Exam 1-- Pt 4 Thyroid Flashcards
T/F. A goiter is indicative of hyperthyroidism.
False– possible to have a goiter and be hypothyroid, euthyroid, or hyperthyroid
What is intolerance to heat, bulging eyes (exopthalmos), weight loss, increase diarrhea, and tachycardia symptoms of?
hyperthyroidism
Thyroid hormones are orally active, and consumption of thyroid tissue can cause what?
thyrotoxicosis (a form of hyperthyroidism)
- sleeplessness, nervousness, headache, fatigue, excessive sweating, weight loss
The thyroid sequesters what ion very well? Therefore, what can be used to treat hyperthyroidism and why?
iodide; use radioactive iodine b/c it can destroy secretory cells (but this may cause ind to end up hypothyroid which would then require replacement therapy)
What is an enlargement of the thyroid gland? What does the size of the gland depend on?
goiters; depends on TSH stimulation
T/F. It is possible to have a goiter and be hypothyroid, euthyroid, or hyperthyroid.
True
What is an example of a Euthyroid goiter? How does this occur?
dietary iodine deficiency (MC cause of a goiter)
- synthesis of thyroid hormones decreases and gladular T4 (T3) secretion decreases
- NOW pituitary TSH synthesis and secretion increases
- TSH stimulates growth and vascularity of thyroid
- thyroid enlarges =goiter
What is an example of a hyperthyroid goiter?
- Grave’s Disease
2. Thyroid Adenoma (tumor)
Describe how a goiter occurs in Grave’s Disease.
- thyroid stimulated by abnormal antibodies that form against the TSH receptor (known as thyroid-stimulating immunoglobulins–TSIs)
- gland hypertrophies (goiter)
- TSIs mimics TSH and stimulates synthesis and secretion of thyroid hormones (hyperthyroid)
T/F. TSIs (thyroid-stimulating immunoglobulins) have a 12x lesser effect than TSH.
False– TSIs have a 12x longer stimulating effect over TSH
therefore high thyroid hormone levels inhibits TSH formation by anterior pituitary and therefore TSH levels are decreased
Describe how a goiter occurs from a Thyroid Adenoma.
secretes large quantities of thyroid hormone
- rest of thyroid is inhibited due to negative feedback inhibition of TSH from the anterior pituitary
What does iodine deficiency beginning in utero result in?
endemic cretinism
What is Cretinism?
- caused by extreme hypothyroidism during fetal life, infancy, or childhood
- loose term applied to all forms of hypothyroidism beginning before or at birth
- characterized by failure of body growth and intellectual development disorder
In Cretinism, is skeletal growth or soft tissue growth more inhibited?
skeletal growth
What is the treatment for Cretinism?
Tx with iodine or thyroxine
- sooner is better than later to prevent intellectual development disorder
What is an autoimmune disorder that destroys the thyroid gland? What precedes it?
Hashimoto’s disease (AKA chronic lymphocytic thyroiditis); preceded by thyroiditis (inflammation)
overtime goiter may develop
What is the MC cause of hypothyroidism in the US?
Hashimoto’s Disease (aka chronic lymphocytic thyroiditis)
What is muscle stiffness/sluggishness, constipation, decrease hair growth, intolerance to cold all characteristics of?
hypothyroidism
What is 3,3’,5’-triiodothyronine?
reverse T3 (rT3) which is inactive (recall--T3 = 3,3',5 triiodothyronine)
What produces rT3?
Deiodinase type I and type III
What ratio can be looked at for diagnosis of tissue cell hypothyroidism?
free T3 vs reverse T3 ratio
What can block the pathway to produce T3 and instead produce rT3?
stressssssss
What antithyroid substance decreases iodide trapping by competitive inhibition and decreases iodination of thyroglobulin?
Thiocyanate
- this will therefore decrease thyroid hormone production
What is the end results of Thiocyanate?
decreases thyroid hormone production
What antithyroid substance decreases thyroid hormone function by blocking peroxidase enzyme? What is the affect?
Propylthiouracil
therefore increasing TSH and could lead to a goiter
What affect do high blood concentrations of inorganic iodides have?
- inhibit most aspects of thyroid function
- frequently given 2-3 weeks prior to removal of thyroid to minimize bleeding from the surgery
What is the term for severe hypothyroidism during fetal development or early childhood associated with intellectual development disorder?
Cretinism
What is the term for hyperthryoid Exophthalmos, lid lag, upper lid retraction, extraocular muscle weakness..etc?
Graves Disease
What is the term for acute inflammation of the thyroid (likely the result of a viral inf.)?
Subacute Thyroiditis
What is the term for an autoimmune disorder that destroys the thyroid in adults?
Hashimoto’s Thyroiditis
What is the term for when the tissue is exposed to excessive amounts of thyroid hormones? What is the most prevalent form?
Thyrotoxicosis
Graves Disease is most prevalent form
What is the term for generalized nonpitting edema seen with hypothyroidism?
Myxedema
there is accumulation of GAGs in interstitial spaces–> therefore retains fluid
