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Thyroid Disease. Hajinasrollah Esmaeil, M.D Loghman Medical Center Shahid Beheshti University. KERMAN IRAN. History. HistoryGreek thyreoeides, shield-shaped Goiters (from the Latin gllttllr, throat), defined as an enlargement of the thyroid, have been recognized since 2700 B.c.
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ThyroidDisease Hajinasrollah Esmaeil, M.D Loghman Medical Center Shahid Beheshti University
History • HistoryGreek thyreoeides, shield-shaped • Goiters (from the Latin gllttllr, throat), defined as an enlargement of the thyroid, have been recognized since 2700 B.c. • In 1619, Hieronymus Fabricius ab Aquapendente recognized that goiters arose from the thyroid gland,
History • Roger Frugardi in 1170. • Emil Theodor Kocher (1841-1917) and Theodor Billroth (1829-1894), • William Halsted was the first surgeon to suggest that outcomes were dependent upon operative technique.
Lymphatic System The thyroid gland is endowed with an extensive network of lymphatics. Intraglandular lymphatic vessels connect both thyroid lobes through the isthmus and also drain to peri thyroidal structures and
THYROID HISTOLOGYMicroscopically ---20 to 40 follicles. 3 x 106 follicles cuboidal epithelial cells ---contains a central store of colloid secreted from the epithelial cells under the influence of the pituitary hormone, TSH. ---The second group of thyroid secretory cells is the C cells or parafollicular cells, which contain and secrete the hormone calcitonin
Developmental Abnormalities 1-Thyroglossal Duct Cyst and Sinus: Are the most commonly encountered congenital cervical anomalies. During the fifth week of gestation, the thyroglossal duct lumen starts to obliterate and the duct disappears by the eighth week of gestation 80% are found in juxtaposition to the hyoid bone Are lined by pseudostratified ciliated columnar epithelium and squamous epithelium, with heterotopic thyroid tissue present in 20% of cases.
2-Thyroglossal Duct Cyst and Sinus: • 1- to 2-cm, smooth, well-defined midline neck mass that moves upward with protrusion of the tongue • Approximately 1% of thyroglossal duct cysts are found to contain cancer, which is usually papillary (85%). • Squamous, Hürthle cell, and anaplastic cancers also have been reported but are rare. Medullary thyroid cancers (MTCs) are, however, not found in thyroglossal duct cysts
Lingual Thyroid *Represents a failure of the median thyroid anlage to descend normally. *Intervention becomes necessary for obstructive symptoms such as choking, dysphagia, airway obstruction, or hemorrhage. *Many of these patients develop hypothyroidism. *Medical treatment options include administration of exogenous thyroid hormone and radioactive iodine (RAI) ablation followed by hormone replacement.
Ectopic Thyroid *May be found anywhere in the central neck compartment, including the esophagus, trachea, and anterior mediastinum. *Thyroid tissue situated lateral to the carotid sheath and jugular vein, previously termed lateral aberrant thyroid, almost always represents metastatic thyroid cancer in lymph nodes, and not remnants of the lateral anlage.
Pyramidal Lobe • Normally the thyroglossal duct atrophies, although it may remain as a fibrous band. In about 50% of individuals, the distal end that connects to the thyroid persists as a pyramidal lobe • Pyramidal lobe is not palpable, but in disorders resulting in thyroid hypertrophy (e.g., Graves' disease, diffuse nodular goiter, or lymphocytic thyroiditis), the pyramidal lobe usually is enlarged and palpable.
Evaluation of Patients with Thyroid Disease 1-The ultrasensitive TSH : *The most sensitive and specific test for the diagnosis of hyper- and hypothyroidism and for optimizing T4 therapy. 2-Total T4 , T3 levels ↑ Total T4 levels: *Hyperthyroid patients *Elevated Tg levels secondary to pregnancy, estrogen/progesterone use, or congenital diseases.
Evaluation of Patients with Thyroid Disease ↓Total T4 levels : *Hypothyroidism *Decreased Tg levels due to anabolic steroid use and protein-losing disorders like nephrotic syndrome. Individuals with these latter disorders may be euthyroid if their free T4 levels are normal. *Measurement of total T3levels is important in clinically hyperthyroid patients with normal T4 levels, who may have T3 thyrotoxicosis. Total T3 levels often are increased in early hypothyroidism.
Evaluation of Patients with Thyroid Disease 3- Thyrotropin-Releasing Hormone Evaluate pituitary TSH secretory function. 4- Thyroid Antibodies Anti-Tg, Antimicrosomal, anti-TPO ; Thyroid-stimulating immunoglobulin (TSI) ↑ Thyroid Antibodies -80% of patients with Hashimoto's thyroiditis -Graves' disease -Multinodular goiter -Thyroid neoplasms.
Serum Thyroglobulin: • Increases dramatically in destructive processes of the thyroid gland, such as thyroiditis, or Graves' disease and toxic multinodular goiter • The most important use for serum Tg levels is in monitoring patients with differentiated thyroid cancer for recurrence, particularly after total thyroidectomy and RAI ablation. • Elevated anti-Tg antibodies can interfere with the accuracy of serum Tg levels and should always be measured when interpreting Tg levels.
Thyroid Imaging • Radionuclide Imaging Both iodine 123 and iodine 131 are used to image the thyroid gland. • Technetium Tc 99m pertechnetate:It is particularly sensitive for nodal metastases. • FDG PET is being increasingly used to screen for metastases in patients with thyroid cancer in whom other imaging studies are negative.
Thyroid Imaging Ultrasound: • It is helpful in the evaluation of thyroid nodules, distinguishing solid from cystic ones, and providing information about size and multicentricity. • USE FOR UNPLAPABLE NOUDUL F0R FNA. • Following benign NOUDUL
C Tscan/M R : *Particularly useful in evaluating the extent of large, fixed, or substernal goiters (which cannot be evaluated by ultrasound) and their relationship to the airway and vascular structures. *Noncontrast CT scans should be obtained for patients who are likely to require subsequent RAI therapy. If contrast is necessary.Therapy needs to be delayed by several months. * Combined PET-CT scans are increasingly being used for Tg-positive, radioactive iodine negative tumors.
Imaging • CT & MRI: Retrosternal Invasion Recurrent
Goiter • Thyroid gland that is at least twice its normal size. • Enlargement of the thyroid glad (diffuse goiter) or enlargement by one or more nodules (nodular goiter).
Goiter • Most patients with nontoxic goiters are asymptomatic, although patients often complain of a pressure sensation in the neck. compressive symptoms such as dyspnea and dysphagia ensue. • Patients also describe having to clear their throats frequently (catarrh). • Pemberton's sign-facial flushing and dilatation of cervical veins • Sudden enlargement of nodules or cysts due to hemorrhage may cause acute pain. • Deviation or compression of the trachea may be apparent.
Medical treatment • Most euthyroid patients with small, diffuse goiters do not require treatment. • Some physicians give patients with large goiters exogenous thyroid hormone to reduce the TSH stimulation of gland growth; this treatment may result in decrease and/or stabilization of goiter size and is most effective for small diffuse goiters. • Endemic goiters are treated by iodine administration.
Surgicalresection • (a)continue to increase despite T4 suppression, • (b) cause obstructive symptoms • (c) have substernalextension • (d) malignancy suspected or proven by FNAB • (e) cosmetically unacceptable. • Near-total or total thyroidectomy is the treatment of choice, and patients require lifelong T4 therapy
Graves' disease is characterized by: • 1-Thyrotoxicosis • 2- Diffuse goiter • 3-Extrathyroidal,conditions,including: ophthalmopathy,dermopathy,(pretibial myxedema),thyroid-acropachy,gynecomastia • The exact etiology of the initiation of the autoimmune process in Graves’ disease is not known • However, conditions such as the postpartum state,iodineexcess, lithium therapy, and bacterial and viral infections have been suggested as possible triggers
Diffuse Toxic Goiter (Graves' Disease): • Autoimmune disease • Strong familial predisposition • Female preponderance (5:1) • Ages of 40 to 60 years.
Diffuse Toxic Goiter (Graves' Disease): • Hyperthyroid symptoms include heat intolerance,increased sweating and thirst, and weight loss • Adrenergic stimulation include palpitations, nervousness, fatigue, emotional lability, hyperkinesis,and tremors. • GI symptoms include increased frequency of bowel movements and diarrhea.
Diffuse Toxic Goiter (Graves' Disease): • Amenorrhea, decreased fertility, and an increased incidence of miscarriages. • Children experience rapid growth with early bone maturation, whereas older patients may present with cardiovascular complications such as atrial fibrillation and congestive heart failure.
Diffuse Toxic Goiter (Graves' Disease): Tachycardia or atrial fibrillation is present with cutaneous vasodilation leading to a widening of the pulse pressure and a rapid falloff in the transmitted pulse wave (collapsing pulse). A fine tremor, muscle wasting, and proximal muscle group weakness with hyperactive tendon reflexes often are present.
Diffuse Toxic Goiter (Graves' Disease): Eye symptoms include • Lid lag (von Graefe's sign) • Spasm of the upper eyelid revealing the sclera above the corneosclerallimbus (Dalrymple's sign) • Prominent stare, due to catecholamine excess.
Diffuse Toxic Goiter (Graves' Disease): • True infiltrative eye disease results in periorbital edema, conjunctival swelling and congestion (chemosis), proptosis, limitation of upward and lateral gaze (from involvement of the inferior and medial rectus muscles, respectively), keratitis, and even blindness due to optic nerve involvement.
Etiology • The etiology of Graves‘ ophthalmopathy is not completely known; however, orbital fibroblasts and muscles are thought to share a common antigen, the TSHR.
Diffuse Toxic Goiter (Graves' Disease): • Gynecomastia is common in young men. • Rare bony involvement leads to subperiosteal bone formation and swelling in the metacarpals (thyroid acropachy). • Onycholysis, or separation of fingernails from their beds, is a more commonly observed finding. • On physical examination Thyroid is diffusely and symmetrically enlarged enlarged pyramidal lobe. bruit or thrill and loud venous hum in the supraclavicular space. The skin is warm and moist
Diffuse Toxic Goiter (Graves' Disease):Lab • The thyroid-stimulating antibodies stimulate the thyrocytes to grow and synthesize excess thyroid hormone, which is a hallmark of Graves' disease. • Elevated TSH-R or thyroid-stimulating antibodies (TSAb)are diagnostic of Graves' disease and are increased in about 90% of patients. • If eye signs are present, other tests are generally not needed. However,in the absence of eye findings, an 121 I uptake and scan should be performed.
Treatment Graves' disease may be treated by any of three treatment • Modalities-antithyroiddrugs • Thyroid ablation with radioactive 131 I and:The major advantages of this treatment are the avoidance of a surgical procedure and its concomitant risks, reduced overall treatment costs, and ease of treatment • Thyroidectomy The choice of treatment depends upon several factors, as discussed in the following sections.
Thyroidectomy surgery is recommended when RAI is contraindicated as in patients who • (a) Have confirmed cancer or suspicious thyroid nodules • (b) Are young • (c) Desire to conceive soon (<6 months) after treatment • (d) Have had severe reactions to antithyroidmedications • (e) Have large goiters (>80 g) causing compressive symptoms • (f) Are reluctant to undergo RAI therapy. Relative indications: particularly smokers, with Moderate to severe Graves ophthalmopathy those desiring rapid control of hyperthyroidism with a chance of being euthyroid,and those demonstrating poor compliance to antithyroidmedications. Pregnancy is also a relative contraindication, and surgery should be used only when rapid control is needed and antithyroidmedications cannot be used. Surgery is best performed in the second trimester.
Toxic Multinodular Goiter *Occur in older individuals, who often have a prior history of a nontoxic multinodular goiter. *Hyperthyroidism also can be precipitated by iodide-containing drugs such as contrast media and the antiarrhythmic agent amiodarone (jodbasedow hyperthyroidism).
