Term
| Which is the active form, T3 or T4? |
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Definition
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Term
| TSH acts to increase synthesis and release of _____ from the thyroid. |
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Definition
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Term
| T4 and T3 have a negative feedback on what trophic hormone/s |
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Definition
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Term
How is iodine trapped within the follicular cell?
Where and on what molecule is T4 synthesized?
what is organification? |
|
Definition
Thyroid peroxidase i-->i2
colloid, on thyroglobulin
addition of tyrosine and I2 onto thyroglobulin? |
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Term
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Definition
|
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Term
| thyroid binding globulin vs thryroglobulin |
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Definition
| first is the carrier protein in bloodstream, second is the scaffold in which t4 is synthesized |
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Term
| what are the other carrier proteins of T4 and T3 besides thyroid binding globulin? |
|
Definition
albumin
transtheyretin (thyroid-binding pre albumin) |
|
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Term
decreased TBG has what effects on T4, T3RU,and Free T4 levels?
increased TBG? |
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Definition
decrease, increase, normal
Increase, decrease, normal |
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Term
| what are the functions of thyroid hormone? |
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Definition
increase oxygen and heat production (increase basal metabolic rate)
improves cardiac contractility (increases cardiac output and heart rate)
increases B-adrenergic receptor for catecholamine sensitivity
stimulates gut motility
increases erythropoietin
increases bone turnover
increases prtein turnover and loss of muscle tissue
increases cholesterol degradation
increases metabolic turnover of many hormones and drugs |
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Term
| Hashimoto's thyroiditis commonly has an antibody to this enzyme ____ |
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Definition
| thyroid peroxidase (converts I to I2) |
|
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Term
| increasing protein concentrations may indicate hypo or hyper thyroidism? |
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Definition
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Term
| best way to measure T3 and T4 levels |
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Definition
| measure free instead of total hormone level |
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Term
assuming normal tbg levels, what is the diagnosis for a patient with an increase in t3ru?
a decrease in t3ru? |
|
Definition
hyperthyroidism (more of the spots on TBG are bound by endogenous t3)
hypothyroidism (more of the spots are available on TBG to bind t3*) |
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Term
| differences between 123-I and 131-I |
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Definition
123I has low energy gamma rays, short half-life, and superior for imaging studies
131I has multi-spectrum high energy gamma rays, beta particles do damage, longer half life, used to destroy thyroid tissue |
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Term
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Definition
| paradoxically cause primary hypothyroidism |
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Term
primary hypothyroidism:
tsh levels:
t4 and t3:
raioiodine uptake: |
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Definition
tsh elevated
t4 and t3 low
radio iodine can be any range |
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Term
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Definition
| untreated congenital hypothyroidism (often because of a lack of iodine in nutrition) |
|
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Term
| what are some of the symptoms of hypothyroidism? |
|
Definition
fatigue
weight gain
cold intolerance
constipation
menstrual irregularities
muscle cramps
slowed mentation
dry, rough skin
periorbital edema
delayed muscle stretch reflexes
carotenemia
edema |
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Term
| what should you do with a patient that is just beginning to show symptoms of primary hypothyroidism? |
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Definition
| treatment is benign if monitored properly |
|
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Term
euthyroid sick syndrome is common in what patients?
what are the T4/T3 levels?
TSH levels?
Reverse T3 levels?
treatment? |
|
Definition
occurs in patients with acute or chronic medical illness
low t4/t3 due to inhibitors of protein binding (low serum proteins in many chronically ill patients)
TSH is normal
T4 is preferentially diodinated to reverse T3 so these levels will be elevated
DO NOT TREAT WITH THYROID HORMONE |
|
|
Term
What is a myxedema coma?
What are the symptoms? |
|
Definition
End stage of untreated hypo thyroidism
Progressive weakness, hypothermia, hypoventilation, stupor, hyponatremia, cv failure
low T3 and high TSH levels, require emergent treatment |
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Term
| What is the treatment of choice for thyroid hormone replacement? |
|
Definition
levothyroxine (synthetic)
desiccated thyroid made from animal thyroids is less advised, contains t3 that has short half-life |
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Term
|
Definition
| hyperthyroidism due to throid tissue in ovary |
|
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Term
| an increase of chorionic gonadotropin (b-HCG) causes what |
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Definition
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Term
what is graves disease?
What are the two antibodies that cause it? |
|
Definition
autoimmune disorder caused by antibody-mediated stimulation of thyroid, independent of TSH
thyroid stimulating immunoglobulin
thyrotropin blocking antibody (TRAb) |
|
|
Term
Are men or woman more likely to have grave's disease?
What is a distinguishing feature of grave's disease? |
|
Definition
7 times more common in woman
exophthalmos due to increased protein deposition behind eye |
|
|
Term
| what is the clinical triad of graves disease? |
|
Definition
hyper vascular goiter
exophthalmos
pretrial myxedema |
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Term
| A woman present with exopthalmos, but is euthyroid. Is this possible? |
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Definition
|
|
Term
| What are the TSH levels in hyperthyroidism? |
|
Definition
| always suppressed except in the rare case of inappropriate TSH secretion |
|
|
Term
| What is disporportately high in graves disease? |
|
Definition
|
|
Term
| what are some treatment options for graves disease? |
|
Definition
antithyroid drugs
radioactive iodine
surgery
b blockade (propranolol)
iodide to paradoxically inhibit hormone release |
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|
Term
| Thianamides is a class of antithyroid drugs that include... |
|
Definition
| PUT and Tapazole, ineffective for hormone already synthesized...PUT also inhibits conversion of T4 to T3 |
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Term
| What is the issue with antithyroid drugs? |
|
Definition
relatively high risk of side effects rash, arthralgias common
leukopenia, liver issues more uncommon |
|
|
Term
| Is it recommended to use antithyroid drugs for an extended amount of time? |
|
Definition
| No, treat for 6 months to a year and then withdrawal...may have to treat with I131 |
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Term
| Why would hyperthyroidism be treated surgically instead of with I131? |
|
Definition
pregnant woman
must pretest with thionamides and propranolo |
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|
Term
| Shoulder pad sign is indicative of |
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Definition
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Term
| Does T4 or T3 cross the placenta well? What about TSIg |
|
Definition
no
yes (can cause a temporary neonatal graves disease) breathing is the greatest issue |
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|
Term
|
Definition
autonomously functioning thyroid nodule not responsive to TSH and not antibody-mediated
milder hyperthyroidism than graves
typical in older patients |
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|
Term
| What is destructive thyroiditis? |
|
Definition
causes hyperthyroidism by release of preformed hormone, low TSH and low radio iodine uptake
thyroglobulin levels may be elevated |
|
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Term
| What occurs to the T4 levels over a course of time with destructive thyroiditis? |
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Definition
| Will peak and then drop, and slowly rise again |
|
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Term
| what is thyrotoxicosis factitia? How can you distinguish this from destructive thyroiditis? |
|
Definition
ingestion of excess thyroid hormone
RAI uptake low (iodine)
thyroglobulin is low as opposed to destructive thyroiditis |
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|
Term
| what is apathetic hyperthyroidism? |
|
Definition
elderly may have blunted response to thyroid hormone (ie. high t3/t4 with minimal symptoms)
may appear paradoxically depressed! |
|
|
Term
| when do you treat subclinical hyperthyroidism? |
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Definition
| hold off because treatment is potentially toxic, unlike subclinical hypothyroidism |
|
|
Term
| What are the symptoms of a thyrotixic crisis (storm) that is an end stage of untreated hyperthyroidism |
|
Definition
fever
delirium
diarrhea
CV
mortality high if untreated |
|
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Term
| What would you give to a patient that has a thyrotoxic crisis? |
|
Definition
PTU is preferred because it converts t4-t3
beta blockers (propranolol)
iodide |
|
|
Term
|
Definition
common, especially in older women
most benign |
|
|
Term
| what are the risk factors for having a malignant thyroid nodule? |
|
Definition
solitary nodule
male patient (nodules more common in woman)
rapid growth
cold nodule (15% malignant) |
|
|
Term
| what is meant by cold nodule? warm nodule? hot nodule? |
|
Definition
cold-does not take up radio iodine tracer
warm-same uptake as normal tissue
hot-takes up more tracer, rarely benign
Conclusion: minimally useful in evaluating malignancy |
|
|
Term
| what is the most common type of thyroid cancer? |
|
Definition
|
|
Term
|
Definition
| often as occult micro carcinomas that spreads slowly, to local lymph nodes first and patient survival is usually good, even with metastatic disease |
|
|
Term
|
Definition
| more aggressive than papillary, most patients still do pretty well |
|
|
Term
| what are classified as epithelial thyroid cancers? |
|
Definition
| papillary and follicular carcinomas |
|
|
Term
| what is the treatment for papillary and follicular carcinoma? |
|
Definition
| total thyroidectomy followed by I 131 remnant ablation |
|
|
Term
| medullary thyroid carcinoma |
|
Definition
rare, not a disorder of thyroid epithelial cells so thyroglobulin is not a useful marker
disorder of parafollicular cells, calcitonin is a marker |
|
|
Term
| what is the treatment for medullary thyroid carcinoma? |
|
Definition
| total thyroidectomy, not generally responsive to I 131, must also screen for pheochromaocytoma, hyperparathyroidism |
|
|
Term
| anapestic thyroid carcinoma |
|
Definition
| palliative care only, patients will die |
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