Parathyroid gland

Question 1

key cells in parathyroid gland

Answer 1

chief cell

regulates the serum free ionized calcium via PTH

Question 2

actions of parathyroid gland

Answer 2

releases PTH when Ca is low:

1. incr. activity of bone osteoclasts: releases Ca and phosphate (though starts by activating blasts, which then activates the osteoclasts)
2. incr. small bowel absorption of Ca and phosphate: activates vit D
3. incr. Ca reabsorption and reducing phosphate reabsorption in the kidney

Question 3

primary hyperparathyroidism

Answer 3

excess PTH due to disorder of parathyroid gland itself: adenoma, sporatic hyperplasia, or carcinoma

Question 4

parathyroid adenoma

Answer 4

benign neoplasm that usually causes asymptomatic hypercalcemia

Question 5

consequences of incr. PTH and hypercalcemia

Answer 5

nephrolitiasis (Ca oxalate stone), nephrocalcinosis (deposit Ca in tubules of the kidney), CNS disturbances like depression and seizures, constipation, peptic ulcer disease, and acute pancreatitis, and osteitis fibrosa cystica (cysts in bone)
BONES, STONES, GROANS (abdominal pain/PUD/constipation). PSYCHIATRIC OVERTONES)

Question 6

lab findings in primary hyperparathyroidism. include ALP levels.

Answer 6

high serum PTH, high serum calcium, decr. serum phosphate. dumping phosphate into the urine.
incr. urinary cAMP (PTH binds the tubular cells of the kidney, coupled to a G-stimulatory protein, activates adenylate cyclase, converts to cAMP), incr. serum alkaline phosphatase (generates an alkaline environment. PTH turns on the osteoblasts, which will then activate the osteoclasts. when the osteoblasts are turned on, though, ALK is high). alkaline environment necessary to lay down bone.

Question 7

tx of primary hyperparathyroidism

Answer 7

surgical removal of the offending gland

Question 8

secondary hyperparathyroidism

Answer 8

excess production of PTH d/t disease process extrinsic to the parathyroid gland
most common cause is chronic renal failure

Question 9

renal insufficiency and secondary hyperparathyroidism

Answer 9

leads to decr. phsophate excretion

incr. serum phosphate binds free calcium
decr. free calcium, stimulates the parathryoid glands: hyperparathyroidism

Question 10

lab findings of secondary hyperparathyroidism

Answer 10

incr. PTH, decr. serum calcium, high serum phosphate, high alkaline phosphatase

Question 11

hypoparathyroidism: causes and definition

Answer 11

low PTH

autoimmune damage, surgical excision, and DiGeorge syndrome

Question 12

presentation of hypoparathyroidism

Answer 12

numbness and tingling around the lips, muscle spasms

decr. PTH and decr. serum calcium

Question 13

pseudohypoparathyroidism

Answer 13

due to end-organ resistance to PTH
hypocalcemia with incr. PTH levels
end organ resistance is d/t defect in Gs protein in many cases
autosomal dominant form associated with short stature and short 4th and 5th digits