Firecracker Endo I Flashcards
Which hormones use a guanylate cyclase-cGMP mechanism?
ANP, NO (EDRF)
Amyloid stroma with sheets of cells are found in what type of thyroid cancer?
Medullary
Parafollicular cells synthesize and secrete
calcitonin
Medullary thyroid cancer originates from
parafollicular (C cells)
Thyroglobulin is a marker for what type of thyroid cancer?
well differentiated papillary
Which hormones use an adenylate cyclase – cAMP signaling mechanism?
FLAT CHAMP
FSH, LH, ACTH, TSH
CRH, hCG, ADH (V2), MSH, PTH
also: calcitonin, GHRH, glucagon
What is the primary source of ghrelin secretion?
P/D1 cells in fundus of stomach
Thyroglobulin is stored in which part of thyroid gland?
Colloid
Ghrelin effects
1) ↑ GH, cortisol, ACTH & prolactin secretion
2) Food seeking via the vagus nerve of the PNS & the arcuate nucleus of the hypothalamus
What kind of signaling molecules use receptor tyrosine kinases?
Growth factors (insulin, IGF-1, FGF, PDGF, etc.) often signal through receptor tyrosine kinases .
Where in the cell does a prohormone become a hormone?
Golgi apparatus
What are Orphan Annie eye nuclear inclusions?
empty-appearing nuclei w/ uniform staining
What are Psammoma bodies?
round concentric collection of calcium
Which hormones use an IP3-Ca2+ mechanism?
GOAT
GnRH, Oxytocin, ADH (V1 receptor), and TRH
Which endocrine hormones use the JAK/STAT pathway as an intracellular signaling mechanism?
PIG
Prolactin, IL-2 and GH use this mechanism
Where is the thyroid hormone receptor found when it is not bound to hormone?
Nuclear: T3/T4
Leptin is released by what cells?
Adipose
What do leptin levels correlate with?
overall body fat mass
Which steroid hormones have cytosolic receptors?
VET CAP
Vitamin D, Estrogen, Testosterone, Cortisol, Aldosterone, Progesterone
What is different about ghrelin levels in Prader-Willi patients?
do not decrease after a meal → continuous food-seeking, weight gain
What modification converts a preprohormone to a prohormone?
cleavage of a signal peptide from the preprohormone
Where does preprohormone synthesis take place?
ER
How does PTH (parathyroid hormone) affect the renal handling of phosphate?
PTH (parathyroid hormone) induces NPT2 endocytosis → ↓ reabsorption of phosphate and ↓ reabsorption of HCO3-
Women and people with a history of neck radiation are at highest risk for what type of thyroid cancer?
Papillary
What are the 3 effects of leptin on energy and fat homeostasis?
1) ↓ Food intake
2) ↑ Metabolic rate, activity level, and temperature
3) Inhibition of insulin synthesis and release
What is the effect of PTH (parathyroid hormone) on renal Ca2+ absorption?
↑ Renal Ca2+ absorption in DCt
When hypothyroidism is clinically suspected, what is usually the most sensitive test?
serum TSH
Can you describe the pathogenesis of exophthalmos (proptosis) in patients with Graves disease?
TSI & other ABs cross-react w/ & stimulate orbital preadipocyte fibroblasts (wh/ express TSH Rs) to synthesize hydrophilic glycosaminoglycans
Primary hyperthyroidism labs
Decreased TSH
Increased T4/&3
How does PTH affect urinary phosphate excretion?
↓ Kidney reabsorption of phosphate → ↑ phosphate excretion (phosphaturic effect).
Mnemonic: PTH = Phosphate Trashing Hormone
What is thyrotoxicosis?
clinical syndrome characterized by high levels of circulating thyroid hormone –> hyper metabolic state with SNS overactivity
What drugs inhibit thyroid peroxidase?
Thyroid peroxidase is inhibited by propylthiouracil and methimazole
How does thyroid carcinoma commonly present?
Painless enlargement of the thyroid gland.
More advanced lesions: hoarseness (from recurrent laryngeal nerve involvement), dysphagia and cough.
Diagnostic tests for thyroid carcinomas
ultrasound, FNA (fine needle aspiration) and radionucleotide scans (scintigrams).
thyroid carcinoma on scintigram
cold nodules
What is the most common cause of hypothyroidism worldwide?
Endemic dietary iodine deficiency
Children with mental retardation, pot-bellied stomach, protruding umbilicus and protuberant tongue. Faces are pale and puffy.
Cretinism
Testing of all newborns for hypothyroidism (elevated TSH) is standard of care because mental retardation can be minimized when
thyroid hormone is administered in neonatal period.
What urinary metabolite reflects PTH action at the proximal tubule?
↑ urinary cAMP.
What is thyroid ophthalmopathy?
↑ SNS → overstimulation of levator palpebrae superioris (a muscle which receives SNS innervation from the internal carotid plexus & contracts reflexively to elevate the upper eyelid) → wide-eyed staring gaze and lid lag
For patients with primary hypothyroidism, are the following lab values ↑, ↓, or within normal limits?
- serum TSH
- total T4
- free T4
- T3 resin uptake
up, down, down, down
Can you name 3 immunologic mechanisms which may cause thyroid cell death in patients with Hashimoto thyroiditis?
1) CD8+ T-cell mediated cell death
2) Cytokines activate TH1 → IFN-γ recruits and activates macrophages → follicle damage
3) Anti-thyroid autoantibodies (anti-Tg and anti-TPO) → ADCC (antibody-dependent cell-mediated cytotoxicity)
What are the anti-thryoid antibodies?
- Anti-Tg (thyroglobulin) antibodies
- Anti-TPO (thyroid peroxidase) antibodies
With what genes is Hashimoto’s associated?
Associated with HLA-DR3 and HLA-DR5
Congenital hypothyroidism is most commonly caused by thyroid dysgenesis due to
thyroid aplasia/hypoplasia/ectopy
8 presenting signs of congenital hypothyoidism
- hoarse cry
- umbilical hernia
- jaundice
- hypotonia
- macroglossia (protruding tongue)
- enlarged fontanelles
- coarse facial features, dry skin with scarce lanugo, pale body with mottled cool extremities
- constipation & somnolence
What metabolite detected in the urine reflects PTH-mediated bone resorption?
↑ Hydroxyproline excretion
What is the net effect of PTH (parathyroid hormone) on serum [Ca2+] and serum [phosphate]?
Increases calcium and decreases phosphate
What is the treatment of secondary hyperparathyroidism?
Calcitriol (vitamin D) and phosphate binders such as aluminum hydroxide or calcium carbonate
What is the mechanism of action of high dose iodine supplementation in treatment of hyperthyroidism?
blocks release of T4 and T3 into the circulation
