Thyroid Flashcards
The thyroid combines _ and _ to produce thyroid hormones
The thyroid combines iodine and tyrosine to produce thyroid hormones
Symptoms of increased metabolic activity, such as heat intolerance, sweating, insomnia, weight loss, palpitations, anxiety, and diarrhea are all suggestive of _
Symptoms of increased metabolic activity, such as heat intolerance, sweating, insomnia, weight loss, palpitations, anxiety, and diarrhea are all suggestive of hyperthyroidism
The bilateral recurrent laryngeal nerves branch off of the bilateral vagus nerves to innervate all intrinsic muscles of the larynx aside from the _ muscle
The bilateral recurrent laryngeal nerves branch off of the bilateral vagus nerves to innervate all intrinsic muscles of the larynx aside from the cricothyroid muscle
The thyroid is a butterfly gland anterior to the trachea and inferior to the _ cartilage
The thyroid is a butterfly gland anterior to the trachea and inferior to the cricoid cartilage
The superior thyroid artery is a branch off of the _
The superior thyroid artery is a branch off of the external carotid artery
* Brachiocephalic –> left common carotid –> left external carotid –> left superior thyroid artery
The inferior thyroid arteries branch off of the _
The inferior thyroid arteries branch off of the subclavian arteries
The nerve that runs closest to the thyroid is the _
The nerve that runs closest to the thyroid is the recurrent laryngeal nerve
The recurrent laryngeal nerve is a branch of the _ nerve; it runs near the (inferior/superior) thyroid artery
The recurrent laryngeal nerve is a branch of the vagus; it runs near the inferior thyroid artery
Damage to the recurrent laryngeal nerve (from thyroidectomy) may result in _ or _
Damage to the recurrent laryngeal nerve (from thyroidectomy) may result in hoarseness or dysphagia
The thyroid gland produces both T3 and T4, however it produces more _
The thyroid gland produces both T3 and T4, however it produces more T4
* T4 gets converted to T3 which is more biologically active
Iodine deficiency will manifest as a _
Iodine deficiency will manifest as a goiter
* The thyroid enlarges, looking for more iodine
T3 is the regulator of _
T3 is the regulator of metabolism, temperature, weight, muscle strength, nervous system
(Hyperthyroidism/Hypothyroidism) is associated with gynecomastia or abnormal uterine bleeding
Hyperthyroidism is associated with gynecomastia or abnormal uterine bleeding
* Thyroid hormones increase sex hormone binding globulin –> decreases free testosterone –> promotes aromatization of androgens –> estrogens
* Note that menstrual irregularities are associated with both hyper and hypothyroidism
T3 and T4 synthesis occurs in the _
T3 and T4 synthesis occurs in the thyroid follicles
T4 gets converted to T3 _ where?
T4 gets converted to T3 in the periphery
Iodine gets organified and coupled to _ to make T4
Iodine gets organified and coupled to 2 Diiodotyrosine (DIT) to make T4
Iodine gets organified and coupled to _ to make T3
Iodine gets organified and coupled to 1 DIT + 1 monoiodotyrosine (MIT) to make T3
The first step of thyroid synthesis is the uptake of _ into follicular cells
The first step of thyroid synthesis is the uptake of iodide (I-) into follicular cells
After the uptake of iodide the iodide goes through _ and _
After the uptake of iodide the iodide goes through oxidation and organification
The enzyme responsible for oxidation, organification, and coupling is _
The enzyme responsible for oxidation, organification, and coupling is thyroid peroxidase
Thyroid peroxidase (TPO) is active in the _
Thyroid peroxidase (TPO) is active in the colloid of the thyroid
The thyroid hormone substrate which is formed by tyrosine + iodine is called _ ; it later gets coupled to MIT and DIT and then cleaved to release T3 and T4
The thyroid hormone substrate which is formed by tyrosine + iodine is called thyroglobulin ; it later gets coupled to MIT and DIT and then cleaved to release T3 and T4
_ binds T3 and T4 in the serum to prevent its destruction
Thyroid binding globulin binds T3 and T4 in the serum to prevent its destruction
Thyroid binding globulin is produced by the _
Thyroid binding globulin is produced by the liver
_ converts T4 –> T3 in the peripheral tissues
5’ Deiodinase converts T4 –> T3 in the peripheral tissues
When iodine administration inhibits T3 and T4 synthesis and causes hypothyroidism, we call this _
When iodine administration inhibits T3 and T4 synthesis and causes hypothyroidism, we call this Wolff-Chaikoff effect
When iodine adminstration causes uncontrolled T3 and T4 synthesis, we call this _
When iodine adminstration causes uncontrolled T3 and T4 synthesis, we call this Jod-Basedow phenomenon
In the Wolff-Chaikoff effect, the administration of iodine inhibits thyroid hormone synthesis for days via _ mechanism
In the Wolff-Chaikoff effect, the administration of iodine inhibits thyroid hormone synthesis for days via formation of iodopeptides –> inhibition of TPO synthesis
_ can be given for treatment of acute radiation exposure; this takes advantage of the _ phenomenon
Potassium iodide can be given for treatment of acute radiation exposure; this takes advantage of the Wolff-Chaikoff effect
The Jod Basedow phenomenon is most likely to occur in patients with _
The Jod Basedow phenomenon is most likely to occur in patients with dysregulated thyroid hormone synthesis
* Ex: patients with Graves, toxic multinodular goiter, thyroid adenoma
* These patients already have hyperthyroidism; when given iodine the synthesis of T3 and T4 is out of control
Propylthiouracil is an antithyroid medication that works via _
Propylthiouracil (PTU) is an antithyroid medication that works via inhibition of thyroid peroxidase
* Pro-pyl-thio-uracil
Side effects of Propylthiouracil (PTU) include:
Side effects of Propylthiouracil (PTU) include:
* Agranulocytosis
* Aplastic anemia
* Hepatotoxicity
Methimazole is an antithyroid medication that works via _
Methimazole is an antithyroid medication that works via inhibition of thyroid peroxidase
Methimazole side effects include:
Methimazole side effects include:
* Aplasia cutis (first trimester)
* Present in breast milk
_ , _ , _ , and _ are all 5’ Deiodinase inhibitors that inhibit the conversion of T4 –> T3 in the peripheral tissues
Glucocorticoids , beta blockers , PTU , and amiodarone are all 5’ Deiodinase inhibitors that inhibit the conversion of T4 –> T3 in the peripheral tissues
How does lithium affect the thyroid?
Lithium inhibits iodide uptake & TPO & T3/T4 release
* It can cause hypothyroidism or hyperthyroidism
Perchlorate/Pertechnetate is an antithyroid medication that _
Perchlorate/Pertechnetate is an antithyroid medication that inhibits iodine uptake
Graves disease is caused by _
Graves disease is caused by thyroid stimulating IgG which binds to TSH receptors –> T3, T4
Graves disease is a type _ hypersensitivity reaction
Graves disease is a Type II hypersensitivity reaction
Graves disease is associated with _ genetic markers
Graves disease is associated with HLA-DR3, HLA-B8
Graves disease is classically associated with _ eye finding
Graves disease is classically associated with exophthalmos
Explain the pathogenesis of exophthalmos
- T cell activation
- Lymphocyte infiltration into retro-orbital space
- Increased cytokines (TNF-a, INF-gamma)
- Increased fibroblast secretion of GAGs
- Muscle inflammation, osmotic muscle swelling
Graves: tall, crowded columnar follicular epithelial cells, scalloping
_ is the most common cause of hyperthyroidism in the US
Graves is the most common cause of hyperthyroidism in the US
* Very common in females 20-40
Graves disease may present with unique sx such as _ , _ and exophthalmos
Graves disease may present with unique sx such as goiter , pretbial myxedema and exophthalmos
Pretibial myxedema in graves disease is caused by _
Pretibial myxedema in graves disease is caused by activation of fibroblasts that deposit extra collagen
* Non-pitting edema
* Redness
Graves disease is associated with:
_ T3
_ T4
_ TSH
Graves disease is associated with:
High T3
High T4
Low TSH
In addition to normal thyroid labs, graves disease may be diagnosed via the presence of _
In addition to normal thyroid labs, graves disease may be diagnosed via the presence of anti-TSH receptor antibodies
Graves disease will present with _ on scintigraphy
Graves disease will present with diffuse uptake on scintigraphy
In graves disease, lipid panel may show _ and CBC may show _
In graves disease, lipid panel may show low cholesterol, low TGs and CBC may show normocytic anemia
_ is an uncommon, life-threatening complication of untreated hyperthyroidism that is usually brought on by acute stress
Thyroid storm is an uncommon, life-threatening complication of untreated hyperthyroidism that is usually brought on by acute stress
* Agitation, fever, delirium, coma, diarrhea, tachyarrhythmia
Treatment for thyroid storm:
Treatment for thyroid storm:
1. Propranolol (beta blockers)
2. Prophylthiouracil
3. Prednisolone (steroids)
4. Potassium iodide
A baby born to a mother with graves disease is at risk of _
A baby born to a mother with graves disease is at risk of fetal hyperthyroidism
* Thyroid stimulating immunoglobulin can cross the placenta and cause hyperthyroidism in utero
* Predisposes them to low birth weight, prematurity, death
A pregnant woman with Graves disease should be medically managed with _ in the first trimester and _ after the first trimester
A pregnant woman with Graves disease should be medically managed with PTU in the first trimester and methimazole after the first trimester
Acute sympathetic symptoms of hyperthyroidism may be managed with _
Acute sympathetic symptoms of hyperthyroidism may be managed with propranolol (for palpitations, muscle weakness, etc)
Toxic multinodular goiter is caused by _
Toxic multinodular goiter is caused by focal patches of hyperfunctioning follicular cells that work independently of TSH
* TSH is still low due to high T3,T4 but follicular cells continue to spit out thyroid hormone
Toxic multinodular goiter can be diagnosed via:
_ TSH
_ T3
_ T4
Toxic multinodular goiter can be diagnosed via:
Low TSH
High T3
High T4
The most common cause of toxic multinodular goiter is _
The most common cause of toxic multinodular goiter is TSH receptor mutation
Hyperthyroidism caused by TSH receptor mutation is likely to be associated with _ type goiter
Hyperthyroidism caused by TSH receptor mutation is likely to be associated with goiter with multiple nodules (not smooth)
Name three things that might be on your ddx for goiter
Name three things that might be on your ddx for goiter:
1. Iodine deficiency
2. Graves
3. Toxic multinodular goiter
Toxic multinodular goiter will show up as _ on thyroid scintigraphy
Toxic multinodular goiter will show up as “hot” nodules with increased iodine uptake on thyroid scintigraphy
Three management options for toxic multinodular goiter:
Three management options for toxic multinodular goiter:
1. Radioactive iodine ablation
2. Surgical removal
3. Thionamides
Extrinsic thyroid ingestion will show the following labs:
_ T3
_ T4
_ TSH
_ Thyroglobulin
_ 24 hour radioiodine uptake
Extrinsic thyroid ingestion will show the following labs:
High T3
High T4
Low TSH
Low/Normal Thyroglobulin
Low/Undetectable 24 hour radioiodine uptake
Two additional findings may help to differentiate an extrinsic ingestion of thyroid hormone, _ and _
Two additional findings may help to differentiate an extrinsic ingestion of thyroid hormone, low thyroglobulin levels and low 24-hour radioiodine uptake
Amiodarone is an anti-arrythmic drug that can cause hyper or hypothyroidism due to it containing _
Amiodarone is an anti-arrythmic drug that can cause hyper or hypothyroidism due to it containing iodine
* Jod Basedow: autonomous thyroid hormone synthesis
* Wolff-Chaikoff: hypothyroid state
In general, thyroiditis causes (hyper/hypo) thyroidism
In general, thyroididis causes hypothyroidism but often after a transient state of hyperthyroidism
Pregnancy may lead to a _ (hyper/hypo) thyroidism
Pregnancy may lead to a clinically insignificant hyperthyroidism
Increased estrogen during pregnancy causes an increase in _ , causing its thyroid effects
Increased estrogen during pregnancy causes an increase in thyroid binding globulin
* Increased circulating T3,T4 bound to TBG
* Free hormone levels are unchanged
* Not clinically significant (no sx)
Severe hypothyroidism may lead to _
Severe hypothyroidism may lead to myxedema coma
* AMS
* Hypothermia
* Slowing/Failure of multiple organs
The most common cause of hypothyroidism in idodine sufficient countries is _
The most common cause of hypothyroidism in idodine sufficient countries is Hashimoto’s
Hashimoto’s thyroiditis is caused by _
Hashimoto’s thyroiditis is caused by auto-antibodies against thyroid peroxidase (TPO) or thyroglobulin
Hashimoto’s involves two HSR, first type _ hypersensitivity reaction, followed by _
Hashimoto’s involves two HSR, first Type IV hypersensitivity reaction, followed by Type II HS
Explain the pathophysiology of Hashimoto’s
Explain the pathophysiology of Hashimoto’s:
1. CD8+ cytotoxic T cells attack the thyroid (Type IV)
2. Release TPO and thyroglobulin
3. Antibody formation (Type II)
4. Futher thyroid destruction
Hashimoto’s thyroditis is associated with _ genetic markers
Hashimoto’s thyroditis is associated with HLA-DR3, HLA-DR5
HLA-B8 is associated with (Graves/Hashimoto’s)
HLA-B8 is associated with Graves
HLA-DR5 is associated with (Graves/Hashimoto’s)
HLA-DR5 is associated with Hashimoto’s
* Both of them are associated with HLA-DR3
A hashimoto thyroid may feel _
A hashimoto thyroid may feel nontender, enlarged, symmetrical, “rubbery”
What is hashitoxicosis?
Hashitoxicosis may occur in the first stage of Hashimoto’s when we have transient hyperthyroidism from the release of lots of T3 and T4
Hashimoto’s labs:
_ T3
_ T4
_ TSH
_ Thyroglobulin
Hashimoto’s labs:
High then Low T3
High then Low T4
Low then High TSH
High then ? Thyroglobulin
Two classical histologic findings in Hashimoto’s thyroiditis are _ and _
Two classical histologic findings in Hashimoto’s thyroiditis are Hurthle cells and lymphoid aggregates with germinal centers
Hashimoto’s is managed with _
Hashimoto’s is managed with levothyroxine
Postpartum thyroiditis is very similar to _
Postpartume thyroiditis is very similar to Hashimoto’s
* Subacute lymphocytic thyroiditis
* Shares the same pathophysiology as Hashimoto’s but brought on by pregnancy, up to one year after delivery
Thyroid adenoma presents on histology as _
Thyroid adenoma presents on histology as follicular changes but no capsular or vascular invasion
* Increased variability of the follicle size
The thyroid is derived from _ (layer) between the _ and _ pharyngeal pouches near the base of the tongue
The thyroid is derived from endoderm between the second and third pharyngeal pouches near the base of the tongue
The base of the tongue, where the thyroid descends downward from is called the _
The base of the tongue, where the thyroid descends downward from is called the foramen cecum
The thyroid descends (anterior/posterior) to the hyoid bone
The thyroid descends anterior to the hyoid bone
The _ is a structure that connects the thyroid and tongue during caudal migration from the foramen cecum
The thyroglossal duct is a structure that connects the thyroid and tongue during caudal migration from the foramen cecum
The dorsal wings third pharyngeal pouch becomes the _
The dorsal wings third pharyngeal pouch becomes the inferior parathyroid glands
The dorsal wings fourth pharyngeal pouch becomes the _
The dorsal wings fourth pharyngeal pouch becomes the superior parathyroid glands
The ventral wing of the fourth pharyngeal pouch gives rise to the _
The ventral wing of the fourth pharyngeal pouch gives rise to the parafollicular C cells
Faulty migration or persistence of the thyroglossal duct may give rise to _ or _
Faulty migration or persistence of the thyroglossal duct may give rise to thyroid ectopia or thyroglossal duct cysts
The parathyroids develop from the _ and _ pharyngeal pouches
The parathyroids develop from the third and fourth pharyngeal pouches
Papillary thyroid carcinoma
Follicular carcinoma
Anaplastic thyroid carcinoma
The right and left lobes of the thyroid are connected via the _
The right and left lobes of the thyroid are connected via the isthmus
Some individuals have a _ , which is just the persistence of thyroid tissue in the inferior segment of the thyroglossal duct
Some individuals have a pyramidal lobe , which is just the persistence of thyroid tissue in the inferior segment of the thyroglossal duct
The parathyroid glands are small glands (the size of a grain of rice) located at the _
The parathyroid glands are small glands (the size of a grain of rice) located at the posterior side of the thyroid
Arrows are pointing to _ cells
C cells (parafollicular cells)
Normal thyroid follicles are lined with _ and filled with _
Normal thyroid follicles are lined with follicular epithelium and filled with colloid
Multinodular goiter:
Left shows hyperplasia, top right shows colloid accumulation, bottom right shows nodule formation
The most common cause of hypothyroidisim is _
The most common cause of hypothyroidism is Hashimoto thyroiditis aka chronic lymphocytic thyroiditis
Hurthle cells
Reidel thyroiditis is an autoimmune condition associated with _ antibody
Reidel thyroiditis is an autoimmune condition associated with IgG4
De Quervain thyroiditis
_ is a benign mass that origintes from the thyroid follicular cells; it is a well circumscribed nodule with a fibrous capsule
Follicular adenoma is a benign mass that origintes from the thyroid follicular cells; it is a well circumscribed nodule with a fibrous capsule
Criteria for diagnosing follicular carcinoma requires that there is _ and _
Criteria for diagnosing follicular carcinoma requires that there is invasion into blood vessels and invasion through the capsule
Follicular nuclei may have _ or _ in papillary thyroid carcinoma
Follicular nuclei may have elongation/overlapping or dispersed chromatin (clearing) in papillary thyroid carcinoma
Psammoma bodies are also associated with _ thyroid neoplasm
Psammoma bodies are also associated with papillary thyroid carcinoma
Anaplastic thyroid carcinoma
Medullary thyroid carcinoma will have a _ appearnace
Medullary thyroid carcinoma will have a neuroendocrine appearance with “packets” of uniform round/oval cells
Identify A
A: Normal
Identify B
B: Grave’s disease
Identify C
C: toxic multinodular goiter
Identify D
D: toxic adenoma
Identify E
E: thyroiditis
Onycholysis is _
Onycholysis is separation of the nail from the nail bed, sign of hyperthyroidism
Hyperactive thyroid nodule
