020315 bone disorders Flashcards
osteomalacia
mineral components of bone matrix are not present in sufficient quantity
key features of osteomalacia
smudge for mineralization front in double tetracycline test
increased osteoid volume (orange)
PTH is usually elevated
alkaline phosphatase and P1NP are usually elevated b/c osteoblasts are working properly
drugs for treating osteoporosis can be categorized into
antiresorptives
anabolics
MOA of bisphosphonates
inhibit conversion of mevalonate to farnesyl, interfering with protein modification in osteoclasts, ultimately leading to apoptosis
MOA of denosumab
decoy receptor for RANKL so that RANKL is unable to bind to its endogenous receptor RANK. interruption of RANKL-RANK signlaing prevents osteoclast differentiation
anabolic agents
teriparatide–fragment of PTH. continuous administration leads to bone loss. but given episodically, exerts an anabolic effect
low BMD can be due to
osteoporosis
osteomalacia
FGF23
phosphaturic hormone
inhibits expression of 1-hydroxylase, reducing vit D activation
by lowering phosphate through urinary loss, FGF23 decreases PTH secretion
inhibits mineralization of bone
Paget’s disease
increased incidence of bone remodeling
weak bones
can get nerve entrapment
bone density measures what
minerals
male/female differencs in bone
male bones tend to grow bigger in diameter than female
vertebrae in males are also bigger
men put some new bone on outside of old bone as they age
in women as they age, the trabeculae are more patchy
property of bisphosphonates
they aren’t well absorbed
paths to osteomalacia
decreased vit D or calcium
decreased phosphate in blood
proximal muscle weakness
could be steroid therapy
or vit D deficiency
PTH has what effect on urine Ca?
it decreases urine Ca
