Endocrine Flashcards
What is the histologic hallmark of medullary thyroid cancer?
Nets of polygonal cells with Congo red-positive deposits (amyloid deposits). Derived from parafollicular calcitonin-secreting C cells.
What are the lipid-soluble hormones?
Steroids (e.g. estrogen, aldosterone, cortisol), thyroid hormone, and fat-soluble vitamins. They have intracellular receptors which have a zinc-finger motif (zinc atom linked via cysteine and histidine residues) which allows for the receptor to bind DNA and alter the activity of target genes.
What bone changes will be seen in a patient with hyperparathyroidism?
Subperiosteal resorption with cystic degeneration. Results in elevated serum calcium and low serum phosphate.
Which hormones bind to Gs receptor proteins?
TSH, glucagon, and PTH
How do you screen for type 1 diabetes?
Fasting glucose (>126 mg/dL), Hb A1c (>6.5%) or a random glucose (>200 mg/dL). Note that an oral glucose tolerance test is not the preferred screening for this. An oral glucose tolerance test is used to screen for gestational diabetes and cystic fibrosis-related diabetes.
What does the histology of Hashiomoto thyroiditis show?
Intense lymphocytic infiltrate, often with germinal centers.
What are the histologic hallmarks of Riedel thyroiditis?
Extensive fibrosis of the thyroid gland that extends to surrounding structures. The fibrotic thyroid gland is typically hard and fixed to surrounding structures, resembling malignancy.
What does subacute (de Quervain, granulomatous) thyroiditis look like on histology?
Characterized by a mixed cellular infiltrate with occasional multinucleated giant cells. Typically presents after a viral illness with a painful, tender thyroid.
What type of receptor does glucagon bind to?
Gs (activates adenylate cyclase which increases cAMP which activates protein kinase A)
What is the first line treatment for infiltrative ophthalmopathy caused by Grave’s disease?
Glucocorticoids. Severe ophthalmopathy is characterized by worsening diplopia, extraocular muscle involvement, and exposure keratitis.
What are the actions of somatostatin, and what are the complications associated with somatostatinomas (rare pancreatic islet cell tumor)?
It decreases the secretion of secretin, cholecystokinin, glucagon, insulin, and gastrin. It is secreted from pancreatic delta cells. Patients with somatostatinomas present with hyper or hypoglycemia, steatorrhea, and gallbladder stones. Gallbladder stones form because of poor gallbladder contractility, which is secondary to inhibition of cholecystokinin release.
What are signs of congenital hypothyroidism?
Signs may include lethargy, hoarse cry, poor feeding, constipation, jaundice, dry skin, large fontanelle, umbilical hernia, hypotonia, and protruding tongue. Infants are at risk for irreversible intellectual disability.
Treatment with levothyroxine by age 2 weeks can normalize cognitive and physical development.
Most common etiology is thyroid dysgenesis.
True or false: elevated serum free fatty acid levels contributes to insulin resistance
True. FFAs impair insulin-dependent glucose uptake and increase hepatic gluconeogenesis. Note that elevated LDL does not contribute to insulin resistance.
What are the 3 derivatives of proopiomelanocortin (POMC)?
ACTH, beta-endorphins (pain response), and alpha-MSH (stimulates melanocyte production of melanin and suppresses appetite).
What affect does PTHrP have on 1,25-hydroxyvitamin D production?
Very little. Unlike PTH, PTHrP does not increase vitamin D production due to slight structural differences, but it does increase serum calcium and decrease serum phosphate.
