Thyroid Flashcards
1
Q
what is the main function of the thyroid?
A
helps regulate metabolism
2
Q
what releases TRH?
A
hypothalamus when senses body needs T4/T3
3
Q
what happens when the hypothalamus releases TRH?
A
TRH signals to anterior pituitary to secrete TSH
4
Q
what releases TSH?
A
anterior pituitary
5
Q
what happens when anterior pituitary releases TSH?
A
TSH tells thyroid to release thyroxine
6
Q
what is the active form, T4 or T3?
A
T3
7
Q
what converts T4 to T3?
A
iodine
8
Q
what does a deficiency in iodine lead to?
A
a large thyroid b/c it keeps trying to produce the hormones, but there is no iodine there to convert it
9
Q
what is thyrotoxicosis?
A
elevated unbound (“free”) thyroid hormone circulating in the body
10
Q
what is the #1 cause of hyperthyroidism in the US?
A
Graves Disease
- women>men
- 20-40 y/o
11
Q
what is Graves Disease
A
autoimmune disorder
- increase and synthesis of release of both T4 and T3 from the thyroid
- thyrotropin antibodies bind to TSH receptor to stimulate gland to keep secreting T4 and T3 (excess T4/T3)
12
Q
what can exacerbate Graves disease?
A
Life stressors can exacerbate Graves Disease if patient is in remission
13
Q
is Graves disease familial?
A
Yes, Familial tendency to get Graves Disease
14
Q
other 2 causes of hyperthyroidism?
A
Toxic Multinodular Goiter (15-30%)
Toxic Nodular Goiter
-both are hyperplasia of thyroid cells that are functioning on their own (no feedback loops)
15
Q
what type of adenoma can also cause hyperthyroidism? what are the levels of TSH like?
A
pituitary adenoma
-TSH/T4/T3 levels are high
(in hyperthyroidism, TSH is low)
16
Q
common symptoms of hyperthyroidism?
A
Sweating, heat intolerance, palpitations, SOB (due to palpitations, weight loss (despite increase in hunger)
HYPERACTIVITY
17
Q
what will you find on hyperthyroidism physical exam of skin/nails?
A
pruritus, moist skin, thinning hair, hyper pigmentation, onycholysis
18
Q
what will you find on hyperthyroidism physical exam of HEENT?
A
- lid lag and stare
- opthalmopathy/exophthalmos
- goiter or nodules
19
Q
what will you find on hyperthyroidism physical exam of cardiac?
A
tachycardia/afib
20
Q
what will you find on hyperthyroidism physical exam of neuro?
A
fine tremor and hyperreflexia
21
Q
what else will you find on physical exam for hyperthyroidism?
A
Infiltrative Dermopathy raised hyperpigmented orange skin
Thyroid acropathy from prolonged hyperthyroidism – clubbing digits
Goiter with bruit
22
Q
what is the mainstay of diagnosis for hyperthyroidism?
A
Labs!!!
23
Q
when diagnosing hyperthyroidism what will the labs show?
A
- TSH (decreased b/c a lot of T4/T3)
- elevated T3/T4
- antibodies (Anti-TPO, anti-thyrotropin receptor, thyroid-stimulating immunoglobulin)
(also decreased serum cholesterol & hypercaclcemia)
24
Q
imaging studies for hyperthyroidism?
A
Nuclear scintigraphy w/RAIU (thyroid scan)
-thyroid scan with radioactive iodine uptake
(also ultrasound + doppler & see increased flow in thyroid)
25
treatments for hyperthyroidism
symptomatic treatment (oral/IV rehydration, beta-blockers)
antithyroid drugs (thioamids)
- Methimazole
- Propylthiouracil (1st trimester in pregnancy)
*RADIOACTIVE IODINE TREATMENT*
surgery
26
who are thioamides good for?
patients with mild hyperthyroidism/small goiters who are likely to go into remission or not candidates for surgery or waiting radioactive iodine treatment
27
side effects of thioamides?
agranulocytosis
28
what is the treatment of choice for hyperthyroidism?
Radioactive iodine treatment
29
how does radioactive iodine treatment work and what's its downfall?
PO single dose
- destroys thyroid over weeks
- results in permanent hypothyroidism, requiring Levothyroxine for the rest of your life
30
when is surgery for hyperthyroidism indicated & what will it require?
Indicated for non compliant patients, patients with very lager goiters compressing structures and children
Will required lifelong Levothyroxine
31
what is thyroid storm?
very rare, bad extreme of hyperthyroidism
occurs in people with UNTREATED hyperthyroidism
brought on by a major life stress such as trauma, heart attack, or infection
32
how do you diagnose thyroid storm?
clinical (can't draw labs)
33
how does thyroid storm present?
- fever, tachycardia, HTN, neurological and GI abnormalities
- HTN may be followed by CHF that is associated with hypotension and shock
- Delirium, severe tachycardia, vomiting, diarrhea, dehydration, fever, heart failure, pulmonary edema
- High mortality rate – invariably fatal if left untreated
34
what are the main treatments for thyroid storm?
IV thiourea - prevents thyroid from producing anymore, but doesn’t effect T4/T3 that’s circulating
Iodine compound PO (Lugol's solution) - given one hr after Thiourea; blocks release and conversion of T4/T3
35
what is the most common cause of hypothyroidism in the US?
Hashimoto's
36
when does the risk of hypothyroidism increase?
increases with age (most prevalent in the elderly)
37
where are goiters commonly seen & what does a +goiter correlate with?
Goiters are commonly seen in areas where iodine deficiency is common due to diet
+ goiter, correlation with progression to papillary thyroid cancer
38
what is hypothyroidisms bad extreme?
Myxedema coma - has high mortality rate
39
what is Hashimoto's?
```
Autoimmune Thyroiditis (Hashimoto's)
e.g. Chronic Lymphocytic Thyroiditis
```
-Body attacks the thyroid and destroys it
+Antibodies is hallmark
40
what is the hallmark of Hashimoto's?
+ antibodies
41
other causes of hypothyroidism? (besides Hashimoto's)
Thyroidectomy (for hyperthyroidism, goiter, thyroid cancer)
Central Hypothyroidism HPO axis deficiency
42
what are the common symptoms of hypothyroidism?
EVERYTHING SLOWS DOWN (VS HYPERTHYROIDISM IS FAST)
- fatigue, lethargy, depression
- cold intolerance
- weight gain
- dry skin
- thinning of hair
- puffy face/eyelid
- goiter (in both hyper/hypo)
- bradycardia
- delayed reflex
43
what is the best screening test for Hashimoto's?
TSH (will be elevated b/c not producing enough T4/T3, so increasing more TSH)
44
what will T4/T3 levels be in Hashimoto's?
low T4/T3
45
what is the treatment of Hashimoto's?
Levothyroxine - take with water in the morning after overnight fasting
Levo is T4, body convert it to T3
46
why isn't T3 given instead of Levo (T4)?
b/c T3 has short half-life
47
how do you titrate Levo?
If elderly, start low and tirate up
Titrate dose up while taking certain medications that are hepatically metabolized
Titrate up as needed based on symptoms and labs (titrate every 6-8 weeks)
48
what antibodies are used for diagnosis of Hashimoto's?
antithyroid peroxidase TPO Ab & antithyroglobulin antibodies TgAb
WILL BE ELEVATED
49
what is myxedema coma?
- Severe, life-threatening hypothyroidism
- Impaired cognition, confusion coma (myxedema coma)
- Most often seen in elderly and those who have stopped taking meds
- Severe hypothermia, hypoventilation (so become hypercarbic), hyponatremia, hypoglycemia, and hypotension
- Rhabdomyolysis and acute kidney injury may occur (b/c pt not moving)
50
treatment of myxedema coma?
- Large doses of levothyroxine IV
- Hypothermic warm only with blankets, since faster warming can precipitate cardiovascular collapse
- Hypercapnia intubate and assist mechanical ventilation
- Infections must e detected and treated aggressively
- Suspected concomitant adrenal insufficiency hydrocortisone
51
what is euthyroid sick syndrome? what are the labs like? txt?
abnormal thyroid hormone levels (TSH normal, T4 low/normal, T3 low) with normal thyroid gland fxn seen with non thyroidal illness (e.g., MI, DKA, CRF, cirrhosis)
- serum cortisol elevated & antibodies negative
txt: treat the underlying cause
52
what is thyroiditis
Thyroiditis includes a group of individual disorders causing thyroidal inflammation but presenting in different ways (Hyperthyroid/Euthyroid/Hypothyroid)
53
what are causes of thyroiditis?
- Subacute Lymphocytic Thyroiditis/Silent Thyroiditis/Painless Thyroiditis (painless)
- Post-Partum Thyroiditis (painless)
- Subacute Granulomatous Thyroiditis (de Quervain’s) (painful)
- Chronic Lymphocytic thyroiditis (Hashimoto’s Thyroiditis) (painless)
- drug induced (painful)
54
what is Subacute Lymphocytic Thyroiditis/Silent Thyroiditis/Painless Thyroiditis
- Painless
- Spontaneous or triggers often autoimmune mediated and can also occur after exposure to certain drugs, such as interferon-alpha, interleukin-2, LITHIUM and tyrosine kinase inhibitors
- 50% will have antibodies
How to decipher from Graves?
-Little to no thyroid enlargement, no Graves ophthalmopathy
55
what is Post-Partum Thyroiditis?
- 2-12 months post partum
- Painless
- Usually transient
- >80% will have antibodies
Hyperthyroid will last a few weeks (before get to hypothyroid)
-Most will progress to hypothyroid state which may last few months
-Recurrence rate high 70%
56
what is Subacute Granulomatous Thyroiditis (de Quervain’s)?
- Lower grade fever
- PAINFUL
- *Viral Etiology – h/x URI with extreme neck pain*
- Painful nodule, throat dysphagia
- *overlooked because symptoms mimic pharyngitis
Must r/o infectious bacterial suppurative thyroiditis
57
what is Chronic Lymphocytic thyroiditis?
(Hashimoto's)
-NOT PAINFUL, HAVE LIFELONG HYPOTHYROID
58
what is drug induced thyroiditis?
NOT PAINFUL
Caused by:
- Amiodarone
- Lithium
- Phenytoin
- Radioactive Iodine
59
what is amiodarone thyroiditis?
- Can occur 4 months – 3 years after starting
- Clinically significant hypothyroidism occurs in about 15-20% patients
- Type 1: active production of excessive hormones due to too much free iodine
- Type 2: destructive thyroiditis which releases stored hormones
Typically resolves over several months s/p discontinuation of medication
60
how do you treat thyroiditis?
TREAT SYMPTOMS
treat with LEvothyroxine if in hypothyroid state
DO NOT treat with Thionamides (if in hyperthyroid state)
61
what is the most common malignancy of the endocrine system? & types?
Thyroid carcinoma
-death rate is low
Types: papillary, follicular, medullary, and anaplastic carcinoma
62
risk factors for thyroid carcinoma?
- History of radiation exposure
- Multiple Endocrine Neoplasia (MEN)
- Family history of thyroid cancer
- ?Hashimoto’s disease
- ?Iodine deficiency: follicular carcinoma
- Nodule dx <30 y.o and >60 y.o
63
signs & symptoms of thyroid cancer?
*Painless, palpable nodule*
(Firm non-mobile nodules suspicious for malignancy)
- Rapid growth indicates ominous sign
- Firm cervical masses highly suggestive of regional lymph node and metastasis
-Vocal cord paralysis, hoarse voice
64
what is papillary thyroid cancer?
- Most common thyroid cancer (70-90%)
- Psammoma bodies – cleaved nuclei
- Spread via lymphatics as well as hematogenously (bone, lungs)
- Slow growth
- Found early, excellent prognosis
65
what is follicular thyroid cancer?
- More common in iodine deficient regions*
| - *Tends to spread hematogenously (bone, lung, CNS)*
66
what is medullary thyroid cancer?
Associated with MEN2A and 2B
- Most common cause of mortality in MEN patients
- Some advocate for prophylactic thyroidectomy
- Calcitonin will be elevated
- Management is primarily surgical
67
what is anaplastic thyroid cancer?
- Poor differentiated (undifferentiated), aggressive, early metastasis to nodes and distant sites
- Poor prognosis (survival 6 months)
- Uncommon, inactivation of the p53 gene
68
what is the diagnostic of choice for thyroid cancer?
FINE NEEDLE ASPIRATION
-usually done ultrasound guided
(ultrasound is not diagnostic of malignancy but will provide information for possible FNA)
69
other diagnostics for thyroid cancer?
Labs:
- TSH
- serum calcitonin and CEA - medullary
- PCR gremlin mutation - medullary
Thyroid Radioiodine imaging
- Does not rule our carcinoma
- Can provide hint whether malignant or not
CT or MRI w/out contrast
- Just part of workup, not diagnostic
- Evaluate soft tissue extension of large or suspicious thyroid mass
70
thyroid cancer hot vs. cold
Terms used to describe findings on a radioactive iodine uptake scan
The hotter the nodule the less likely it is cancerous (cold nodule is concerning)
71
what is thyroid cancer treatment?
THYROIDECTOMY – GOLD STANDARD!!!
