26: Parathyroid

Question 1

Three major cell types of parathyroid

Answer 1

Chief cells, oxyphil cells, adipocytes

Question 2

Chief cells on histology

Answer 2

Central round nuclei, light pink/white cytoplasm, secretory granules

Question 3

Oxyphil cells on histo

Answer 3

Smaller darker nuclei, eosinophilic granules

Question 4

Two effects of PTH on kidney

Answer 4

Ca resorption, converts 25(OH)D to 1,25(OH)2D

Question 5

CaSR

Answer 5

Ca-sensing receptor on parathyroid: regulates amount of PTH secreted

Question 6

What leads to Rugger jersey sign on spinal XR

Answer 6

Renal osteodystrophy -> dissecting osteitis

Question 7

Biggest way to tell difference between primary and tertiary hyperparathyroidism

Answer 7

Tertiary always comes after a prolonged period of secondary hyperparathyroid

Question 8

Major EKG change due to hypercalcemia

Answer 8

Shortened QT interval

Question 9

DEXA: where to scan central vs screening exam

Answer 9

central: lower spine and hip
screening: writs, heel, leg, fingers (can also be used if pt isn’t mobile enough to get onto hard xray table)

Question 10

Risks for developing osteoporosis

Answer 10

estrogen depletion, age 70+, anorexia, malapsorption, obesity, steroids, hypogonadism, immobility

Question 11

three things that cause high PTH, high Ca

Answer 11

1. parathyroid adenoma
2. primary hyperparathyroidism
3. parathyroid carcinoma

Question 12

two thing that cause low PTH, high Ca

Answer 12

1. humoral hypercalcemia of malignancy

2. local osteolytic hypercalcemia

Question 13

two things that cause low PTH, low Ca

Answer 13

1. Di George

2. CaSR activation mutation

Question 14

two things that cause high PTH, low Ca

Answer 14

1. kidney disease causes secondary parathyroid hyperplasia

2. calciphylaxis

Question 15

____ is usually asx, but when it does present, it presents with stones, bones, moans, and groans

Answer 15

primary hyperparathyroidism

Question 16

what causes osteitis fibrosis cystica

Answer 16

primary hyperparathyroidism

Question 17

sx of high Ca, low PTH

Answer 17

AMS, N/V, shortened QT interval

Question 18

how does humoral hypercalcemia of malignancy work?

Answer 18

tumor produces PTHvP

Question 19

local osteolytic hypercalcemia

Answer 19

breast CA or myeloma -> metz to bone -> osteoclast bone resoprtion -> releases Ca

Question 20

sx of low Ca

Answer 20

numbness and tingling, stupor, muscle cramps/spasms, tetany, Trousseau and Chovstek signs

Question 21

how does kidney disease cause low Ca

Answer 21

less PO is excreted -> binds Ca in the blood

Question 22

labs in pseudohypoparathyroidism

Answer 22

nl/high PTH, low Ca, high PO

Question 23

mutation in Albright’s hereditary Osteodystrophy

Answer 23

GNAS