Bone Disorders (osteoporosis, etc) Flashcards Preview

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Flashcards in Bone Disorders (osteoporosis, etc) Deck (36)
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osteoporosis is due to loss of what kind of bone

loss of trabecular (spongy) bone and inteconnections


MC type of fracture in osteoporosis

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


Type II osteoporosis

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


causes of type II osteoporosis (2)

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


what causes type I, or postmenopausal osteoporosis (mechanism)

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


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

1. femoral neck fx
2. Colles' fx--> fx of distal radius

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


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

all normal


treatment of osteoporosis

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)


drug that is an analogue of PTH

teriperatide--> cant use for more than 3 years


how do bisphosphonates work

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


denosunab MOA (used for extreme osteoporosis)

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


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

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


2 AEs of bisphosphonate use

1. erosive esophagitis (wash down with lots of water)
2. osteonecrosis of the jaw


disease with thickened, dense bones that are prone to fx

osteopetrosis (marble bone disease)


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

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


what x-ray finding is seen in osteopetrosis

"bone in bone" appearance--> bones will flare at the end

* erlenmeyer flask deformity--> distal metaphysis of radius and ulna are flared


what two complications can be seen with osteopetrosis

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!!)


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

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


bone pain, enlargement of bone, headaches, hearing loss

Paget's disease of bone (osteitis deformans)


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

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


what three bones affected in Paget's

pelvis, skull, femur


characteristic bone pattern in Paget;s

mosaic "woven" bone-->


what goes wrong in Paget's

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


serum Ca, Phos, Alk phos, PTH in Pagets

↑ Alk phos only--> highly characterisitic!!


3 complications of Paget's

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


osteomalacia/ rickets causes

Vitamin D deficiency


what does vitamin D deficiency do to cause trouble

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


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

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


disease caused by hyperparathyroidism

Osteitis fibrosa cystica (von Recklinghausen disease of bone)


how does increased PTH lead to trouble in bone

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

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