Endocrine: 15.5: Parathyroid Flashcards
Decreased serum free Ca++ stimulates _____.
the parathyroid glands –> increased PTH
Why does hypercalcemia cause acute pancreatitis?
Ca++ is an enzyme activator
What is pseudohypoparathyroidism?
- end-organ resistance to PTH (no response)
- defective Gs protein
How does someone get pseudohypoparathyroidism?
it’s auto. dominant
What are the consequences of hypercalcemia?
- nephrolithiasis
- nephrocalcinosis (Ca++ deposited into the tubules)
- CNS disturbances (depression, sz)
- constipation
- acute pancreatitis
- PUD
- osteitis fibrosa cystica
What will the PTH level be in primary hyperparathyroidism? Why?
- increased
- the adenoma is secreting it
What will the serum PTH level be in secondary hyperparathyroidism? Why?
- increased
- from increased secretion of PTH
What will the serum PO4- level be in secondary hyperparathyroidism? Why?
- increased
- increased absorption from the kidneys
What will the serum PO4- level be in primary hyperparathyroidism? Why?
- decreased
- decreased renal absorption
What will the serum alk. phos. level be in secondary hyperparathyroidism? Why?
- increased
- PTH is causing increased osteoblast activity in the bones
What is the key cell in the parathyroid gland?
Chief cells
What is the effect of PTH in the GI tract?
activates vitamin D –> increases absorption of Ca++ and PO4- in the small intestine
What is the most common cause of primary hyperparathyroidism?
parathyroid adenoma
What is parathyroid adenoma?
a benign neoplasm that produces excess PTH –> hypercalcemia
What will the lab findings be in pseudohypoparathyroidism?
- hypocalcemia
- increased PTH
What is the tx for primary hyperparathyroidism?
surgical removal of gland
An alkaline environment is necessary to activate _____ and ______ calcium on bone.
- osteoblasts
- lay down
What is the effect of PTH in the bones?
activates osteoblasts –> increased osteoclast activity –> resorb bone –> release Ca++ and PO4- into the blood
What will the serum Ca++ level be in secondary hyperparathyroidism? Why?
- decreased
- high phosphate decreases serum Ca++
What is osteitis fibrosa cystica?
Loss of Ca++ from bones –> fibrosis, cysts
What physical exam findings are assoc. with pseudohypoparathyroidism?
- short stature
- short 4th and 5th digits
What lab findings are seen in hypoparathyroidism?
- decreased PTH
- decreased serum Ca++
What affect does DiGeorge Syndrome have on the parathyroid gland?
agenesis –> decreased PTH (hypoparathyroidism)
What will the urinary cAMP level be in primary hyperparathyroidism? Why?
- increased PTH
- activates Gs –> adenylate cyclase –> increased cAMP
What does phosphate bind?
free Ca++
Renal failure causes _____ hyperparathyroidism.
secondary
What is the effect of PTH in the kidneys?
- increases calcium reabsorption
- decreases PO4- reabsorption
What is secondary hyperparathyroidism?
extrinsic increased PTH (not from the parathyroid gland itself)
This is the loss of Ca++ from bones –> fibrosis, cysts.
osteitis fibrosa cystica
What will the serum alk. phos. level be in primary hyperparathyroidism? Why?
- increased
- increased osteoblast activity in bone
What is a marker for increased osteoblast activity?
increased serum alk. phos.
What is primary hyperparathyroidism?
excess PTH due to a disorder of the parathyroid gland itself
What is hypoparathyroidism?
low PTH due to a problem with the parathyroid glands
What will the serum Ca++ level be in primary hyperparathyroidism? Why?
- high
- increased GI, bone, and kidney resorption
What are the systemic affects of hypoparathyroidism?
- numbness and tingling (esp. perioral)
- tetany/muscle spasms (esp. on facial nerve tapping, upon BP cuff inflation)
What kind of receptor is PTH coupled to? What are the downstream affects?
Gs –> adenylate cyclase –> cAMP
