Pharm
Why was Iris given atenolol?
Atenolol is a selective B1-blocker given for symptomatic control of thyrotoxicosis
- Can help decrease HR, CO, and reduce tremors
What connects the right and left lobe of the thyroid?
Isthmus
Hyperthyroidism: syndrome of excessive thyroid function
Thyrotoxicosis: state of excess thyroid hormone (could be due to ectopic production or exogenous source)
What is the most common cause of hypothyroidism (when iodine is sufficient)?
Hashimoto thyroiditis - autoimmune destruction of thyroid gland
- production of anti-thyroglobulin and anti-thyroid peroxidase
- associated with HLA-DR3 and HLA-DR5
How does I- get enter follicular epithelial cells?
Enters through Na+/I- cotransport
- activity of pump is regulated by I- levels
- inhibited by thiocyanate & perchlorate
Can methimazole or propylthiouracil be used in pregnancy?
Propylthiouracil should be used in the 1st trimester of pregnancy (methimazole can cross the placental barrier --> teratogenic effects)
**Switch back to methimazole during 2nd and 3rd trimester due to risk of PTU-induced hepatotoxicity.
Thyroid peroxidase is involved in 3 reactions for thyroid hormone synthesis.
1) Oxidization (I- to I2)
2) Organification (I2 combines with thyroglobulin)
- formation of monoiodotyrosine (MIT) and diiodotyrosine (DIT)
3) Coupling (2 molecules of DIT or 1 of DIT + 1 of MIT)
What are 3 options for treatment of Graves' disease?
1) Thionamide therapy (methimazole, PTU)
2) Radioactive Iodine (RAI) therapy
3) Thyroidectomy
Congenital hypothyroidism is called?
And associated with the 6 P's?
Cretinism
Pot-bellied, Pale, Puffy-faced child with Protruding umbilicus, Protuberant tongue, Poor brain development
Sjogren's Syndrome is an autoimmune disease that commonly affects?
What type of hypersensitivity?
Exocrine glands -- primarily salivary and lacrimal glands
Type IV hypersensitivity reaction (T-cell mediated)
Levothyroxine is a synthetic form of? Used in hypo- or hyperthyroidism?
Synthetic form of thyroxine (T4) used in hypothyroidism
Thyroid deiodinase vs. 5-deiodinase
Thyroid deiodinase: deiodinases MIT and DIT to recycle I- and tyrosine
5-deiodinase: deiodinases T4 (inactive) to T3 (active)
- also converts to rT3 (inactive)
What is thyroid storm?
Complication of hyperthyroidism when thyrotoxicosis goes untreated and is exacerbated by acute stress
- presents with agitation, delirium, fever, hyperglycemia, coma, tachycardia with possible arrhythmia
- may cause death
- treat with 4 P's (Propranolol, PTU, Prednisolone, Potassium iodide)
What is myxedema?
Accumuation of glycosaminoglycans and hyaluronic acid within reticular layer of dermis
- GAGs pull water into tissue causing nonpitting edema
Calcitonin is secreted by? And acts to?
Secreted by parafollicular "C" cells
Inhibits activity of osteoclasts to decrease bone resorption and Ca2+ levels (works to counteract PTH)
What is teprotumumab indicated for and how does it work?
Used to treat Graves' ophthalmopathy
MOA: binds to IGF-1 receptor and prevents stimulatory effects of auto-antibodies (TSI)
- prevents the release of inflammatory molecules and GAGs into orbital tissue
How is the hypothalamus-pituitary-thyroid axis involved in thyroid hormone secretion?
What are some symptoms of hyperthyroidism?
What are Graves' specific symptoms?
Increased BMR due to increased Na+/K+ ATPase activity: weight loss, heat intolerance, sweating
Increased sympathetic activity: tachycardia, arrhythmia, high blood pressure (increase beta-adrenergic activity), nervousness
Graves' specific: pretibial and periorbital myxedema, Graves' exophthalmos
What are some symptoms associated with hypothyroidism?
Decrease in BMR: dry skin, increased cholesterol, cold intolerance, slowed cognition
Decrease in sympathetic activity: decreased sweating, constipation, bradycardia
When are I-131 and I-123 used?
I-131: used in radioactive iodine ablation as treatment (emits gamma and beta radiation)
I-123: used in thyroid scan and uptake (emits only gamma radiation)
*Low doses of I-131 may be used in scan
What is the MOA of methimazole and propylthiouracil? Common adverse effects? Which is preferred?
Methimazole: inhibits thyroid peroxidase
PTU: inhibits thyroid peroxidase AND 5'-deiodinase
Common adverse effects: agranulocytosis, aplastic anemia, liver damage (PTU), ANCA-associated vasculitis (PTU)
Methimazole is usually preferred due to lesser side effects, longer half-life, faster onset.
Main function of thyroid hormone (7 B's)
Brain maturation, Bone growth, B1-adrenergic effects, Basal metabolic rate, Blood sugar, Break down of lipids, stimulates surfactant synthesis in Babies
Explain the pathogenesis of Graves' disease.
1) B cells produce thyroid-stimulating IgG antibodies that act like TSH
2) Binds to TSH receptors on follicular cells
3) thyroid hyperplasia + increased function
4) increased synthesis of thyroid hormone + diffuse goiter
What levels of TSH and free T4/T3 would you expect in primary, secondary, and tertiary hypothyroidism?
Primary: increase in TSH; decrease in free T4/T3
Secondary: decrease in TSH; decrease in free T4/T3
Tertiary: decrease in TSH; decrease in free T4/T3
What is the Wolff-Chaikoff effect?
Jod-Basedow phenomenon?
Wolff-Chaikoff effect: autoregulatory mechanism that inhibits too much organification of I- in the presence of excess iodine
Jod-Basedow phenomenon: seen in patients w/ iodine deficiency who receive a sudden surge in iodine and produce excess thyroid hormone