Thyroid gland
Endocrine abnormalities
Hyperthyroidism

Author: Anthony Chi, M.D. and Julie Guilmette, M.D. (see Authors page)

Revised: 29 September 2016, last major update September 2016

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed Search: Endocrine abnormalities hyperthyroidism

See also Clinical Chemistry chapter
Cite this page: Hyperthyroidism. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/thyroidhyper.html. Accessed December 6th, 2016.
Definition / General
  • Increased thyroid hormone synthesis and secretion from the thyroid gland (Lancet 2016;388:906)
Epidemiology
Pathophysiology
  • Depends upon the underlying cause
  • Graves' disease (Cochrane Database Syst Rev 2015 Nov;11:CD010576):
    • Autoimmune disease caused by the production of auto antibodies against thyroid stimulating hormone receptors
    • Stimulation of follicular cells to produce thyroid hormone


Types
Etiology
  • Graves’ disease (85%) or maternal Graves’ disease, overdose of thyroid hormone, iodide ingestion, hyperfunctioning multinodular goiter or thyroid adenoma, thyroiditis, struma ovarii, choriocarcinoma, hydatidiform mole, pituitary adenoma (Lancet 2016;388:906)
  • Radiocontrast iodine based agent (Arch Endocrinol Metab 2016;60:287)
Clinical Features
  • Early symptoms: anxiety, palpitations, rapid pulse, fatigue, muscle weakness, weight loss, diarrhea, hyperactive reflexes, increased sweating, heat intolerance, warm skin, excessive perspiration, menstrual changes, hand tremor, polydipsia and increased appetite (J Am Geriatr Soc 1996;44:50)
  • Late symptoms: cardiac (palpitations, congestive heart failure, cardiomegaly, atrial fibrillation, fatty change), fatty change of skeletal muscle or liver, osteoporosis from bone resorption, generalized lymphadenopathy
  • Ocular changes: wide staring gaze and lid lag due to sympathetic overstimulation of levator palpebrae superioris
  • Thyrotoxicosis: hypermetabolic clinical syndrome due to elevated serum T3 or T4
    • May be due to hyperthyroidism, thyroiditis or excessive ingestion of thyroid hormone (“factitious hyperthyroidism”)
    • Includes a wide range of symptoms, such as ophtalmopathy, dermatopathy, fever, marked tachycardia, heart failure, tremor, nausea, vomiting, diarrhea, dehydration, restlessness, extreme agitation, delirium and coma (Endotext-hypothyroidism, CMAJ 2003;168:575)
    • In severe thyrotoxicosis, death may be secondary to cardiac failure, shock and multiple organ failure (Endotext-hypothyroidism)
Laboratory
  • Low or suppressed TSH, elevated free thyroxine level (FT4) (CMAJ 2003;168:575)
  • 10% of patients have an increased total or free T3 level and normal T4 level with suppressed TSH level, a condition called ‘T3 toxicosis’ (CMAJ 2003;168:575)
  • In Graves’ disease, elevated levels of antitopoisomerase antibodies and antithyroglobulin antibodies are found in 80% and 50% of cases, respectively (Mod Pathol 2000;13:1014)
Radiology Description
  • Scintigraphy with Tc - 99m pertechnetate shows an enlarged thyroid gland with an increased activity level diffusely through the gland (Radiographics 2003;23:857)
Case Reports
Treatment
  • Treatment options for Graves’ disease include antithyroid drugs (such as carbimazole, methimazole, or propylthiouracil / PTU), radioactive iodine therapy and surgery (Lancet 2016;388:906)
  • Beta blockers for symptoms, thionamide type drugs to block new hormone synthesis, iodine to block release of T4 / T3, radioactive iodine to destroy thyroid tissue
  • Thyroidectomy if other treatments fail or are contraindicated, or when goiter is causing compressive symptoms (Am Fam Physician 2005;72:623)
Gross Description
Gross Images

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Graves Disease

Micro Description
  • Papillary hyperplasia and fronds that may lack true fibrovascular cores (Mod Pathol 2000;13:1014), mimicking papillary thyroid carcinoma
  • Follicles are hypercellular and lined by tall columnar epithelium
  • Treatment may cause follicular cells to become cuboidal rather than columnar
  • Limited to absent fibrosis
  • Mixed, but predominantly lymphocytic infiltrate, within stroma surrounding follicles.
  • Small or occluded lumens containing pale or little colloid
  • Scalloping of the colloid
  • Nuclear features of papillary carcinoma are lacking
Micro Images

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Multinodular Goiter

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Diffuse hyperplasia of thyroid gland

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