w5 - bone disorders inc OP Flashcards
define osteoporosis
progressive systemic skeletal disease
low bone mass, micro-architecture deterioration
incr in bone fragility + fracture susceptibility
how much of the adult keleton is remodelled each year
10%
bone remodelling occurs at discrete foci called bone remodelling units. OUtline
osteoclasts - appear on inactive surface, begin to absorb bone
osteoblasts - replace OC, fill cavity with osteoid, mineralised to form new bone
in OP there is a problem with bone remodelling, what is it
incr in resorption over formation, leading to bone loss
regulating factors for peak bone mass 5
genetics body weight sex hormones diet exercise
regulating factors for bone loss 7
sex hormone deficiency body weight genetics diet immobility diseases drugs (glucocorticoids, aromatase inhibitors)
common fracture sites in OP
neck of femur
vertebral body
distal radius
humeral neck
how is bone density measured
DEXA scans
ranges of normal, osteopenia, oP, sev. OP in BMD
normal: BMD within 1 SD of young adult reference
Osteopenai (low bone m.): BMD: 1-2.5 SD below young a. ref.
OP: BMD >2.5 below young a. ref.
Sev. OP: BMD >2.5 below + fragility fracture
in OP target therapeutic inervention is for those at high risk of …
low impact fracture
SIGN guideline is based on fracture risk and not BMD, and treatment based on addressing risk factures, what are modifiable/non-modifiable risk factors
modifiable BMD alcohol smoking weight inactivity pharmacological factors
non-mod age gender ethnicity pre. fracture FH menopause <45yrs comorbidities
tool used to assess risk of fracture
WHO fracture risk calculator
who to assess? when to refer to DXA
> 50yrs
<50 + early menopause or on glucocorticoids
if risk >10%
investigations for OP
U+Es LFTs Bone biochem FBC PV TSH
protein electrophoresis/bence jones proteins coeliac antibodies testosterone 250H VitD PTH
2ndary causes of OP can be due endo, GI, resp, or others. give examples
endocrine
- hypothyroid
- hypoparathyroid
- cushings
GI
- coeliac
- IBD
- chronic liver disease
- chronic pancreatitis
resp
- CF
- COPD
chronic kidney disease
lifestyle advice for management of OP includes high intensity strength training, avoiding excess alcohol and smoking. name 2 more
low impact weight bearing exercise
fall prevention
diet for op
700mg calcium (2-3portion from dairy) if post menopause - 1000mg calcium (3-4portions)
non-dairy sources of caclium
bread and cereals
fish with bones
nuts
green veg
drug treatments for OP
calcium + Vit D supplemwents biphosphonates denosumab teriparatide HRT SERMS Testosterone
vit D deficiency at risk patients
low exposure to suun
house-boound
calcium supplements should not be taken within 2 hours of oral __
biphosphonates
t.f if dietary calcium is adequate, 700mg Vit D is preferred
true
biphosphonates are ___ agents, examples are alendronate and risedronate. They work by preventing bone loss at all sites vulnerable to OP.
They are 1) anologues of ____, that absorb onto bone within matin the matrix
2) ingested by ___, leading to cell death
biphosphonates are anti-resorptive agents, examples are alendronate and risedronate. They work by preventing bone loss at all sites vulnerable to OP
They are 1) anologues of pyrophosphates, that absorb onto bone within matin the matrix
2) ingested by osteoclasts, leading to cell death
duration of biphosphonate therapy
5yrs
10yrs if vertebral fracture
zoledronic acid is given through
1 yearly IV infusion for 3yrs
1 in 3 patients suffer an acute phase reaction with the first infusion of zoledronic acid, what is given
paracetamol
denosumab is a monoconal antibody that targets ___. preventing activation of its receptor, inhibiting development and activity of ____, decreasing bone ___
denosumab is a monoconal antibody that targets RANKL. preventing activation of its receptor, inhibiting development and activity of Osteoclasts, decreasing bone resorption
how is denosumab administered?
adverse effects of denosumab?
contraindicated in renal impairment t.f?
6mnthly SC injection
adverse: hypocalcaemia, eczema, cellulitis
false
teriparatide is a recombinant ___ hormone, it stimulates bone growth (anabolic). when is it considered?
parathyroid
> 65yrs T
when to treat OP with antiresorptive therapy
T < -2.5
if ongoing steroid requiremnt >7.5mg prednisolone for 3mnths, or vertebral fracture, consider treatment with T
what are 3 direct iimpacts and 1 non-direct impact of glucocorticoids and bone
direct
- reduces Osteoblast activity + lifespan
- suppresses replication of OB precursors
- reduces calcium absorption
indirect
inhibits gonadal + adrenal steroid productio n
glucocorticoids effect on calcium metabolism
incr excretion and reduces absorption in gut
reduces matrix synthesis resorption
impact of pit and kidneys too
pagets disease is abnormal ___ activity, followed by incr __ activity. leading to abnormal bone structure with reduced strength and incr fracture risk. name for single site and multiple sites
pagets disease is abnormal osteoclastic activity, followed by incr osteoblastic activity. leading to abnormal bone structure with reduced strength and incr fracture risk.
monostotic =single
polyostotic = multiple
bones usually affected by pagets
long bones
pelvis
lumbar spine
skull
pagets presentation
bone pain
deformity
deafness
compression neuropathies
pagets is diagnosed on __, isotope bone scan used to show ___, biochem shows raised ___ ___ with otherwsie normal __ . Treated with ___ if pain not responding to analgesia
pagets is diagnosed on XR,
isotope bone scan used to show distribution, biochem shows raised alkaline phosphatase with otherwsie normal LFTs. Treated with biphosphonates if pain not responding to analgesia
osteogenesis is inherited through __ __ pattern, most are secondary mutations of __ ___ __ genes (COL1A1, COL1A2)
autosomal dominant
type 1 collagen
associations of osteogenesis imperfecta 2
dentinogenesis imperfects
blue sclerae
more sev. form of osteogeneis imperfecta presents with __ in __. No cure, only fracture fixing/surgery for deformities/biphosphonates.
fractures
childhood
