic growth occurring in the setting of hypothyroidism, hyperthyroidism, or euthyroidism. Morphologically, thyroid enlargement can be diffuse (smooth consistency) or nodular (uninodular or multinodular). Goiter: the abnormal enlargement of the thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy gland; occurs in hypothyroidism Hypothyroidism Hypothyroidism is a condition characterized by a deficiency of thyroid hormones. Iodine deficiency is the most common cause worldwide, but Hashimoto’s disease (autoimmune thyroiditis) is the leading cause in non-iodine-deficient regions. Hypothyroidism, hyperthyroidism Hyperthyroidism Hypersecretion of thyroid hormones from the thyroid gland. Elevated levels of thyroid hormones increase basal metabolic rate. Thyrotoxicosis and Hyperthyroidism, or euthyroidism. Presentation can be a diffusely enlarged or multinodular thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy gland. Diagnostic tests Diagnostic tests Diagnostic tests are important aspects in making a diagnosis. Some of the most important epidemiological values of diagnostic tests include sensitivity and specificity, false positives and false negatives, positive and negative predictive values, likelihood ratios, and pre-test and post-test probabilities. Epidemiological Values of Diagnostic Tests include thyroid function tests Thyroid Function Tests Blood tests used to evaluate the functioning of the thyroid gland. Ion Channel Myopathy and thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions. Radiologic imaging helps confirm if concerning features are present. Treatment options include observation, medication, surgery, and radioiodine ablation Radioiodine Ablation Thyrotoxicosis and Hyperthyroidism (depending on findings).
• Thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy cancer: most common cancer in the endocrine system. Malignancy Malignancy Hemothorax arises from the cell type of the gland: thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy follicular cells, calcitonin-producing C cells C cells Calcium Hemostasis and Bone Metabolism, lymphocytes Lymphocytes Lymphocytes are heterogeneous WBCs involved in immune response. Lymphocytes develop from the bone marrow, starting from hematopoietic stem cells (HSCs) and progressing to common lymphoid progenitors (CLPs). B and T lymphocytes and natural killer (NK) cells arise from the lineage. Lymphocytes: Histology, and stromal/vascular elements. Metastasis Metastasis The transfer of a neoplasm from one organ or part of the body to another remote from the primary site. Grading, Staging, and Metastasis from other malignancies can also occur in the thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy gland. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship can present with a growing thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast, thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy asymmetry Asymmetry Examination of the Upper Limbs, or gland enlargement/ swelling Swelling Inflammation. Diagnosis is by biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma. Treatment varies by type and stage, but options include surgery, RAI, targeted therapy Targeted Therapy Targeted therapy exerts antineoplastic activity against cancer cells by interfering with unique properties found in tumors or malignancies. The types of drugs can be small molecules, which are able to enter cells, or monoclonal antibodies, which have targets outside of or on the surface of cells. Targeted and Other Nontraditional Antineoplastic Therapy, and radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma therapy.
• Hypothyroidism Hypothyroidism Hypothyroidism is a condition characterized by a deficiency of thyroid hormones. Iodine deficiency is the most common cause worldwide, but Hashimoto’s disease (autoimmune thyroiditis) is the leading cause in non-iodine-deficient regions. Hypothyroidism: a condition characterized by the deficiency of thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview and Types. Iodine Iodine A nonmetallic element of the halogen group that is represented by the atomic symbol I, atomic number 53, and atomic weight of 126. 90. It is a nutritionally essential element, especially important in thyroid hormone synthesis. In solution, it has anti-infective properties and is used topically. Thyroid Hormones deficiency and Hashimoto’s thyroiditis Thyroiditis Thyroiditis is a catchall term used to describe a variety of conditions that have inflammation of the thyroid gland in common. It includes pathologies that cause an acute illness with severe thyroid pain (e.g., subacute thyroiditis and infectious thyroiditis) as well as conditions in which there is no clinically evident inflammation and the manifestations primarily reflect thyroid dysfunction or a goiter (e.g., painless thyroiditis and fibrous Riedel’s thyroiditis). Thyroiditis are the 2 leading etiologies. Clinical features reflect the effects of slowed organ function and decreased metabolic rate. Lab tests show elevated TSH and a low free thyroxine Thyroxine The major hormone derived from the thyroid gland. Thyroxine is synthesized via the iodination of tyrosines (monoiodotyrosine) and the coupling of iodotyrosines (diiodotyrosine) in the thyroglobulin. Thyroxine is released from thyroglobulin by proteolysis and secreted into the blood. Thyroid Hormones ( T4 T4 The major hormone derived from the thyroid gland. Thyroxine is synthesized via the iodination of tyrosines (monoiodotyrosine) and the coupling of iodotyrosines (diiodotyrosine) in the thyroglobulin. Thyroxine is released from thyroglobulin by proteolysis and secreted into the blood. Thyroxine is peripherally deiodinated to form triiodothyronine which exerts a broad spectrum of stimulatory effects on cell metabolism. Thyroid Hormones). Treatment is with levothyroxine Levothyroxine Thyroid Replacement Therapy.
• Hyperthyroidism Hyperthyroidism Hypersecretion of thyroid hormones from the thyroid gland. Elevated levels of thyroid hormones increase basal metabolic rate. Thyrotoxicosis and Hyperthyroidism: a condition caused by sustained overproduction and release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology of the thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy hormone triiodothyronine Triiodothyronine A T3 thyroid hormone normally synthesized and secreted by the thyroid gland in much smaller quantities than thyroxine (T4). Most T3 is derived from peripheral monodeiodination of T4 at the 5′ position of the outer ring of the iodothyronine nucleus. The hormone finally delivered and used by the tissues is mainly t3. Thyroid Hormones ( T3 T3 A T3 thyroid hormone normally synthesized and secreted by the thyroid gland in much smaller quantities than thyroxine (T4). Most T3 is derived from peripheral monodeiodination of T4 at the 5′ position of the outer ring of the iodothyronine nucleus. The hormone finally delivered and used by the tissues is mainly t3. Thyroid Hormones) and T4 T4 The major hormone derived from the thyroid gland. Thyroxine is synthesized via the iodination of tyrosines (monoiodotyrosine) and the coupling of iodotyrosines (diiodotyrosine) in the thyroglobulin. Thyroxine is released from thyroglobulin by proteolysis and secreted into the blood. Thyroxine is peripherally deiodinated to form triiodothyronine which exerts a broad spectrum of stimulatory effects on cell metabolism. Thyroid Hormones. Graves’ disease is the most common cause of hyperthyroidism Hyperthyroidism Hypersecretion of thyroid hormones from the thyroid gland. Elevated levels of thyroid hormones increase basal metabolic rate. Thyrotoxicosis and Hyperthyroidism. Manifestations are mostly due to the increased metabolic rate and overactivity of the sympathetic nervous system Nervous system The nervous system is a small and complex system that consists of an intricate network of neural cells (or neurons) and even more glial cells (for support and insulation). It is divided according to its anatomical components as well as its functional characteristics. The brain and spinal cord are referred to as the central nervous system, and the branches of nerves from these structures are referred to as the peripheral nervous system. Nervous System: Anatomy, Structure, and Classification. Lab tests show low TSH and elevated free T4 T4 The major hormone derived from the thyroid gland. Thyroxine is synthesized via the iodination of tyrosines (monoiodotyrosine) and the coupling of iodotyrosines (diiodotyrosine) in the thyroglobulin. Thyroxine is released from thyroglobulin by proteolysis and secreted into the blood. Thyroxine is peripherally deiodinated to form triiodothyronine which exerts a broad spectrum of stimulatory effects on cell metabolism. Thyroid Hormones. Treatment depends on the underlying condition.
• Hashimoto’s thyroiditis Thyroiditis Thyroiditis is a catchall term used to describe a variety of conditions that have inflammation of the thyroid gland in common. It includes pathologies that cause an acute illness with severe thyroid pain (e.g., subacute thyroiditis and infectious thyroiditis) as well as conditions in which there is no clinically evident inflammation and the manifestations primarily reflect thyroid dysfunction or a goiter (e.g., painless thyroiditis and fibrous Riedel’s thyroiditis). Thyroiditis: the most common cause of hypothyroidism Hypothyroidism Hypothyroidism is a condition characterized by a deficiency of thyroid hormones. Iodine deficiency is the most common cause worldwide, but Hashimoto’s disease (autoimmune thyroiditis) is the leading cause in non-iodine-deficient regions. Hypothyroidism in iodine-sufficient regions. Hashimoto’s thyroiditis Thyroiditis Thyroiditis is a catchall term used to describe a variety of conditions that have inflammation of the thyroid gland in common. It includes pathologies that cause an acute illness with severe thyroid pain (e.g., subacute thyroiditis and infectious thyroiditis) as well as conditions in which there is no clinically evident inflammation and the manifestations primarily reflect thyroid dysfunction or a goiter (e.g., painless thyroiditis and fibrous Riedel’s thyroiditis). Thyroiditis (also known as chronic lymphocytic thyroiditis Chronic lymphocytic thyroiditis Hashimoto’s thyroiditis, or chronic lymphocytic thyroiditis, is the most common cause of hypothyroidism in iodine-sufficient regions. The condition is an autoimmune disorder leading to destruction of the thyroid cells and thyroid failure. The gradual clinical course of hashimoto’s thyroiditis starts with a transient hyperthyroid state (“hashitoxicosis”) followed by subclinical hypothyroidism. Hashimoto’s Thyroiditis) is an autoimmune disorder Autoimmune Disorder Septic Arthritis leading to the destruction of the thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy cells and to thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy failure. Presentation may be a painless goiter Goiter A goiter is a chronic enlargement of the thyroid gland due to nonneoplastic growth occurring in the setting of hypothyroidism, hyperthyroidism, or euthyroidism. Morphologically, thyroid enlargement can be diffuse (smooth consistency) or nodular (uninodular or multinodular). Goiter. In later stages, the gland is atrophic. Lab tests show elevated TSH, low free T4 T4 The major hormone derived from the thyroid gland. Thyroxine is synthesized via the iodination of tyrosines (monoiodotyrosine) and the coupling of iodotyrosines (diiodotyrosine) in the thyroglobulin. Thyroxine is released from thyroglobulin by proteolysis and secreted into the blood. Thyroxine is peripherally deiodinated to form triiodothyronine which exerts a broad spectrum of stimulatory effects on cell metabolism. Thyroid Hormones, and positive antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions against thyroglobulin Thyroglobulin Thyroid Hormones and thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy peroxidase. Treatment is lifelong thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy replacement therapy.