Thyroid Flashcards
(144 cards)
1
Q
What fills the follicels of the thyroid?
A
Colloid
2
Q
What cells line the follicles?
A
Cuboid epithelial cells
3
Q
What is the large glycoprotein in the colloid that contains thyroid hormones?
A
Thyroglobulin
4
Q
What is the big name for T4?
A
Thyroxine
5
Q
What is the big name for T3?
A
Triiodothyronine
6
Q
Which ion is trequired for the synthesis of T4?
A
Iodine
7
Q
Which H influences the iodide trapping by stimulating the iodide pump?
A
TSH
8
Q
What is the transporter on the basal membrane of the thyroid cells, which co-transports 1 iodide along with 2 sodiums into the cell from the plasma?
A
NIS
9
Q
True or False: since the NIS is a symporter, it doesnt require energy.
A
False
It uses secondary active transport, where the Na gradient is set up by an Na/K ATPase.
10
Q
What is the transporter molecule that transports iodide out of the thyroid cells and into the follicle?
A
Pendrin
Cl-I ion counter transport
11
Q
What is the enzyme that converts iodine to an oxidized form?
Hint: it’s associated with H2O2
A
Peroxidase
12
Q
What is the transporter that is secreted into the follicle that contains a large amount of Tyr, to which the oxidize iodine will bind?
A
Thyroglobulin
13
Q
What is the process of binding of thyroglobulin to iodine called?
A
Organification
14
Q
Fill in the blank:
Tyrosine –> monoiodotyrosine –> ________ –> ______
A
Diiodotyrosine
Thyroxine (T4)
15
Q
So how do u make T3?
A
1 MONOiodotyrosine + 1 DIiodotyrosine
16
Q
How many months of a supply does the thyroid gland store of T3/T4?
A
2-3 months
17
Q
What are the vesicles called that contain the T3/4 that are bound to the thyroglobulin?
A
pinocytic vesicles
18
Q
What fuses with the pinocytic vesicles to cleave the thyroglobulin and release T3/4?
A
Lysosomes (and their proteases)
19
Q
Since 3/4 of the iodinated tyrosine never become TH’s, what enzyme cleaves their iodine, which allows it to be recycled?
A
Deiondinase enzyme
20
Q
What % of TH’s are released as T4? as T3?
A
93% T4
7% T3
21
Q
What is the main hormone to bind to TH’s in the blood?
A
Thyroxine-binding globulin
22
Q
What is the half life of thyroxine and triiodothyronine?
A
Thyroxine- 6 days
Triiodothyronine- 1 day
23
Q
What is most of T4 converted into?
A
T3
24
Q
Where are the receptors for the TH’s?
A
Nucleus
25
What are the locations on the DNA where the TH's bind, to form a heterodimer with retinoic X receptor (RXR)?
Thyroid Hormone Response Elements (THRE's)
26
What happens to the metabolic activity in almost all tissues of the body in TH?
increase metabolic activity
27
What happens to the mitochondria under TH stimulation?
Increase in # and activity
28
What happens to the Na/K ATPases under the influence of TH?
they increase in activity
29
What happens to the growth in kids if they have hypothyroidism?
Growth retardation
30
What happens to the growth in kids if they have hyperthyroidism?
Excessive skeletal growth, however, the bone mature more rapidle --> epiphyses close earlier
31
What happens to the brain in kids if they have hypothyroidism?
MR because TH promotes growtha nd development of the brain during fetal life
32
What happens to the carb and fat metabolism under the influences of TH?
they increase
33
What happens to the plasma concentrations of cholesterol, phospholipids, and TG's in the plasma under the influence of TH's?
TH decreases them
34
What are the cardiovascular changesunder the influence of TH?
↑ blood flow, CO, HR, ionotropy
normal MAP
35
What happens to the muscles under the influence of TH?
Fine muscle tremor
36
What happens to the respiratory rate under the influence of TH?
it increases
37
What increases the release of TRH release from the hypothalamus?
Cold temperatures
38
What is the H that increases the proteolysis of thyroglobulin, activity of iodide pump, iodination of tyrosine, size and secretory activity of the thyroid cells, and the # of thyroid cells?
TSH
39
What G-protein goes TSH use?
Gs proteins (↑ cAMP)
40
What H inhibits TSH release?
TH
41
What is the drug that decreases iodide trapping by competitively inhibiting iodide transport into the cell?
Thiocyanate
42
The subsequent increases in TSH if using thiocyanate can cause what clinical manifestation?
Goiter
43
Propylthiouracil blocks what 2 things within the cell to prevent the formation of thyroglobulin?
Peroxidase enzyme
Coupling of iodinated tyrosinases
44
What drugs can ddecrease the thyroid activity and thyroid gland size by decreasing the rate of iodide trapping and also causing the endocytosis of the colloid to be paralyzed?
High concentrations of inorganic iodides
45
What is the most common cause of hyperthyroidism?
Graves disease
46
What is the pathogenesis of Graves?
Autoimmune thyrroid STIMULATING immunoglobulins against the TSH receptor
47
What type of hypersensitivity rxn is Graves?
type II NON-cytotoxic
| eventually turns cytotoxic and kills ur thyroid but initally it's one of the 3 non-cytotoxic type II
48
What happens to the blood TSH levels in Graves disease? are they high or low?
very LOW
49
What is the disease where a localized thyroid tumor secretes TH, leading to high TH and low TSH levels in the blood?
Thyroid adenoma
50
In addition to being super excitable, tremors, weight loss, diarrhea, and all that good stuff, what temperature are people with hyperthyroidism intolerant to?
Heat intolerance
| they're always hot, like Hansel.
51
This is the buzzword for hyperthyroidism where there is protrusion of the eyeballs due to edematous swelling o the retro-orbital tissues and degenerative changes in the extraocular muscles.
Exopthalamos
52
What is the most accurate test for hyperthyroidism?
Direct measurement of the conentration of free thyroxine in the plasma.
53
What are the 2 drugs given for several weeks prior to surgical removal of the thyroid, in order to lower the BMR, gland size, and blood supply?
Propylthiuouracil (↓ BMR)
High concentrations of iodides (↓ thyroid)
54
This is the disease where there is autoimmune destruction of the thyroid, leading to thyroiditis.
Hashiomotos
55
What type of sensitivity rxn is Hashimotos?
type IV
| totally different than Graves, which is type II non-cytotoxic
56
Why can a big ass goit develop if you have iodide deficiency?
no iodide --> no TH --> no neg feedback to pit and hypothal --> ↑ TSH --> ↑ thyroid stimulation --> ↑ production of thyroiglobulin --> GOIT
57
What disease can manifest from any deficiency in the TH production pathway?
idiopathic nontoxic colloid goiter
58
This is the condition where there is extreme hypothyroidism during fetal life, infancy, or childhood
Cretinism
59
What happens to the skeletal system and tongue in cretinism?
Skeletal- short, obese, stocky appearing
| Tongue- very large
60
In addition to fatigue, bradycardia, constipation, mental sluggishness, failure of many trophic functions, and getting a frog-voice (ribbit), what temperature intolerance do u have in hypothyroidism?
Cold intolerance
(remember the stimulus for TH release is cold temperatures, so if u have hypothyroidism and u cant secrete TH, when u step out into the cold Erie, u cant regulate it, so ur intolerant to cold. ya hear?)
61
This is the buzzword for hypothyroidism where there is an edematous appearance throughout the body because of ↑ hyaluronic acid and chondoitin sulfate in the IF.
Myxedema
| myxEDEMA. EDEMA. EDEMA.
62
In hyperthyroidism, the lack of TH increases the quantity of blood cholesterol because of altered fat and cholesterol metabolism, which increases the risk for what problem?
Atherosclerosis
63
What is the general treatment for hypothyroidism?
Oral tablet containing thyroxine
64
How can we use TSH levels to distinguish between Graves and Hashimotos?
They'll be HIGH in Hashimotos and LOW in Graves.
Both diseases are autommune but Graves causes hyperthyroidism, leading to increased TH release, which ↑ the neg inhibition back to the pituitary, which ↓ TSH. In hashimotos, the autoimmune destruction of the thyroid causes ↓ TH release, which ↓ neg inhbition to the thyroid, which ↑ TSH release.
65
This is the cystic dilation of the thyroglossal duct that presents as an anterior neck mass.
Thyroglossal duct cyst
66
This is the persistence of thyroid tissue at the base of the tongue.
Lingual thyroid
67
Which proteins are upregualted in hyperthyroidism, which causes the ↑ BMR?
Na/K ATPases
68
Which R's are upregulated in hyperthyroidism, which increases sympathetic nervous system activity?
B1 adrenergic R's
69
This is the potentially fatal complication of Graves where elevated catecholamines and massive hromone excess causes arrhythmia, hyperthermia, vomiting, and hypovolemic shock.
Thyroid storm
70
What 3 drugs are used to treat thyroid storm?
PTU, B-blockers, and steroids
71
Which drug for the Tx of thyroid storm inhibits peroxidase-mediated oxidation, organification, and coupling steps of thyroid hormone synthesis, and peripheral conversion of T4 --> T3?
PTU
72
This is the condition where there is an enlarged thyroid gland with multiple nodules.
Multinodular goiter
73
What is the most common cause of a multinodular goiter?
Relative iodine deficiency
74
This is a rare complication of a multinodular goiter where there are regions of TSH-independence, leading to T4 release and hyperthyroidism.
Toxic goiter
75
This is the condition where there is MR, short stature, coarse facial features, enlarged tongue,a nd an umbilical hernia in kids.
Cretinism.
76
What are the 4 main causes of cretinism>
Materal hypothyroidism during early pregnancy
Thyroid agenesis
Dyshormonogenetic goiter
Iodine deficiency
77
What is the most common cause of myxedema where Iodine is sufficiency?
Hashimotos thyroiditis
78
What is the HLA subtype that is associated with Hashimotos?
HLA-DR5
| same one as Pernicious Anemia
79
Bonus: what is the HLA subtype associated with Graves?
HLA-DR3
| same one as DM1
80
Though Hashimotos causes autoimmune destruction and subsequent hypothyroidism, what can be the initial presentation due to follicular damage?
Hyperthyroidism
81
What 2 autoantibodies are associated with Hashimotos?
Antimicrosomal and Antithyroglobulin
"-Micro- -thyroid-"
82
This is the eosinophilic metaplasia of cells that line the follicles, as seen with germinal centers in Hashimotos.
Hurthle cells
83
Case: a 50 y/o woman with a long History of Hashimotos presents to your office with an enlarging thyroid gland. You find this suspicous as her thyroid has been destroyed by autoimmune destruction, but realize that this coudl be a manifestation of what late course disease?
B-cell (marginal zone) lymphoma
84
Case: pt presents with a tender thyroid and transient host flashes with tachycardia. He states he just got done recovering from a respiratory infection a few days ago. What cells would you see on biopsy?
Granulomatous thyroiditis
| Subacute Granulomatous (de quervain) thyroiditis
85
True or False: De Quervains thyroiditis typically progresses to hypothyroidism.
False.
It's usually self-limited
86
This is the condition where there is chronic inflammation of the thyroid gland with extensive fibrosis.
Reidel fibrosing thyroiditis
87
What is the class Sx for Reidel fibrosing thyroiditis?
hypothyroidism with a "hard as wood" nontender thyroid
88
Since Reidel fibrosing thyroiditis can invade local structures, it can mimic which disease?
Anaplastic carcinoma
89
But wait! how can we distinguish Reidel fibrosing thyroiditis from Anaplastic carcinoma? What age do Reidel fibrosing thyroiditis pts get affected?
pts in their 40s
| anaplastic carcinoma affects old ppl
90
What type of study can u do to characterize thyroid nodules?
(131)I radioactive uptake studies
91
What are the 2 likely causes if you find a Hot nodule on a (131)I radioactive uptake study?
Graves or Nodular goiter
92
What are the 2 likely causes if you find a Cold nodule on a (131)I radioactive uptake study?
Adenoma or Carcinoma
93
What is the type of needle do you need to biopsy the thyroid, which is important because of the hypervascular nature of the thyroid gland?
Fine Needle Aspiration (FNA)
94
This is the benign proliferation of follicles surrounded by a fibrous CAPSULE, and is usually nonfunctional.
Follicular Adenoma
95
What is the most common type of thyroid carcinoma?
Papillary carcinoma
96
What is the biggest risk factor for getting papillary carcinoma?
Exposure to ionizing radiation in childhood
97
What are the 2 buzzwords for nuclear morphologies in papillary carcinomas?
Orphan Annie eye nuclei
Nuclear grooves
98
What are the things called in papillary carcinomas where there are calcification along the papillae?
Psammoma bodies
99
Even through papillary carcinomas can spread to the cervical lymph nodes, what is the prognosis?
Excellent
| 10-year survival > 95%
100
This is the malignant proliferation of follicles surrounded by a fibrous capsule with INVASION through the capsule?
Follicular Carcinoma
| remember, in follicular adenomas, there is no invasion through the capsule
101
True or False: follicular adenoma and carcinoma can be distinguished using FNA.
FALSE
FNA will jsut show cells, not the capsule, and invasion through the capsule is indicitive of carcinoma)
102
Where does metastasis usually occur in follicular carcinoma?
Hematogenously (blood)
103
This is the malignant proliferation of parafollicular C cells, causing the massive release of calcitonin,
Medullary carcinoma
104
In addition to hypocalcemia, what does calcitonin get deposited as in medullary carcinoma?
Amyloid
105
What is the high-yield term for the "sheets" in medullary carcinoma?
Sheets of malignant cells in an amyloid stroma
106
The familial causes of medullary carcinoma are often due to MEN2A and 2B, whcih have a mutation in which gene?
RET gene
107
Which coniditon result in medullary carcinoma, pheochromocytoma, parathyroid adenomas (A), or ganglioneuromas of the oral mucosa (B).
MEN2
108
This is the undifferentiated malignant tumor of the thyroid, usual invasion of local structures, and usually seen in the elderly.
Anaplastic carcinoma
109
And what condition does anaplastic carcinoma look like, but is in the young and has no malignant cells?
Reidel fibrosing thyroiditis
110
THis is the localized, infiltrative dermaopathy on the shins in Graves pts.
Pretibial myxedema
111
This is the L-isomer of T4 and is given once a day to treat hypothyroidism.
Levothyroxine
112
What time is levothyroxine not used?
For myxedema coma, where we need to administer T3 for its rapid effects
113
What is the T3 drug that is used for myxedema coma?
Liothyronine
114
What is the radioactive isotope of iodide that emits B-particles to treat hyperthyroidism?
(131)I-
115
What is the main problem for using 131I- to treat hyperthyroidism?
It may destroy too much tissue, leading to hypothyroidism
116
This is the effect that high levels of iodide inhibits thyroid hormone synthesis and release.
Wolff-Chaikoff effect
117
What makes the Wolff-Chaikoff effect different than 131I-?
Wolff-Chaikoff effect uses a stable inorganic iodide
| just normal everyday I-, just a butt load of it
118
What is downregulated by negative feedback with high levels of iodide, leading to the Wolff-Chaikoff effect?
Na/I symporter
119
When is the Wolff-Chaikoff effect utilized in the medical field?
you give high levels of I to reduce the size and vascularity of the thyroid before a thyroidectomy
also used in radioactive spills cuz u downregulate the NIS so u dont take up as much radioactive I
120
What are the 2 thioamines that inhibit thyroid H production by decreasing organification?
Propylthiouracil and methimazole
121
What is the main problem with Propylthiouracil and methimazole treament?
Goiters
122
Which drug (Propylthiouracil or methimazole) can be given once daily, whereas the other requires 3 doses daily?
Methimazole- once daily
| Propylthiouracil- 3x daily
123
Which drug (Propylthiouracil or methimazole) has serious sides like severe hepatitis leading to liver failure and death?
Propylthiouracil
124
What are the 2 B-blockers that are used to treat the Sx of HTN in hyperthyroidism?
Propanolol and esmolol
125
Since esmolol is a short-acting B-blocker and has to eb given IV, what "condition" is it used to treat in the ER setting?
Thyroid storm
126
What is the antiarrhythmic drug that can positively and negatively affect thyroid hormone fxn?
Amiodarone
127
What does amiodarone contain, which allows its use to treat hyperthyroidism?
Hint: think WC effect
amiodarone has large amts of Iodine
128
In type 1 thyrotoxicosis, what is stimulated by the use of amiodarone?
excess iodide leads to ↑ TH synthesis and release
129
What is induced in type 2 thyroiditis in amiodarone treatment?
an autoimmune thyroiditis is induced
130
Which type of thyroid disease (primary or secondary) causes DECREASED TSH levels in the blood?
Secondary thyroid disease
| ant pit is screwed up --> no TSH release
131
What is the immune marker for Graves disease?
TSH receptor stimulating immunoglobulins (TSIs)
132
THis is the condition where there is a self-limiting painless lymphocytic thyroiditis that occurs most commoly in the postpartum period.
Postpartum thyroiditis
133
True or False: postpartum thyroiditis has a tendency to reoccur with subsequent pregnancies.
True
134
What is the triphasic pattern commonly seen in postpartum thyroiditis?
initial hyperthyroid phase --> hypothyroid phase --> recovery of normal thyroid function
135
A PAINFUL TENDER thyroid is like super big in what specific disease that you should know like super well?
de Quervain thyroiditis
| like the de Quervain tenosynovitis in the wrist, like painful shit
136
This is the condition where there is hyperthyroidism from exogenous use of T3/T4.
Factitial thyrotoxicosis
137
What salt is given to treat thyroid storm by inhibiting the release of TH?
NaI
138
What electrolyte abnormality may eb present in hypothyroidism?
Hyponatremia
139
What is the condition where TSH levels are increased in patients with a normal FT4 concentrations?
Subclinical hypothyroidism
140
This is the condition in pts who have severe, untreated hypothyroidism, has a high mortality rate, and is characterized by a progressive stupor, culminating in coma.
Myxedema coma
141
What % of thyroid nodules are benign?
95%
142
Which type of thyroid cancer has an extremely poor prognosis?
Anaplastic carcinoma
143
This is the condition where hospitalized pts with a systemic illness have an abnormal thyroid function, and typically resolves after the illness resolves.
Sick euthyroid syndrome
| Euthyroid = eu (good) + thyroid
144
What is the antipsychotic drug that can cause hypothyroidism by decreasing the synthesis and secretion of thyroid hormones?
Lithium
| seriously who takes this stuff? causes nephrogenic DI and now hypothyrodism... gnarly.
