osteoporosis osteomalacia pagets

Question 1

synthesized by osetoblasts, key regulator of phosphate homeostasis

Answer 1

FGF23

Question 2

osteoclasts secrete ___ to disolve ____ and ____ to degrade bone matrix proteins

Answer 2

secrete HCl to dissolve mineral and cathepsin K to degrade bone matrix proteins

Question 2

oral bisphosphponates

side effects + contraindications

Answer 2

aalendronate

risedronate

esophogeal irritation

contraindicated for pt with GFR

Question 3

osteomalacia =

Answer 3

undermineralized bone matrix leads to weakened bone architecture

Question 4

Antiabsorptives

Answer 4

Denosumab

Calcitonin

Question 4

side effects calcitonin

Answer 4

tachyphylaxis - rapid loss of response to drug

nausea

Question 4

Anabolic + mechanism

Answer 4

Teriparatide - fragement of parathyroid hormone, PTH stimulates bone remodeling

(continuous admin leads to bone loss)

Question 5

in adution to promoting phophaturia, FGF23inhibits expression of ____ thereby ___-

it also increases activity of 24-hydroxlyase, increasing ___

Answer 5

inhibits expression of 1-hydroxylase, thereby reducing vitamin D activation

activity of 24-hyrdroxylase increasing vitamin D clearance

Question 5

pathophys Autosomal dominant hypophopphatemic rickets

X-linked and Autsomal recessive

Answer 5

AD = mitations in argiinate residues preventing normal proteolytic degradation of FGF23

X-linked - PhEX gene mutations prevent normal proteolytic degradation

AR = DMP1 mutations prevent degredation

Question 7

interfaces between osteons

Answer 7

cement lines

Question 7

selective estrogen receptor modulators for low BMD

mechanism

Answer 7

tamoxifen

raloxifene

prevent increased remodeling

Question 8

PTH levels in osteomalacia

underlying mechanism

Answer 8

elevated, mineral diciency drives secondary hyperparathyroidism

Question 9

pathophys Paget’s disease

presentation

Answer 9

unregulated bone turnover > woven, increased intravascularity

headache

deafness (impingent)

limb bowing

increased risk of osteosarcoma

Question 10

IV bisphosphonates

side effects and contrandications

Answer 10

pamidronate

zoledronic acid

hypocalcemia,

acute phase rxn (flu-like symptoms)

contrainidicated for pt with GFR

Question 11

tamoxifen side effects

alternate indications

Answer 11

increased thromboembolic risk

breast cancer adjunct

Question 12

tumor induced osteomalacia pathophys and presentation

Answer 12

benign tumor of mesenchymal origin secreting large amounts of FGF23

serum phos falls and patients develop fatigue and proximal weakness

osteomalaic with detectable bone lonss on DXA

Question 14

in osteomalacia, osteoid surface volume is

Answer 14

increased

Question 16

relative bone volume, cortical vs trabecular

Answer 16

80-90% cortical bone

Question 17

inhibit converion of mevalonate to farnesyl, interfering with protein moification in osteoclasts, leading to apoptosis

Answer 17

Bisphosphonates

alendronate,

risedronate

panidronate

zoledrinc acid

Question 18

osteopororsis =

Answer 18

compromised bone strength due to bone densitiy and bone quaility that leads to increased risk of fracture

Question 19

pathophys of vitamin D resistant rickets

Answer 19

mutations of 1-hyroxylase encoded by CYP27B1 and

Vitamin D receptor encoded by VDR

Question 20

signs of proper osteoblast activity in osteomalacia

Answer 20

elevated P1NP

elevated Alk Phos

Question 21

people do not suffer from low bone mineral density unless

Answer 21

fractures

Question 22

Chronic negative Ca blance leads to _____ and if significantly prolonged, _____

Answer 22

secondary parathyroidism, if sufficiently prolonged, osteomalacia

Question 24

accounts for 80% of bone turnover

Answer 24

trabecular

Question 25

Denosumab mechanism

side effects

Answer 25

decoy of receptor for RANK-L > prevents osteoclast differentiation

ONJm atypical femoral fractures

increase risk of skin infection

nauea, weakness, fatigue

Question 26

___ and ___ are potent activators of osteoclast activity, providing free Ca and PO4

Answer 26

PTH

1,25diOHD

Question 28

pseudofracture of femur common in ricketts

Answer 28

looser zone fracture

Question 29

compressive strength comes from

tensile from

Answer 29

compressive from mineral

tensile strength from protein (predominantly type 1 collagen)