Thyroid Disorders - Cryar Flashcards
What are examples of thyroid disorders based on abnormal function?
thyrotoxicosis
hypothyroidism
What are examples of thyroid disorders based on abnormal structure?
diffuse goiter
nodular goiter (solitary nodule or multi)
atrophy
What are the most important and valid thyroid tests?
TSH Free Thyroxine (FT4)
What are the thyroid antibody tests testing for and for which diseases?
1) anitmicrosmal and antithyroglobulin - highly positive in chronic lymphocytic thyroiditis
2) thyroid stimulating Ig (TSIG) - marker for graves disease
When is thyroglobulin test high and when is it low?
low - exogenous thyroid ingestion
high - thyrotoxicosis
What is the main marker for recurrent thyroid cancer?
thyroglobulin tests
Which nuclear thyroid tests are there?
1) radioactive iodine (I131) - scan for configuration or uptake for function
2) technetium scan - for configuration
Why is an ultrasound good for seeing the thyroid?
it can see nodules < 1mm
Why do we test TSH and not actual thyroid hormone levels for function?
bc a patient can be hyperthyroid or hypothyroid and have “normal” thyroid hormone levels - T3/T4 are very sensitive to proteins and thyroid binding globulin (pregnancy, oral contraceptives, low albumin)
TSH is not affected by TBG or proteins
Why is TSH a sensitive test?
1) changes log rhythmically in response to change in thyroid hormone
2) can be supressed or elevated while the hormone is still in the normal range
What is subclinical thyroid disease?
patients with normal thyroid hormone levels and abnormal TSH - subclinical referring to the fact that the symptoms are not evident to the doctor
What can subclinical thyroid disease result in?
atrial fibrilation
osteoperosis
What are the etiologies of thryotoxicosis?
Graves Disease Toxic nodular goiter toxic nodule thyroiditis exogenous
What are the signs and symptoms of thyrotoxicosis?
nervousness heat intolerance palpitations tremulousness weight loss weakness diarrhea enlarged thyroid ophthalmopathy warm, smooth skin fine tremor brisk reflexes proximal weakness tachycardia
What is Graves disease?
Hyperthyroidism - due to immunoglobulin stimulation of the TSH receptor and produces a diffuse goiter
What are some complications of graves disease?
1) ophthalopathy - an inflammatory condition of the periorbital tissue
2) pretibial myxedema
How do you diagnos Graves disease?
1) clinical features - goiter, ophthalmopathy, Symptoms
2) thyrotoxicosis on lab data - undetectable TSH and elevated T4
3) diffuse, elevated I131 uptake
4) positive TSIG
What are the consequences of thyroid associated ophthalmopathy?
1) due to thyrotoxicosis of any etiology - lid lag and widened palpebral fissure
2) inflammatory- conjuctival and periorbital edema and red eye
3) infiltrative - proptosis (double vision), lid retraction, compromise vascular supple to optic nerve
What nerves are affected in Graves disease ophthalmopathy?
medial and inferior rectus - problems looking up/out and laterally
What are the 3 treatment options for Graves disease?
1) radioactive Iodine (I131)
2) surgery
3) antithyroid medications
How does I131 treat Graves?
the thyroid slowly stops working. Its painless and you get gradual development of hypothyroid
There is a temporary risk or rise in T4
What is the benefit to using surgery to treat Graves and who should get it?
this option is for really sick and frail patients. It is good for QUICK resolution. You get hypothyroidism right away. (risk of hypoparathyroidism or recurrent laryngeal nerve damage)
When toxic nodular goiter usually occur?
with known long-standing nodular goiter
What is seen with I131 uptake on patients with toxic nodular goiter?
patchy uptake of I131
How is toxic nodular goiter treated?
1) surgery
2) I131 - less responsive to this than Graves disease
What is toxic nodule?
solitary autonomous nodule suppressing the remaining thyroid tissue
How is toxic nodule treated?
1) I131
2) surgery
When is thyrotoxicosis usually seen and how is it treated?
It is secondary to thyroiditis
self-limited illness requiring symptomatic treatment
What can thyrotoxicosis be indistinguishable from clinically?
Graves disease
How can laboratory tests distinguish throtoxicosis from Graves disease?
on lab work thyrotoxicosis shows low I131 uptake and TSH = 0
What are the 3 types of thyroiditis?
1) acute (bacterial, fungal)
2) subacute granulomatous (de Quervain’s)
3) chronic lymphocytic (hashimoto’s)
What is the three phase response of chronic throiditis?
1) thyrotoxicosis
2) hypothyroidism
3) recovery or permanent hypothyroidism
What is post-partum thyroiditis?
a variant of Hashimoto’s
What is the clinical course of post-partum thyroiditis?
1) hyperthyroidism (1-4 months after delivery lasting 2-8 weeks)
2) hypothyroidism (lasts 2-8 weeks)
3) recovery
What are the clinical findings in subacute granulomatous thyroiditis or de Quervain’s?
1) PAINFUL
2) preceded or associated with fever
3) elevated ESR
4) may have thyrotoxicosis with low I131 uptake
How do you treat subacute granulomatous thyroiditis or de Quervain’s?
Symptomatic
1) asprin or NSAIDs
2) propanolol
3) maybe steroids
What is the typical outcome of de Quervain’s?
usually self limited
8-12 weeks
What is another name for chronic lymphocytic thyroditis?
Hashimotos
What are complications of Hashimotos?
1) hypothyroidism
2) thyrotoxicosis
What is seen clinically in exogenous thyrotoxicosis?
1) suppressed TSH and elevated FTI (free thyroid index)
2) normal or small thyroid
3) low thyroglobulin
4) low I131 uptake
What are the types of euthyroid goiter?
1) endemic (areas of iodine deficiency)
2) sporadic (hereditary)
3) nodular
4) diffuse
What are some clinical features of hypothyroidism?
1) lethargy and fatigue, bradycardia, thin hair
2) dementia, irregular menses
3) cold intolerance, dry coarse skin, pallor
4) weight gain, thick tongue
5) hoarseness, paresthesis
6) delayed relaxation of reflexes
How is primary hypothyroidism diagnosed?
with elevated TSH
How is secondary hypothyroidism diagnosed?
1) low T3/T4
2) inappropriately low TSH (normally the TSH should be elevated if the FTI is low)
How do you treat hypothyroidism?
initiation of thyroxine
what are some cautions to be aware of with initiation of thyroxine for hypothyroidism?
1) caution in elderly or those who have compensated heart disease
2) does the patient have schmidt syndrome? (autoimmune polyendocrine disorder)
Why do we replace with T4 and not T3?
the body converts T4 to T3 in the exact amount the body needs
Why is a thyroid scan usually not helpful for cancer?
thyroid cancer is usually a “cold nodule”
What are the types of thyroid carcinomas?
1) papillary - most common and most indolent
2) follicular - less common and more aggressive
3) anaplastic - most aggressive of all cancers
4) medullary - sporadic or familial (MEN II)
