Parathyroid Glands Flashcards
What is the cell type of interest in the parathyroid glands and what do they do? what are the target tissues?
Chief cells
secrete parathyroid hormone (PTH) in a simple feedback system in response to low blood Ca
target tissues are bone and kidney
what disorder do we have to know involving hypo function of the parathyroid gland?
hypoparathyroidism
what disorder do we have to know involving hyperfunction of the parathyroid gland?
hyperparathyroidism
- primary (functional parathyroid tumors)
- secondary (renal and nutritional)
- pseudohyperparathyroidism (hypercalcemia of malignancy)
what pathophy thing does hypoparathyroidism result in?
subnormal amounts of PTH
is hypoparathyroidism common?
nope, it’s infrequent
what are some potential causes of hypoparathyroidism?
lymphocytes parathyroiditis
destruction by a primary or metastatic tumor
parathyroid gland atrophy
accidental surgical removal
what clin path thing does hypoparathyroidism result in? how does this manifest clinically?
hypocalcemia
restless, ataxic, weak, tremors, tetany, seizure (neuro presentation basically)
primary hyperparathyroidism is a result of… what?
functional chief cell neoplasm
primary hyperparathyroidism occurs most commonly in what signalment/species?
older dogs
what pathophys thing does hyperparathyroidism result in?
excess secretion of PTH
what are the consequences of excess PTH?
- bone lesions from widespread osteoclastic resorption (fibrous osteodystrophy)
- hypercalcemia
how does hypercalcemia manifest clinically?
anorexia, vomiting, diarrhea, depression, PU/PD, muscle weakness, ST mineralization
what are the two causes of secondary hyperparathyroidism in broad stokes?
renal & nutritional
what are the two renal mechanisms of secondary hyperparathyroidism that we have to know?
excess PTH due to hypocalcemia, which is secondary to hyperphosphatemia
impaired production of active form of Vitamin D
what are the 3 nutritional mechanisms of secondary hyperparathyroidism that we have to know? which one is most common?
low calcium
inadequate Vit D
high P –> most common
high P in horses causing nutritional secondary hyperparathyroidism is called what colloquially?
Bran Disease or Big Head
You get parathyroid glands from a horse that look like this. You’ve ruled out a chief cell tumor. what is going on?
secondary hyperparathyroidism from either renal or nutritional mechanisms. given that this is a horse, I’m guessing nutritional (high P)
Pseudohyperparathyroidism is also called… ?
Humeral hypercalcemia of malignancy
what is the most common cause of hypercalcemia?
hypercalcemia of malignancy
what are the two most common malignancies that cause hypercalcemia of malignancy?
lymphosarcoma and apocrine gland carcinoma of the anal sac
what is humeral hypercalcemia of malignancy caused by?
over-production of PTH-related protein (PTHrP) by neoplastic cells
which is more common in a functional chief cell neoplasm, carcinomas or adenomas?
adenomas > > carcinomas
