Bone Disorders (osteoporosis, etc)

Question 1

osteoporosis is due to loss of what kind of bone

Answer 1

loss of trabecular (spongy) bone and inteconnections

Question 2

MC type of fracture in osteoporosis

Answer 2

vertebral crush fractures–> acute back pain, loss of height, kyphosis (forward bending of the spine)

Question 3

Type II osteoporosis

Answer 3

senile osteoporosis–> seen in men and women over 70 years old

Question 4

causes of type II osteoporosis (2)

Answer 4

1. progressive decline in osteoblast function and increased osteoclast function (more resorption than formation
2. decreased activity

Question 5

what causes type I, or postmenopausal osteoporosis (mechanism)

Answer 5

1. ↓ estrogen leads to increased IL-1, IL-6 and TNF by monocytes and cells in marrow
2. these enhance expression of RANKL (on osteoblasts) and RANK (on osteoclast precursor) ⇒ increased production of osteoclasts

*also ↓ expression of OPG, which is a soluble receptor that binds RANK-L and prevents stimulation of osteoblast precursor

Question 6

what are two other fracture other than vertebral that osteoporosis characterisically causes

Answer 6

1. femoral neck fx
2. Colles’ fx–> fx of distal radius

*these occur after falls from normal height, not harsh trauma

Question 7

Serum Ca, Phos, Alk phos, and PTH in osteoporosis

Answer 7

all normal

Question 8

treatment of osteoporosis

Answer 8

1. Stop smoking, drinkin, using corticosteroids
2. weight-bearing exercise
3. Vitamin D and Ca supplements
4. Bisphosphonates
5. PTH tx (anabolic agent on bone)

Question 9

drug that is an analogue of PTH

Answer 9

teriperatide–> cant use for more than 3 years

Question 10

how do bisphosphonates work

Answer 10

pyrophosphate analogues–> bind hydroxyapetite in bone, inhibiting osteoclast resorption of bone

Question 11

denosunab MOA (used for extreme osteoporosis)

Answer 11

RANK-L inhibitor (like OPG), inhibits osteoclast activity

Question 12

which SERM can be used in osteoporosis to reduce risk of vertebral fracture

Answer 12

raloxifene–> only helpful for vertebral fx, also reduces risk of Breast CA

Question 13

2 AEs of bisphosphonate use

Answer 13

1. erosive esophagitis (wash down with lots of water)

2. osteonecrosis of the jaw

Question 14

disease with thickened, dense bones that are prone to fx

Answer 14

osteopetrosis (marble bone disease)

Question 15

what is the defect in osteopetrosis and what cells does it affect

Answer 15

defective carbonic anhdrase II–> failure of normal bone resorption due to impaired osteoclast function (need it to generate acidic environment for bone resorption)

Question 16

what x-ray finding is seen in osteopetrosis

Answer 16

“bone in bone” appearance–> bones will flare at the end

• erlenmeyer flask deformity–> distal metaphysis of radius and ulna are flared

Question 17

what two complications can be seen with osteopetrosis

Answer 17

1. pancytopenia/ extramedullary hematopoiesis (due to bone marrow being replaced by more bone)
2. cranial nerve impingement/ palsy–> compression by increased bone (vision or hearing loss!!)

Question 18

serum Ca, Phos, Alk phos, and PTH in osteopetrosis?

Answer 18

usually normal; possible mild increases in Ca, Alk phos, or PTH, but serum Ca is usually NORMAL

Question 19

bone pain, enlargement of bone, headaches, hearing loss

Answer 19

Paget’s disease of bone (osteitis deformans)

Question 20

what kind of pt would be most likely to present with Paget’s

Answer 20

man over 50 with pain and poorly fitting hats, maybe trouble hearing; esp white dudes

Question 21

what three bones affected in Paget’s

Answer 21

pelvis, skull, femur

Question 22

characteristic bone pattern in Paget;s

Answer 22

mosaic “woven” bone–>

Question 23

what goes wrong in Paget’s

Answer 23

LOCALIZED disorder of bone remodeling caused by increase in both osteoblast and osteoclast activity

Question 24

serum Ca, Phos, Alk phos, PTH in Pagets

Answer 24

↑ Alk phos only–> highly characterisitic!!

Question 25

3 complications of Paget’s

Answer 25

1. pathologic fractures
2. risk of osteogenic sarcoma
3. risk of high-output heart failure (due to arteriovascular connections in bone)

Question 26

osteomalacia/ rickets causes

Answer 26

Vitamin D deficiency

Question 27

what does vitamin D deficiency do to cause trouble

Answer 27

leads to impaired minerlaization/ calcification of osteoid–> soft bones

Question 28

What are serum Ca, Phos, Alk phos and PTH in vitamin D deficiency

Answer 28

1. ↓ serum Ca (leads to–>)
2. ↑ serum PTH (leads to–>)
3. ↓ serum Phos
4. ↑ Alk phos (due to increased osteoblast activity)

Question 29

disease caused by hyperparathyroidism

Answer 29

Osteitis fibrosa cystica (von Recklinghausen disease of bone)

Question 30

how does increased PTH lead to trouble in bone

Answer 30

increased PTH–> increased osteoclast activity (have PTH receptors), particulary when PTH levels are very high

Question 31

characteristic lesions in osteitis fibrosa cystica

Answer 31

“Brown tumors”–> are cystic spaces in bone that are lined by osteoclasts filled with fibrous stroma and blood

*remember cysts= lined by epithelial tissue

Question 32

labs in osteitis fibrosa cystica

Answer 32

1. ↑ serum Ca
2. ↓ serum PTH
3. ↑ Alk phos (indicates bone turnover)
4. ↑↑ PTH

Question 33

Type 1 psuedohypoparathyroidism__. other name

Answer 33

Albright hereditary osteodystrophy

Question 34

what is the issue in Apbright heridiatry osteodystrophy

Answer 34

PTH resisitance at the renal tubules–> dump calcium and keep phosphate (since cant respond to PTH) = get low serum calcium, high phosphate, but with a high PTH level

*can look a lot like osteitis fibrosa cystica; labs are the same

Question 35

Serum Ca, Phos, Alk phos, and PTH in renal insufficiency

Answer 35

1. ↓ Ca
2. ↑ Serum Phos
3. normal or increased Alk phos
4. ↑ PTH

• decreased calcium because no vitamin D is being made in the kidney, also cant excrete phosp, due to poor renal function

Question 36

serum Ca, Phosp, Alk phos, and PTH in vitamin D toxicity

Answer 36

1. ↑ Ca
2. ↑ Phos
3. normal Alk phos
4. ↓ PTH

*Vit D causes lots of calcium, since it causes Ca to be resorbed in kidney and intestines and also causes release from bone (resorption). High Ca causes PTH to decrease, which causes phos to be high (PTH is phos dumping hormone)