Term
| Thyroid hormone synthesis - see slide "1" |
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Definition
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Term
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Definition
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Term
| types of deiodinases and significance |
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Definition
Types I, II, III
they're all over body, so don't need T3 bc T4 can be converted throughout body
**no clinical usefullness to measuring T3 |
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Term
| list some of thyroid lab tests |
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Definition
TSH, T3 - triiodothyronine,
T4-thyroxine
free hormone levels, T3-resin uptake
antibodies, thyroglobulin |
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Term
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Definition
1st and most impt test to be done when screening for abnormal thyroid
**do not use in hypopituitarism pts |
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Term
| pregnancy effect on thyroid hormones |
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Definition
| see increased total thyroid hormone, but normal level free hormone |
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Term
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Definition
| most common test for free hormone level |
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Term
T3 resin uptake (protein binding assessment)
1. increased when
2. decreased when |
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Definition
1. increased when there is reductioni n protein binding sites-->pregnancy and situations where women are taking estrogen
2. decreased with increased protein binding sites |
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Term
| thyroid stimulating immunoglobulin (TSI) and thyroid binding inhibitory immunoglobulin seen in |
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Definition
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Term
| thyroglobulin increased in |
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Definition
all with thyrotoxicosis except thyrotoxicosis factitia
**used for following thyroid Ca |
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Term
nuclear scanning of thyroid fx: increased uptake in...
decreased uptake in.. |
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Definition
increased uptake in Graves' disease; toxic nodules/multinodular goiter
decreased uptake (when inflamed) in thyroiditis |
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Term
| 2 things interfering w/nuclear interpretation |
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Definition
amiodarone bc about 40% iodine in molecule
high iodine diet |
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Term
| most common cause primary hypothyroidism |
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Definition
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Term
Hashimoto's Thyroiditis
1. disease type
2. process |
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Definition
1. gradual autoimmune process (anti-TPO, Anti-Tg, TBII)
2. compensation period, TSH rises to keep thyroid hormone levels normal |
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Term
| Effects of hypothyroidism (6 categories) |
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Definition
skin - nail growth decreased, dry skin
hair - brittle, thinning of outer 1/3 eyebrows
cardio - decreased contractility and pulse rate
pulmonary - impaired resp. m. fx
genitourinary - decreased libido, oligo/amenorrhea
neuromuscular - carpal tunnel, muscle stiffness/cramps/pain |
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Term
| LAB for primary and secondary hypothyroidism |
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Definition
primary - TSH increased; T4, T3, T3RU decreased
secondary - TSH LOW/normal; T3/T4 low |
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Term
Choosing the correct exam:
1. high TSH, low throid hormones
2. low TSH, low thyroid hormones |
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Definition
1. high TSH, low thyroid hormones
-no radiologic exam
-can check antibodies
2. low TSH, low thyroid hormones
-check other pituitary fx
-MRI pituitary |
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Term
| DOC for TX hypothyroidism |
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Definition
| levothyroxine (synthetic T4) |
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Term
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Definition
7 days - so steady state not reached for 4-5 wks
**see case 1 |
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Term
Myxedema coma
1. mortality
2. clinical |
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Definition
1. high mortality rate - age of pt and underlying condition impt
2. decrease level of consciousness, hypothermia, seizures
**look for underlying cause |
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Term
| endocrine axiom 5: in any pt presenting w/an endocrine emergency, look for precipitating cause |
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Definition
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Term
Myxedema Coma
3. causes
4. Tx (2) |
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Definition
3. pneumonia, MI/CHF, stroke, etc.
4. Tx - **always check adrenal reserve before tx
-levothyroxine
-supportive care-->ventilator, IV fluids, etc.
**see clinical case 2 |
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Term
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Definition
hyperactivity, irritability
heat intolerance, sweating, fatigue, palpitations
tachycardia, tremor, goiter |
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Term
| thyrotoxicosis definition |
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Definition
| too much TH in blood-->can have it w/o hyperthyroidism |
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Term
| 2 causes primary hyperthyroidism |
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Definition
Graves' disease
drug: iodine excess |
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Term
| 2 causes secondary hyperthyroidism |
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Definition
TSH secreting pituitary adenoma
gestational - when hCG so high that pt develops a mild thyrotoxicosis |
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Term
| most common cause thyrotoxicosis |
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Definition
| Graves' disease (more common in women) |
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Term
| 2 major presentations of Grave's disease |
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Definition
dermopathy
orbitopathy - diplopia, visual loss, etc. |
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Term
| subacute thyroiditis clinical (2) |
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Definition
may be preceded by viral infection/URI
hypothyroid in second phase
**anytime there's a low TSH, do a radioiodine scan |
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Term
| LAB for primary hyperthyroidism (2) |
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Definition
TSH decreased/suppressed
T4, T3, T3RU increased |
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Term
1. secondary hyperthyroidism LAB (2)
2. subacute thyroiditis lab |
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Definition
1. TSH normal/increased
-increased alpha-subunit
2. suppressed TSH, increased T4, high sed rate |
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Term
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Definition
| TSH suppressed; either T3, T4, or both increased |
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Term
CHOOSING THE CORRECT EXAM
1. low TSH, high thyroid hormones |
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Definition
nuclear scan - uptake increased in Grave's and decreased in subactute thyroiditis or thyrotoxicosis factitia
TSI or TBII, thyroblobulin, or sed rate depending upon circumstances
-TSI elevated in Graves'
-thyroglobulin decreased in thyrotoxicosis factitia
-sed rate increased in subacute thyroiditis |
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Term
| 2. high TSH, high thyroid hormones |
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Definition
| MRI, alpha-subunit, referral |
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Term
| 3 principal therapies for TX hyperthyroidism |
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Definition
1. antithyroid drugs
-methimazole for non-pregnant (avoid 1st trimester)
-propylthiouracil (PTU) for 1st trimester
2. subtotal thyroidectomy
3. radioactive iodine- can't give to breastfeeding women |
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Term
| 3 adjunctive therapies for hyperthyroidism |
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Definition
iodine, beta blockers, lithium
**see clinical case 3 |
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Term
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Definition
rare endocrine emergency with mortality 10-75%
look for precipitating factor (8usually unknown) |
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Term
| endocrine axiom 5: in any pt presenting w/an endocrine emergency, look for precipitating cause |
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Definition
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Term
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Definition
fever out of proportion to infection
tachycardia out of proportion to fever/arrhythmias
BP, shock, GI, CNS |
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Term
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Definition
thyroid hormones don't differ form uncomplicated thyrotoxicosis
important to check LFT (increased) d/t hepating congestion or dysfx |
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Term
| Pharmacologic Tx Thyroid storm (6) |
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Definition
propylthiouracil
SSKI or Lugols solution
propranolol to slow down HR
dexamethasone to decrease conversion T4 to T3
aggressive replacement volume deficit - IV fluids, dextrose
TX underlying cause
**think about definitive tx when pt is "cooled down"
**see clinical case 4 |
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Term
| MISCELLANEOUS THYROID DISORDERS |
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Definition
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Term
| binding abnormalities - TBG levels |
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Definition
decreased TBG will decrease total hormone levels - androgens, nephrotic syndrome
increased TBG will increase total hormone levels - acute liver disease, HIV, estrogen |
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Term
| binding abnormalities seen with... |
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Definition
"female things"
-TBG increased w/estrogen and estrogen-like comopunds; total hormone levels increased; pt euthyroid |
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Term
euthyroid sick
1. due to
2. most common
3. low T4 and T3 = |
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Definition
1. d/t cytokine release
2. most common is decreased total and free T3-->correlates w/severity of illness
**low T4 and T3 - poor prognosis
**do NOT need thyroid hormone - will actually increase mortality |
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Term
Amiodarone
1. most impt characteristic
2. 2 things it causes
3 changes seen |
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Definition
1. 39% iodine by wt
2. causes hypo or hyperthyroidism
3. acute transient changes: decrease T4, increase T4 w/decrease T3, TSH rise |
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Term
THYROID NODULES
frequency of thyroid nodules increases with... |
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Definition
| age, ionizing radiation in childhood, iodine deficient areas |
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Term
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Definition
5-15% palpable nodules malignant
clinically silent cancer
easy to treat |
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Term
| 3 factors favoring benign nodule |
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Definition
FHx nodule/goiter
FHx autoimmune thyroid disease
hypo/hyperthyroidism |
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Term
| non-palpable thyroid nodules found on imaging |
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Definition
incidentalomas
**palpable lesions may not always be found on imaging |
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Term
| 3 risk factors for malignancy |
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Definition
extremes of age (<20, >70)
males 2:1
hx irradiation |
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Term
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Definition
nodules >1 cm usually palpable
50% nodules on ultrasound not detected clinically |
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Term
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Definition
TSH
thyroid antibodies - anti-microsomal/anti-thyroid peroxidase, anti-thyroglobulin, TRAb
**anti-microsomal/anti-thyroid peroxidase and anti-thyroglobulin helpful to dx Hashimoto's |
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Term
| LAB - only test calcitonin in pts... |
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Definition
| with FHx mdeullary cancer (rare) |
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Term
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Definition
| does not determine whether a lesion is benign or malignant; ultrasound helpful to categorize what it looks like |
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Term
| the fastest, easiest, and most cost-effective method for assessing thyroid nodules |
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Definition
| fine-need aspiration biopsy |
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Term
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Definition
levothyroxine if hypothyroid
surgery if local symptoms/cosmetic issues |
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Term
| most common type of thyroid cancer |
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Definition
| follicular derived, differentiated papillary cancer |
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Term
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Definition
SURGERY - initial therapy
high dose radioactive iodine, suppressive levothyroxine, chemo, external beam radiation |
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Term
Thyroid cancer follow-up
1. TSH
2. thyroglobulin
3. medullary thyroid cancer |
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Definition
1. TSH should be low normal or just under normal while on levothyroxine
2. thyroglobulin tumor marker - TSH stimulated Tg should be <.2 if no residual cancer
3. calcitonin and CT scan for medullary thyroid cancer (Sx disorder) |
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Term
| thyroid cancer follow-up screening (2) |
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Definition
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Term
thyrogen
1. what is it
2. role |
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Definition
1. recombinant human TSH
2. used to prep pts for tx and follow-up scanning rather than making them hypothyroid |
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