definition: osteoporosis
bone deterioration with:
- reduced bone mass
- disruption of micro architecture of bone
what is the T score cut off for osteoporosis?
-2.5 (-2.5 or less means osteoporosis diagnosis)
what type of fracture has the highest mortality?
hip fracture
what is the most common reason for nursing home admittance?
hip fractures
what is the gold standard screening for diagnosing and monitoring osteoporosis?
DXA
what is a Z score?
age matched control
low bone density (osteopenia) is a T score in what range?
- 1.0 down to -2.5
what is a normal T score?
-1.0 to 1.0
anyone with a fragility fracture by definition has:
osteoporosis
when should a T score be used?
- comparing BMD to a person of same age
- younger than peak bone mass
- pre-menopausal women
- men under 50 yo
- evaluating for secondary causes of osteoporosis
recommend BMD testing in women over ____ and men over ____
- women: 65
- men: 75
in postmenopausal women and men 50-70, recommend BMD testing when there is concern based on ______________________
risk factor profile
the WHO FRAX algorithm was developed to calculate:
- 10 yr probability of a hip fracture
- 10 yr probability of any major osteoporotic fracture (defined as hip, forearm, humerus)
consider initiating treatment in postmenopausal women and men over 50 with T score of ______ AND _________
- 1 to -2.5
- 10 yr hip fracture probability 3% or more
how often is BMD testing recommended?
every 2 years
what are limitations of FRAX?
- patients naive to treatment
- only uses T score from hip and does not accomodate peripheral sites or spine T score
what are the anticatabolic drug therapies for osteoporosis?
- bisphosphonates
- SERM
- denosumab
what is the anabolic drug therapy for osteoporosis?
teriparitide
what is the MOA of bisphosphonates?
- bind to bone mineral
- concentrate at sites of bone resorption
- release and intracellular uptake during resorption
- loss of resorptive function
bisphosphonate action depend on what two factors?
- mineral binding
- effects of osteoclasts
what is the MOA of denosumab?
- binds RANK-L and inhibits osteoclast-mediated bone destruction
- osteoclast formation, function, and survival inhibited
- bone resorption inhibited
what factors determine PTH effects on bone?
- administration
- dose
high dose (continuous) PTH has what effect on bone?
catabolic
low dose (daily) PTH has what effect on bone?
anabolic
paget disease of bone is characterized by abnormalities of the ______________ (cell type) and there is _______________ (accelerated / decreased) bone turnover and abnormal bone remodeling
- osteoclast
- accelerated
what is the inheritance of PDB?
AD
what are the labs in PDB?
- increased alk phos (bone specific AP)
- bone turnover markers increased
- calcium and phosphate typically NORMAL
what test should be done in patients with PDB?
baseline bone scan
what do you monitor in PDB?
alk phos
what is the medication of choice for PDB?
- bisphosphonates (zoledronic acid)
definition: rickets
deficient mineralization at the growth plate, as well as architectural disruption of this structure
definition: osteomalacia
impaired mineralization of the bone matrix
rickets and osteomalacia occur together as long as:
growth plates are open (only osteomalacia occurs once the growth plates close)
calcipenic rickets is usually caused by:
dietary deficiency of vitamin D and/or calcium (most common form)
phosphopenic rickets in children and adolescents is almost always caused by:
- renal phosphate wasting (usually isolated)
- generalized tubular disorder (e.g. Fanconi)
- inadequate dietary phosphate / intestinal malabsorption (rare)
- delayed closure of fontanelles
- parietal and frontal bossing
- enlargment of costochondral junction
- widening of wrist
- lateral bowing of femur and tibia
rickets
- elevated alk phos
- reduced serum calcium and phosphorus
- low urinary calcium
- low 25-OH vitamin D
- elevated PTH
osteomalacia