Metabolic Bone Diseases - waldron Flashcards
What resorbs bone
osteoclasts
what forms new bones
osteoblasts
what does the imbalance between new bone formation and resorption lead to
bone disease
what is any bone disorder resulting from chemical aberrations
metabolic bone disease
what are building blocks for bone formation
calcium
phosphorus
IGF
osteoblasts and osteoclasts
what is a low bone density
osteopenia and osteoporosis
what increases risk of developing osteopenia and osteoporosis
age
+FH
small framed caucasian and asian women (highest risk)
what is primary osteoporosis
type 1: postmenopausal most prevalent form
type 2: senile (age related, men and women >70)
what is secondary osteoporosis
bone loss associated with other conditions
-malignancies, long-term corticosteroid use, GI disorders, hormonal imbalances
what hormone disorders can expedite bone loss
Cushings
thyroid disorders
hyperparathyroidism
DM
What medications can expedite bone loss
Corticosteroids*
SSRIs
PPIs
Aromatase inhibitors
DM medications (SGLT2, Pioglitazone)
Hepatin
at what age does bone remodeling become ‘unbalanced’
after age 30
what are modifiable risk factors of osteoporosis and osteopenia
ETOH, smoking, low body weight, sedentary lifestyle
Low Ca, low vitamin D, cortiocosteroid use
what are non-modifiable risk factors of osteoporosis and osteopenia
advanced age
caucasian or asian race
female gender (biological)
What are fragility fractures
any fracture that results from low-injury
typically, fall from standing height or less or no identifiable trauma
What is the gold standard screening test for osteoporosis and osteopenia
DEXA (dual-energy x-ray absorptiometry)
T-scores
what are indications for bone density testing?
All women (post menopausal) > 65, Men >70
women <65, men <70 with risk factors or +FH
women who have been on HRT
anyone with fragility fracture
patients with RA
What is measured with DEXA scan
bone density
lumbar spine L1-4, femoral neck and total femur (hip)
What is a normal bone density range
+1 to -1
what is the osteopenia bone density range (below average)
-1 to -2.5
What is osteoporosis bone density range (significantly below average)
-2.5 to -4
How often should DEXA scans be repeated
based on T score
-1 to -1.5: every 5 years
-1.5 to -2.0: every 3-5 years
score under -2.0: every 1-2 years
What tests do you ALWAYS want to check for osteomalacia?
Vitamin D
co-occuring vitamin D deficiency common
all osteopenic and osteoporotic patients should get screened
How do we assess vitamin D levels?
25-hydroxyvitamin D (25(OH)D) is the best measure
circulating (active) form of vitamin D
Normal is 25-80 ng/mL
what levels are indicative of Vitamin D insufficiency
20-25 ng/mL
what levels are indicative of Vitamin D deficiency
<20 ng/mL
What are some other potential test you might want for osteoporosis/osteopenia
CBC
CMP
Phosphorus
Vitamin D
What is the treatment of osteoporosis
PREVENTION (first line)
weight bearing/resistance exercising
fall prevention
vitamin supplementation
Who gets pharmacologic treatment with osteoporosis?
DEXA, FRAZ and hx fragility fractures guide treatment decision
T-score of < -2.5
osteopenia and 10-year hip fracture risk >3%
10 year major fracture risk of >10%
any patient with a fragility fracture
What are the pharmacologic treatment options for osteoporosis?
Vit D + Calcium
Bisphosphonates
Denosumab
Teriperatide
SERMs
Calcitonin
besides calcium and vitamin D, what is the first line pharmacologic agent for osteoporosis?
Bisphosphonates
-alendronate, risendronate, zoledronic acid, ibandronate)
What are the side effects of bisphosphonates
abdominal pain, heart burn, esophageal irritation, ulcers
acute inflammatory response with arthralgia and myalgia
hypocalcemia post-infusion
osteonecrosis of the jaw
atypical subtroachanteric femur fracture
What is Danuzomab
anti-resportive: recombinant antibody med used for osteoporosis
inhibits RANK-ligand to bind to RANK
IV twice a year
What is a decreased mineralization of newly formed osteoid at sites of bone turnover (vit D deficiency or defect in Vit D metablism)
osteomalacia
what does osteomalacia result in
hypocalcemia
hypophosphatemia
direct inhibition of mineralization process
What is a Vitamin D deficiency or defect in Vit D metabolism in CHILDREN
Rickets
affects bones and cartilages
What is the clinical pressentation of osteomalacia
diffuse muscle weakness, especially pelvic girdle
bone pain
waddling gait
fractures following minor (or no) trauma
What is the presentation of Rickets
children develop permanent skeletal deformities
what is the workup for osteomalacia
bone density measurement
bone biopsy
blood work - vit D, calcium, phosphate, PTH
Xray
what are Milkman lines or looser zones diagnostic of
osteomalacia
What is the treatment of osteomalacia
high dose vitamin D (50,000U PO 2x/week for 6-12 months then 1,000-2,000U QD)
phosphate and vit D supplementation in renal phosphate wasting
calcium supplementation
What is Paget’s disease of bone
inflammatory disorder of the bone
accelerated rate of bone remodeling resulting in overgrowth f bone in aging skeleton
M>W; predominantly after age 55
What bones are commonly affecting with Pagets disease
skull, spine, pelvis (most common), long bones, ribs
what is the pathophysiology of Pagets disease
Lytic phase: hypervascularity, osteoclast dysfunction- bond resorption
Mixed phase: osteoclast dysfunction persists, osteoblast activity increases to compensate, rapid formation of dysfunctional, disorganized bone
Sclerotic phase: bones ‘burn out’, disorganized matrix persists, but cell function declines, vascularity is reduced
What is the presentation of pagets disease
often asymptomatic
may be incidental finding on XR
if symptomatic: bone and joint pain, neuro complication involving skull/spine, +/- nephrolithiasis
What tests are indicative of Pagets disease
PTH - usually elevated
alkaline phosphate = high
hypercalciuria is common
How is Pagets disease diagnosed
primarily made via XR and bone scans
‘cotton ball’ appearance of skull
‘picture frame’ appearance in spine
What is the mainstay treatment for Pagets disease of the bone
Bisphosphonates - inhibits osteoclasts
IV- zolendronic acid is the most effective
What is another name for brittle bone disease
osteogenesis imperfecta
What is the most common cause of osteogenesis imperfecta
genetic disorder
what is the presentation of osteogenesis imperfecta
MSK: fragile bones, deformities, ligamentous laxity, short stature, scoliosis
non-MSK: Blue sclera, dysmorphic-trangle fascies, hearing loss, brownish-opalescent teeth(kids), thin skin, hypermetabolism, MVP or AR
How is OI diagnosed
characteristic history and PE
skin biopsy - abnormal collagen
genetic testing (before and after birth)
what is the treatment of OI
best is prevention of fractures: exercise and PT, prophylactic rods to prevent long bone fractures, bracing
genetic counseling
What is Fibrodysplasia ossificans progressiva
very rare disorder
characterized by progressive extra-skeletal ossification of soft tissues resulting in original skeleton being encased in unyielding new bone; leads to disability and ultimately death from cardiorespiratory failure
what are other names for Fibrodysplasia ossificans progressiva
Munchmeyers disease
stoneman’s disease
myositis ossificans progressiva
what is the presentation of Fibrodysplasia ossificans progressiva
malformed big toes that present at birth
most are bedridden by age 20 and have a life expectancy of 40 years
