Metabolic Bone Diseases

Question 1

_____ bone surrounds ______ bone

Answer 1

cortical; trabecular

Question 2

_____ and _____ are potent activators of osteoclast activity

Answer 2

PTH; 1,25(OH)2D

Question 3

diagnosis of osteoporosis

Answer 3

DEXA T-score <-2.5

Question 4

pathogenesis of osteomalacia

Answer 4

defective mineralization/calcification of osteoid

Question 5

osteomalacia: ____ serum calcium, ____ PTH secretion, ____ serum phosphorus, ____ ALP

Answer 5

low serum calcium, high PTH secretion, low serum phosphorus, high ALP

Question 6

CaCO3 is ___% elemental calcium, while Ca citrate is ___% elemental calcium

Answer 6

40; 21

Question 7

treatments for osteoporosis (4) and their mechanism

Answer 7

1. SERMs (tamoxifen, raloxifene): prevent increased remodeling
2. bisphosphonates (alendronate, risedronate, pamidronate, zoledronic acid): stimulates osteoclast apoptosis via inhibition of protein farnesylation
3. denosumab: decoy receptor for RANKL, interrupts RANKL-RANK signaling and prevents osteoclast differentiation
4. teriparitide: anabolic, fragment of PTH

Question 8

tumor-induced osteomalacia (TIO): pathogenesis

Answer 8

benign tumor that secretes large amounts of FGF23 –> hypophosphatemia –> osteomalacia

Question 9

rickets: pathogenesis

Answer 9

abnormal bone modeling when osteomalacia is present prior to the closure of the epiphyses –> bowing of bones

Question 10

dx: woven bone, foci of exuberant, unregulated bone turnover

Answer 10

Paget disease of bone

Question 11

dx: increased hat size, deafness

Answer 11

Paget disease of bone

Question 12

Paget disease of bone: unique lab findings

Answer 12

normal serum calcium, phosphorus, and PTH, but increased ALP

Question 13

Paget disease: increased risk of what?

Answer 13

osteosarcoma

Question 14

which bisphosphanates are oral and which are IV?

Answer 14

oral: alendronate, risedronate
IV: pamidronate, zoledronic acid